1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * kernel/lockdep.c |
4 | * |
5 | * Runtime locking correctness validator |
6 | * |
7 | * Started by Ingo Molnar: |
8 | * |
9 | * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> |
10 | * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra |
11 | * |
12 | * this code maps all the lock dependencies as they occur in a live kernel |
13 | * and will warn about the following classes of locking bugs: |
14 | * |
15 | * - lock inversion scenarios |
16 | * - circular lock dependencies |
17 | * - hardirq/softirq safe/unsafe locking bugs |
18 | * |
19 | * Bugs are reported even if the current locking scenario does not cause |
20 | * any deadlock at this point. |
21 | * |
22 | * I.e. if anytime in the past two locks were taken in a different order, |
23 | * even if it happened for another task, even if those were different |
24 | * locks (but of the same class as this lock), this code will detect it. |
25 | * |
26 | * Thanks to Arjan van de Ven for coming up with the initial idea of |
27 | * mapping lock dependencies runtime. |
28 | */ |
29 | #define DISABLE_BRANCH_PROFILING |
30 | #include <linux/mutex.h> |
31 | #include <linux/sched.h> |
32 | #include <linux/sched/clock.h> |
33 | #include <linux/sched/task.h> |
34 | #include <linux/sched/mm.h> |
35 | #include <linux/delay.h> |
36 | #include <linux/module.h> |
37 | #include <linux/proc_fs.h> |
38 | #include <linux/seq_file.h> |
39 | #include <linux/spinlock.h> |
40 | #include <linux/kallsyms.h> |
41 | #include <linux/interrupt.h> |
42 | #include <linux/stacktrace.h> |
43 | #include <linux/debug_locks.h> |
44 | #include <linux/irqflags.h> |
45 | #include <linux/utsname.h> |
46 | #include <linux/hash.h> |
47 | #include <linux/ftrace.h> |
48 | #include <linux/stringify.h> |
49 | #include <linux/bitmap.h> |
50 | #include <linux/bitops.h> |
51 | #include <linux/gfp.h> |
52 | #include <linux/random.h> |
53 | #include <linux/jhash.h> |
54 | #include <linux/nmi.h> |
55 | #include <linux/rcupdate.h> |
56 | #include <linux/kprobes.h> |
57 | #include <linux/lockdep.h> |
58 | #include <linux/context_tracking.h> |
59 | |
60 | #include <asm/sections.h> |
61 | |
62 | #include "lockdep_internals.h" |
63 | |
64 | #include <trace/events/lock.h> |
65 | |
66 | #ifdef CONFIG_PROVE_LOCKING |
67 | static int prove_locking = 1; |
68 | module_param(prove_locking, int, 0644); |
69 | #else |
70 | #define prove_locking 0 |
71 | #endif |
72 | |
73 | #ifdef CONFIG_LOCK_STAT |
74 | static int lock_stat = 1; |
75 | module_param(lock_stat, int, 0644); |
76 | #else |
77 | #define lock_stat 0 |
78 | #endif |
79 | |
80 | #ifdef CONFIG_SYSCTL |
81 | static struct ctl_table kern_lockdep_table[] = { |
82 | #ifdef CONFIG_PROVE_LOCKING |
83 | { |
84 | .procname = "prove_locking" , |
85 | .data = &prove_locking, |
86 | .maxlen = sizeof(int), |
87 | .mode = 0644, |
88 | .proc_handler = proc_dointvec, |
89 | }, |
90 | #endif /* CONFIG_PROVE_LOCKING */ |
91 | #ifdef CONFIG_LOCK_STAT |
92 | { |
93 | .procname = "lock_stat" , |
94 | .data = &lock_stat, |
95 | .maxlen = sizeof(int), |
96 | .mode = 0644, |
97 | .proc_handler = proc_dointvec, |
98 | }, |
99 | #endif /* CONFIG_LOCK_STAT */ |
100 | { } |
101 | }; |
102 | |
103 | static __init int kernel_lockdep_sysctls_init(void) |
104 | { |
105 | register_sysctl_init("kernel" , kern_lockdep_table); |
106 | return 0; |
107 | } |
108 | late_initcall(kernel_lockdep_sysctls_init); |
109 | #endif /* CONFIG_SYSCTL */ |
110 | |
111 | DEFINE_PER_CPU(unsigned int, lockdep_recursion); |
112 | EXPORT_PER_CPU_SYMBOL_GPL(lockdep_recursion); |
113 | |
114 | static __always_inline bool lockdep_enabled(void) |
115 | { |
116 | if (!debug_locks) |
117 | return false; |
118 | |
119 | if (this_cpu_read(lockdep_recursion)) |
120 | return false; |
121 | |
122 | if (current->lockdep_recursion) |
123 | return false; |
124 | |
125 | return true; |
126 | } |
127 | |
128 | /* |
129 | * lockdep_lock: protects the lockdep graph, the hashes and the |
130 | * class/list/hash allocators. |
131 | * |
132 | * This is one of the rare exceptions where it's justified |
133 | * to use a raw spinlock - we really dont want the spinlock |
134 | * code to recurse back into the lockdep code... |
135 | */ |
136 | static arch_spinlock_t __lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; |
137 | static struct task_struct *__owner; |
138 | |
139 | static inline void lockdep_lock(void) |
140 | { |
141 | DEBUG_LOCKS_WARN_ON(!irqs_disabled()); |
142 | |
143 | __this_cpu_inc(lockdep_recursion); |
144 | arch_spin_lock(&__lock); |
145 | __owner = current; |
146 | } |
147 | |
148 | static inline void lockdep_unlock(void) |
149 | { |
150 | DEBUG_LOCKS_WARN_ON(!irqs_disabled()); |
151 | |
152 | if (debug_locks && DEBUG_LOCKS_WARN_ON(__owner != current)) |
153 | return; |
154 | |
155 | __owner = NULL; |
156 | arch_spin_unlock(&__lock); |
157 | __this_cpu_dec(lockdep_recursion); |
158 | } |
159 | |
160 | static inline bool lockdep_assert_locked(void) |
161 | { |
162 | return DEBUG_LOCKS_WARN_ON(__owner != current); |
163 | } |
164 | |
165 | static struct task_struct *lockdep_selftest_task_struct; |
166 | |
167 | |
168 | static int graph_lock(void) |
169 | { |
170 | lockdep_lock(); |
171 | /* |
172 | * Make sure that if another CPU detected a bug while |
173 | * walking the graph we dont change it (while the other |
174 | * CPU is busy printing out stuff with the graph lock |
175 | * dropped already) |
176 | */ |
177 | if (!debug_locks) { |
178 | lockdep_unlock(); |
179 | return 0; |
180 | } |
181 | return 1; |
182 | } |
183 | |
184 | static inline void graph_unlock(void) |
185 | { |
186 | lockdep_unlock(); |
187 | } |
188 | |
189 | /* |
190 | * Turn lock debugging off and return with 0 if it was off already, |
191 | * and also release the graph lock: |
192 | */ |
193 | static inline int debug_locks_off_graph_unlock(void) |
194 | { |
195 | int ret = debug_locks_off(); |
196 | |
197 | lockdep_unlock(); |
198 | |
199 | return ret; |
200 | } |
201 | |
202 | unsigned long nr_list_entries; |
203 | static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES]; |
204 | static DECLARE_BITMAP(list_entries_in_use, MAX_LOCKDEP_ENTRIES); |
205 | |
206 | /* |
207 | * All data structures here are protected by the global debug_lock. |
208 | * |
209 | * nr_lock_classes is the number of elements of lock_classes[] that is |
210 | * in use. |
211 | */ |
212 | #define KEYHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1) |
213 | #define KEYHASH_SIZE (1UL << KEYHASH_BITS) |
214 | static struct hlist_head lock_keys_hash[KEYHASH_SIZE]; |
215 | unsigned long nr_lock_classes; |
216 | unsigned long nr_zapped_classes; |
217 | unsigned long max_lock_class_idx; |
218 | struct lock_class lock_classes[MAX_LOCKDEP_KEYS]; |
219 | DECLARE_BITMAP(lock_classes_in_use, MAX_LOCKDEP_KEYS); |
220 | |
221 | static inline struct lock_class *hlock_class(struct held_lock *hlock) |
222 | { |
223 | unsigned int class_idx = hlock->class_idx; |
224 | |
225 | /* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfield */ |
226 | barrier(); |
227 | |
228 | if (!test_bit(class_idx, lock_classes_in_use)) { |
229 | /* |
230 | * Someone passed in garbage, we give up. |
231 | */ |
232 | DEBUG_LOCKS_WARN_ON(1); |
233 | return NULL; |
234 | } |
235 | |
236 | /* |
237 | * At this point, if the passed hlock->class_idx is still garbage, |
238 | * we just have to live with it |
239 | */ |
240 | return lock_classes + class_idx; |
241 | } |
242 | |
243 | #ifdef CONFIG_LOCK_STAT |
244 | static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], cpu_lock_stats); |
245 | |
246 | static inline u64 lockstat_clock(void) |
247 | { |
248 | return local_clock(); |
249 | } |
250 | |
251 | static int lock_point(unsigned long points[], unsigned long ip) |
252 | { |
253 | int i; |
254 | |
255 | for (i = 0; i < LOCKSTAT_POINTS; i++) { |
256 | if (points[i] == 0) { |
257 | points[i] = ip; |
258 | break; |
259 | } |
260 | if (points[i] == ip) |
261 | break; |
262 | } |
263 | |
264 | return i; |
265 | } |
266 | |
267 | static void lock_time_inc(struct lock_time *lt, u64 time) |
268 | { |
269 | if (time > lt->max) |
270 | lt->max = time; |
271 | |
272 | if (time < lt->min || !lt->nr) |
273 | lt->min = time; |
274 | |
275 | lt->total += time; |
276 | lt->nr++; |
277 | } |
278 | |
279 | static inline void lock_time_add(struct lock_time *src, struct lock_time *dst) |
280 | { |
281 | if (!src->nr) |
282 | return; |
283 | |
284 | if (src->max > dst->max) |
285 | dst->max = src->max; |
286 | |
287 | if (src->min < dst->min || !dst->nr) |
288 | dst->min = src->min; |
289 | |
290 | dst->total += src->total; |
291 | dst->nr += src->nr; |
292 | } |
293 | |
294 | struct lock_class_stats lock_stats(struct lock_class *class) |
295 | { |
296 | struct lock_class_stats stats; |
297 | int cpu, i; |
298 | |
299 | memset(&stats, 0, sizeof(struct lock_class_stats)); |
300 | for_each_possible_cpu(cpu) { |
301 | struct lock_class_stats *pcs = |
302 | &per_cpu(cpu_lock_stats, cpu)[class - lock_classes]; |
303 | |
304 | for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++) |
305 | stats.contention_point[i] += pcs->contention_point[i]; |
306 | |
307 | for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++) |
308 | stats.contending_point[i] += pcs->contending_point[i]; |
309 | |
310 | lock_time_add(src: &pcs->read_waittime, dst: &stats.read_waittime); |
311 | lock_time_add(src: &pcs->write_waittime, dst: &stats.write_waittime); |
312 | |
313 | lock_time_add(src: &pcs->read_holdtime, dst: &stats.read_holdtime); |
314 | lock_time_add(src: &pcs->write_holdtime, dst: &stats.write_holdtime); |
315 | |
316 | for (i = 0; i < ARRAY_SIZE(stats.bounces); i++) |
317 | stats.bounces[i] += pcs->bounces[i]; |
318 | } |
319 | |
320 | return stats; |
321 | } |
322 | |
323 | void clear_lock_stats(struct lock_class *class) |
324 | { |
325 | int cpu; |
326 | |
327 | for_each_possible_cpu(cpu) { |
328 | struct lock_class_stats *cpu_stats = |
329 | &per_cpu(cpu_lock_stats, cpu)[class - lock_classes]; |
330 | |
331 | memset(cpu_stats, 0, sizeof(struct lock_class_stats)); |
332 | } |
333 | memset(class->contention_point, 0, sizeof(class->contention_point)); |
334 | memset(class->contending_point, 0, sizeof(class->contending_point)); |
335 | } |
336 | |
337 | static struct lock_class_stats *get_lock_stats(struct lock_class *class) |
338 | { |
339 | return &this_cpu_ptr(cpu_lock_stats)[class - lock_classes]; |
340 | } |
341 | |
342 | static void lock_release_holdtime(struct held_lock *hlock) |
343 | { |
344 | struct lock_class_stats *stats; |
345 | u64 holdtime; |
346 | |
347 | if (!lock_stat) |
348 | return; |
349 | |
350 | holdtime = lockstat_clock() - hlock->holdtime_stamp; |
351 | |
352 | stats = get_lock_stats(class: hlock_class(hlock)); |
353 | if (hlock->read) |
354 | lock_time_inc(lt: &stats->read_holdtime, time: holdtime); |
355 | else |
356 | lock_time_inc(lt: &stats->write_holdtime, time: holdtime); |
357 | } |
358 | #else |
359 | static inline void lock_release_holdtime(struct held_lock *hlock) |
360 | { |
361 | } |
362 | #endif |
363 | |
364 | /* |
365 | * We keep a global list of all lock classes. The list is only accessed with |
366 | * the lockdep spinlock lock held. free_lock_classes is a list with free |
367 | * elements. These elements are linked together by the lock_entry member in |
368 | * struct lock_class. |
369 | */ |
370 | static LIST_HEAD(all_lock_classes); |
371 | static LIST_HEAD(free_lock_classes); |
372 | |
373 | /** |
374 | * struct pending_free - information about data structures about to be freed |
375 | * @zapped: Head of a list with struct lock_class elements. |
376 | * @lock_chains_being_freed: Bitmap that indicates which lock_chains[] elements |
377 | * are about to be freed. |
378 | */ |
379 | struct pending_free { |
380 | struct list_head zapped; |
381 | DECLARE_BITMAP(lock_chains_being_freed, MAX_LOCKDEP_CHAINS); |
382 | }; |
383 | |
384 | /** |
385 | * struct delayed_free - data structures used for delayed freeing |
386 | * |
387 | * A data structure for delayed freeing of data structures that may be |
388 | * accessed by RCU readers at the time these were freed. |
389 | * |
390 | * @rcu_head: Used to schedule an RCU callback for freeing data structures. |
391 | * @index: Index of @pf to which freed data structures are added. |
392 | * @scheduled: Whether or not an RCU callback has been scheduled. |
393 | * @pf: Array with information about data structures about to be freed. |
394 | */ |
395 | static struct delayed_free { |
396 | struct rcu_head rcu_head; |
397 | int index; |
398 | int scheduled; |
399 | struct pending_free pf[2]; |
400 | } delayed_free; |
401 | |
402 | /* |
403 | * The lockdep classes are in a hash-table as well, for fast lookup: |
404 | */ |
405 | #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1) |
406 | #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS) |
407 | #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS) |
408 | #define classhashentry(key) (classhash_table + __classhashfn((key))) |
409 | |
410 | static struct hlist_head classhash_table[CLASSHASH_SIZE]; |
411 | |
412 | /* |
413 | * We put the lock dependency chains into a hash-table as well, to cache |
414 | * their existence: |
415 | */ |
416 | #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1) |
417 | #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS) |
418 | #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS) |
419 | #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain))) |
420 | |
421 | static struct hlist_head chainhash_table[CHAINHASH_SIZE]; |
422 | |
423 | /* |
424 | * the id of held_lock |
425 | */ |
426 | static inline u16 hlock_id(struct held_lock *hlock) |
427 | { |
428 | BUILD_BUG_ON(MAX_LOCKDEP_KEYS_BITS + 2 > 16); |
429 | |
430 | return (hlock->class_idx | (hlock->read << MAX_LOCKDEP_KEYS_BITS)); |
431 | } |
432 | |
433 | static inline unsigned int chain_hlock_class_idx(u16 hlock_id) |
434 | { |
435 | return hlock_id & (MAX_LOCKDEP_KEYS - 1); |
436 | } |
437 | |
438 | /* |
439 | * The hash key of the lock dependency chains is a hash itself too: |
440 | * it's a hash of all locks taken up to that lock, including that lock. |
441 | * It's a 64-bit hash, because it's important for the keys to be |
442 | * unique. |
443 | */ |
444 | static inline u64 iterate_chain_key(u64 key, u32 idx) |
445 | { |
446 | u32 k0 = key, k1 = key >> 32; |
447 | |
448 | __jhash_mix(idx, k0, k1); /* Macro that modifies arguments! */ |
449 | |
450 | return k0 | (u64)k1 << 32; |
451 | } |
452 | |
453 | void lockdep_init_task(struct task_struct *task) |
454 | { |
455 | task->lockdep_depth = 0; /* no locks held yet */ |
456 | task->curr_chain_key = INITIAL_CHAIN_KEY; |
457 | task->lockdep_recursion = 0; |
458 | } |
459 | |
460 | static __always_inline void lockdep_recursion_inc(void) |
461 | { |
462 | __this_cpu_inc(lockdep_recursion); |
463 | } |
464 | |
465 | static __always_inline void lockdep_recursion_finish(void) |
466 | { |
467 | if (WARN_ON_ONCE(__this_cpu_dec_return(lockdep_recursion))) |
468 | __this_cpu_write(lockdep_recursion, 0); |
469 | } |
470 | |
471 | void lockdep_set_selftest_task(struct task_struct *task) |
472 | { |
473 | lockdep_selftest_task_struct = task; |
474 | } |
475 | |
476 | /* |
477 | * Debugging switches: |
478 | */ |
479 | |
480 | #define VERBOSE 0 |
481 | #define VERY_VERBOSE 0 |
482 | |
483 | #if VERBOSE |
484 | # define HARDIRQ_VERBOSE 1 |
485 | # define SOFTIRQ_VERBOSE 1 |
486 | #else |
487 | # define HARDIRQ_VERBOSE 0 |
488 | # define SOFTIRQ_VERBOSE 0 |
489 | #endif |
490 | |
491 | #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE |
492 | /* |
493 | * Quick filtering for interesting events: |
494 | */ |
495 | static int class_filter(struct lock_class *class) |
496 | { |
497 | #if 0 |
498 | /* Example */ |
499 | if (class->name_version == 1 && |
500 | !strcmp(class->name, "lockname" )) |
501 | return 1; |
502 | if (class->name_version == 1 && |
503 | !strcmp(class->name, "&struct->lockfield" )) |
504 | return 1; |
505 | #endif |
506 | /* Filter everything else. 1 would be to allow everything else */ |
507 | return 0; |
508 | } |
509 | #endif |
510 | |
511 | static int verbose(struct lock_class *class) |
512 | { |
513 | #if VERBOSE |
514 | return class_filter(class); |
515 | #endif |
516 | return 0; |
517 | } |
518 | |
519 | static void print_lockdep_off(const char *bug_msg) |
520 | { |
521 | printk(KERN_DEBUG "%s\n" , bug_msg); |
522 | printk(KERN_DEBUG "turning off the locking correctness validator.\n" ); |
523 | #ifdef CONFIG_LOCK_STAT |
524 | printk(KERN_DEBUG "Please attach the output of /proc/lock_stat to the bug report\n" ); |
525 | #endif |
526 | } |
527 | |
528 | unsigned long nr_stack_trace_entries; |
529 | |
530 | #ifdef CONFIG_PROVE_LOCKING |
531 | /** |
532 | * struct lock_trace - single stack backtrace |
533 | * @hash_entry: Entry in a stack_trace_hash[] list. |
534 | * @hash: jhash() of @entries. |
535 | * @nr_entries: Number of entries in @entries. |
536 | * @entries: Actual stack backtrace. |
537 | */ |
538 | struct lock_trace { |
539 | struct hlist_node hash_entry; |
540 | u32 hash; |
541 | u32 nr_entries; |
542 | unsigned long entries[] __aligned(sizeof(unsigned long)); |
543 | }; |
544 | #define LOCK_TRACE_SIZE_IN_LONGS \ |
545 | (sizeof(struct lock_trace) / sizeof(unsigned long)) |
546 | /* |
547 | * Stack-trace: sequence of lock_trace structures. Protected by the graph_lock. |
548 | */ |
549 | static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES]; |
550 | static struct hlist_head stack_trace_hash[STACK_TRACE_HASH_SIZE]; |
551 | |
552 | static bool traces_identical(struct lock_trace *t1, struct lock_trace *t2) |
553 | { |
554 | return t1->hash == t2->hash && t1->nr_entries == t2->nr_entries && |
555 | memcmp(p: t1->entries, q: t2->entries, |
556 | size: t1->nr_entries * sizeof(t1->entries[0])) == 0; |
557 | } |
558 | |
559 | static struct lock_trace *save_trace(void) |
560 | { |
561 | struct lock_trace *trace, *t2; |
562 | struct hlist_head *hash_head; |
563 | u32 hash; |
564 | int max_entries; |
565 | |
566 | BUILD_BUG_ON_NOT_POWER_OF_2(STACK_TRACE_HASH_SIZE); |
567 | BUILD_BUG_ON(LOCK_TRACE_SIZE_IN_LONGS >= MAX_STACK_TRACE_ENTRIES); |
568 | |
569 | trace = (struct lock_trace *)(stack_trace + nr_stack_trace_entries); |
570 | max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries - |
571 | LOCK_TRACE_SIZE_IN_LONGS; |
572 | |
573 | if (max_entries <= 0) { |
574 | if (!debug_locks_off_graph_unlock()) |
575 | return NULL; |
576 | |
577 | print_lockdep_off(bug_msg: "BUG: MAX_STACK_TRACE_ENTRIES too low!" ); |
578 | dump_stack(); |
579 | |
580 | return NULL; |
581 | } |
582 | trace->nr_entries = stack_trace_save(store: trace->entries, size: max_entries, skipnr: 3); |
583 | |
584 | hash = jhash(key: trace->entries, length: trace->nr_entries * |
585 | sizeof(trace->entries[0]), initval: 0); |
586 | trace->hash = hash; |
587 | hash_head = stack_trace_hash + (hash & (STACK_TRACE_HASH_SIZE - 1)); |
588 | hlist_for_each_entry(t2, hash_head, hash_entry) { |
589 | if (traces_identical(t1: trace, t2)) |
590 | return t2; |
591 | } |
592 | nr_stack_trace_entries += LOCK_TRACE_SIZE_IN_LONGS + trace->nr_entries; |
593 | hlist_add_head(n: &trace->hash_entry, h: hash_head); |
594 | |
595 | return trace; |
596 | } |
597 | |
598 | /* Return the number of stack traces in the stack_trace[] array. */ |
599 | u64 lockdep_stack_trace_count(void) |
600 | { |
601 | struct lock_trace *trace; |
602 | u64 c = 0; |
603 | int i; |
604 | |
605 | for (i = 0; i < ARRAY_SIZE(stack_trace_hash); i++) { |
606 | hlist_for_each_entry(trace, &stack_trace_hash[i], hash_entry) { |
607 | c++; |
608 | } |
609 | } |
610 | |
611 | return c; |
612 | } |
613 | |
614 | /* Return the number of stack hash chains that have at least one stack trace. */ |
615 | u64 lockdep_stack_hash_count(void) |
616 | { |
617 | u64 c = 0; |
618 | int i; |
619 | |
620 | for (i = 0; i < ARRAY_SIZE(stack_trace_hash); i++) |
621 | if (!hlist_empty(h: &stack_trace_hash[i])) |
622 | c++; |
623 | |
624 | return c; |
625 | } |
626 | #endif |
627 | |
628 | unsigned int nr_hardirq_chains; |
629 | unsigned int nr_softirq_chains; |
630 | unsigned int nr_process_chains; |
631 | unsigned int max_lockdep_depth; |
632 | |
633 | #ifdef CONFIG_DEBUG_LOCKDEP |
634 | /* |
635 | * Various lockdep statistics: |
636 | */ |
637 | DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats); |
638 | #endif |
639 | |
640 | #ifdef CONFIG_PROVE_LOCKING |
641 | /* |
642 | * Locking printouts: |
643 | */ |
644 | |
645 | #define __USAGE(__STATE) \ |
646 | [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \ |
647 | [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \ |
648 | [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\ |
649 | [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R", |
650 | |
651 | static const char *usage_str[] = |
652 | { |
653 | #define LOCKDEP_STATE(__STATE) __USAGE(__STATE) |
654 | #include "lockdep_states.h" |
655 | #undef LOCKDEP_STATE |
656 | [LOCK_USED] = "INITIAL USE" , |
657 | [LOCK_USED_READ] = "INITIAL READ USE" , |
658 | /* abused as string storage for verify_lock_unused() */ |
659 | [LOCK_USAGE_STATES] = "IN-NMI" , |
660 | }; |
661 | #endif |
662 | |
663 | const char *__get_key_name(const struct lockdep_subclass_key *key, char *str) |
664 | { |
665 | return kallsyms_lookup(addr: (unsigned long)key, NULL, NULL, NULL, namebuf: str); |
666 | } |
667 | |
668 | static inline unsigned long lock_flag(enum lock_usage_bit bit) |
669 | { |
670 | return 1UL << bit; |
671 | } |
672 | |
673 | static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit) |
674 | { |
675 | /* |
676 | * The usage character defaults to '.' (i.e., irqs disabled and not in |
677 | * irq context), which is the safest usage category. |
678 | */ |
679 | char c = '.'; |
680 | |
681 | /* |
682 | * The order of the following usage checks matters, which will |
683 | * result in the outcome character as follows: |
684 | * |
685 | * - '+': irq is enabled and not in irq context |
686 | * - '-': in irq context and irq is disabled |
687 | * - '?': in irq context and irq is enabled |
688 | */ |
689 | if (class->usage_mask & lock_flag(bit: bit + LOCK_USAGE_DIR_MASK)) { |
690 | c = '+'; |
691 | if (class->usage_mask & lock_flag(bit)) |
692 | c = '?'; |
693 | } else if (class->usage_mask & lock_flag(bit)) |
694 | c = '-'; |
695 | |
696 | return c; |
697 | } |
698 | |
699 | void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS]) |
700 | { |
701 | int i = 0; |
702 | |
703 | #define LOCKDEP_STATE(__STATE) \ |
704 | usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \ |
705 | usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ); |
706 | #include "lockdep_states.h" |
707 | #undef LOCKDEP_STATE |
708 | |
709 | usage[i] = '\0'; |
710 | } |
711 | |
712 | static void __print_lock_name(struct held_lock *hlock, struct lock_class *class) |
713 | { |
714 | char str[KSYM_NAME_LEN]; |
715 | const char *name; |
716 | |
717 | name = class->name; |
718 | if (!name) { |
719 | name = __get_key_name(key: class->key, str); |
720 | printk(KERN_CONT "%s" , name); |
721 | } else { |
722 | printk(KERN_CONT "%s" , name); |
723 | if (class->name_version > 1) |
724 | printk(KERN_CONT "#%d" , class->name_version); |
725 | if (class->subclass) |
726 | printk(KERN_CONT "/%d" , class->subclass); |
727 | if (hlock && class->print_fn) |
728 | class->print_fn(hlock->instance); |
729 | } |
730 | } |
731 | |
732 | static void print_lock_name(struct held_lock *hlock, struct lock_class *class) |
733 | { |
734 | char usage[LOCK_USAGE_CHARS]; |
735 | |
736 | get_usage_chars(class, usage); |
737 | |
738 | printk(KERN_CONT " (" ); |
739 | __print_lock_name(hlock, class); |
740 | printk(KERN_CONT "){%s}-{%d:%d}" , usage, |
741 | class->wait_type_outer ?: class->wait_type_inner, |
742 | class->wait_type_inner); |
743 | } |
744 | |
745 | static void print_lockdep_cache(struct lockdep_map *lock) |
746 | { |
747 | const char *name; |
748 | char str[KSYM_NAME_LEN]; |
749 | |
750 | name = lock->name; |
751 | if (!name) |
752 | name = __get_key_name(key: lock->key->subkeys, str); |
753 | |
754 | printk(KERN_CONT "%s" , name); |
755 | } |
756 | |
757 | static void print_lock(struct held_lock *hlock) |
758 | { |
759 | /* |
760 | * We can be called locklessly through debug_show_all_locks() so be |
761 | * extra careful, the hlock might have been released and cleared. |
762 | * |
763 | * If this indeed happens, lets pretend it does not hurt to continue |
764 | * to print the lock unless the hlock class_idx does not point to a |
765 | * registered class. The rationale here is: since we don't attempt |
766 | * to distinguish whether we are in this situation, if it just |
767 | * happened we can't count on class_idx to tell either. |
768 | */ |
769 | struct lock_class *lock = hlock_class(hlock); |
770 | |
771 | if (!lock) { |
772 | printk(KERN_CONT "<RELEASED>\n" ); |
773 | return; |
774 | } |
775 | |
776 | printk(KERN_CONT "%px" , hlock->instance); |
777 | print_lock_name(hlock, class: lock); |
778 | printk(KERN_CONT ", at: %pS\n" , (void *)hlock->acquire_ip); |
779 | } |
780 | |
781 | static void lockdep_print_held_locks(struct task_struct *p) |
782 | { |
783 | int i, depth = READ_ONCE(p->lockdep_depth); |
784 | |
785 | if (!depth) |
786 | printk("no locks held by %s/%d.\n" , p->comm, task_pid_nr(p)); |
787 | else |
788 | printk("%d lock%s held by %s/%d:\n" , depth, |
789 | depth > 1 ? "s" : "" , p->comm, task_pid_nr(p)); |
790 | /* |
791 | * It's not reliable to print a task's held locks if it's not sleeping |
792 | * and it's not the current task. |
793 | */ |
794 | if (p != current && task_is_running(p)) |
795 | return; |
796 | for (i = 0; i < depth; i++) { |
797 | printk(" #%d: " , i); |
798 | print_lock(hlock: p->held_locks + i); |
799 | } |
800 | } |
801 | |
802 | static void print_kernel_ident(void) |
803 | { |
804 | printk("%s %.*s %s\n" , init_utsname()->release, |
805 | (int)strcspn(init_utsname()->version, " " ), |
806 | init_utsname()->version, |
807 | print_tainted()); |
808 | } |
809 | |
810 | static int very_verbose(struct lock_class *class) |
811 | { |
812 | #if VERY_VERBOSE |
813 | return class_filter(class); |
814 | #endif |
815 | return 0; |
816 | } |
817 | |
818 | /* |
819 | * Is this the address of a static object: |
820 | */ |
821 | #ifdef __KERNEL__ |
822 | static int static_obj(const void *obj) |
823 | { |
824 | unsigned long addr = (unsigned long) obj; |
825 | |
826 | if (is_kernel_core_data(addr)) |
827 | return 1; |
828 | |
829 | /* |
830 | * keys are allowed in the __ro_after_init section. |
831 | */ |
832 | if (is_kernel_rodata(addr)) |
833 | return 1; |
834 | |
835 | /* |
836 | * in initdata section and used during bootup only? |
837 | * NOTE: On some platforms the initdata section is |
838 | * outside of the _stext ... _end range. |
839 | */ |
840 | if (system_state < SYSTEM_FREEING_INITMEM && |
841 | init_section_contains(virt: (void *)addr, size: 1)) |
842 | return 1; |
843 | |
844 | /* |
845 | * in-kernel percpu var? |
846 | */ |
847 | if (is_kernel_percpu_address(addr)) |
848 | return 1; |
849 | |
850 | /* |
851 | * module static or percpu var? |
852 | */ |
853 | return is_module_address(addr) || is_module_percpu_address(addr); |
854 | } |
855 | #endif |
856 | |
857 | /* |
858 | * To make lock name printouts unique, we calculate a unique |
859 | * class->name_version generation counter. The caller must hold the graph |
860 | * lock. |
861 | */ |
862 | static int count_matching_names(struct lock_class *new_class) |
863 | { |
864 | struct lock_class *class; |
865 | int count = 0; |
866 | |
867 | if (!new_class->name) |
868 | return 0; |
869 | |
870 | list_for_each_entry(class, &all_lock_classes, lock_entry) { |
871 | if (new_class->key - new_class->subclass == class->key) |
872 | return class->name_version; |
873 | if (class->name && !strcmp(class->name, new_class->name)) |
874 | count = max(count, class->name_version); |
875 | } |
876 | |
877 | return count + 1; |
878 | } |
879 | |
880 | /* used from NMI context -- must be lockless */ |
881 | static noinstr struct lock_class * |
882 | look_up_lock_class(const struct lockdep_map *lock, unsigned int subclass) |
883 | { |
884 | struct lockdep_subclass_key *key; |
885 | struct hlist_head *hash_head; |
886 | struct lock_class *class; |
887 | |
888 | if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) { |
889 | instrumentation_begin(); |
890 | debug_locks_off(); |
891 | printk(KERN_ERR |
892 | "BUG: looking up invalid subclass: %u\n" , subclass); |
893 | printk(KERN_ERR |
894 | "turning off the locking correctness validator.\n" ); |
895 | dump_stack(); |
896 | instrumentation_end(); |
897 | return NULL; |
898 | } |
899 | |
900 | /* |
901 | * If it is not initialised then it has never been locked, |
902 | * so it won't be present in the hash table. |
903 | */ |
904 | if (unlikely(!lock->key)) |
905 | return NULL; |
906 | |
907 | /* |
908 | * NOTE: the class-key must be unique. For dynamic locks, a static |
909 | * lock_class_key variable is passed in through the mutex_init() |
910 | * (or spin_lock_init()) call - which acts as the key. For static |
911 | * locks we use the lock object itself as the key. |
912 | */ |
913 | BUILD_BUG_ON(sizeof(struct lock_class_key) > |
914 | sizeof(struct lockdep_map)); |
915 | |
916 | key = lock->key->subkeys + subclass; |
917 | |
918 | hash_head = classhashentry(key); |
919 | |
920 | /* |
921 | * We do an RCU walk of the hash, see lockdep_free_key_range(). |
922 | */ |
923 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
924 | return NULL; |
925 | |
926 | hlist_for_each_entry_rcu_notrace(class, hash_head, hash_entry) { |
927 | if (class->key == key) { |
928 | /* |
929 | * Huh! same key, different name? Did someone trample |
930 | * on some memory? We're most confused. |
931 | */ |
932 | WARN_ONCE(class->name != lock->name && |
933 | lock->key != &__lockdep_no_validate__, |
934 | "Looking for class \"%s\" with key %ps, but found a different class \"%s\" with the same key\n" , |
935 | lock->name, lock->key, class->name); |
936 | return class; |
937 | } |
938 | } |
939 | |
940 | return NULL; |
941 | } |
942 | |
943 | /* |
944 | * Static locks do not have their class-keys yet - for them the key is |
945 | * the lock object itself. If the lock is in the per cpu area, the |
946 | * canonical address of the lock (per cpu offset removed) is used. |
947 | */ |
948 | static bool assign_lock_key(struct lockdep_map *lock) |
949 | { |
950 | unsigned long can_addr, addr = (unsigned long)lock; |
951 | |
952 | #ifdef __KERNEL__ |
953 | /* |
954 | * lockdep_free_key_range() assumes that struct lock_class_key |
955 | * objects do not overlap. Since we use the address of lock |
956 | * objects as class key for static objects, check whether the |
957 | * size of lock_class_key objects does not exceed the size of |
958 | * the smallest lock object. |
959 | */ |
960 | BUILD_BUG_ON(sizeof(struct lock_class_key) > sizeof(raw_spinlock_t)); |
961 | #endif |
962 | |
963 | if (__is_kernel_percpu_address(addr, can_addr: &can_addr)) |
964 | lock->key = (void *)can_addr; |
965 | else if (__is_module_percpu_address(addr, can_addr: &can_addr)) |
966 | lock->key = (void *)can_addr; |
967 | else if (static_obj(obj: lock)) |
968 | lock->key = (void *)lock; |
969 | else { |
970 | /* Debug-check: all keys must be persistent! */ |
971 | debug_locks_off(); |
972 | pr_err("INFO: trying to register non-static key.\n" ); |
973 | pr_err("The code is fine but needs lockdep annotation, or maybe\n" ); |
974 | pr_err("you didn't initialize this object before use?\n" ); |
975 | pr_err("turning off the locking correctness validator.\n" ); |
976 | dump_stack(); |
977 | return false; |
978 | } |
979 | |
980 | return true; |
981 | } |
982 | |
983 | #ifdef CONFIG_DEBUG_LOCKDEP |
984 | |
985 | /* Check whether element @e occurs in list @h */ |
986 | static bool in_list(struct list_head *e, struct list_head *h) |
987 | { |
988 | struct list_head *f; |
989 | |
990 | list_for_each(f, h) { |
991 | if (e == f) |
992 | return true; |
993 | } |
994 | |
995 | return false; |
996 | } |
997 | |
998 | /* |
999 | * Check whether entry @e occurs in any of the locks_after or locks_before |
1000 | * lists. |
1001 | */ |
1002 | static bool in_any_class_list(struct list_head *e) |
1003 | { |
1004 | struct lock_class *class; |
1005 | int i; |
1006 | |
1007 | for (i = 0; i < ARRAY_SIZE(lock_classes); i++) { |
1008 | class = &lock_classes[i]; |
1009 | if (in_list(e, h: &class->locks_after) || |
1010 | in_list(e, h: &class->locks_before)) |
1011 | return true; |
1012 | } |
1013 | return false; |
1014 | } |
1015 | |
1016 | static bool class_lock_list_valid(struct lock_class *c, struct list_head *h) |
1017 | { |
1018 | struct lock_list *e; |
1019 | |
1020 | list_for_each_entry(e, h, entry) { |
1021 | if (e->links_to != c) { |
1022 | printk(KERN_INFO "class %s: mismatch for lock entry %ld; class %s <> %s" , |
1023 | c->name ? : "(?)" , |
1024 | (unsigned long)(e - list_entries), |
1025 | e->links_to && e->links_to->name ? |
1026 | e->links_to->name : "(?)" , |
1027 | e->class && e->class->name ? e->class->name : |
1028 | "(?)" ); |
1029 | return false; |
1030 | } |
1031 | } |
1032 | return true; |
1033 | } |
1034 | |
1035 | #ifdef CONFIG_PROVE_LOCKING |
1036 | static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS]; |
1037 | #endif |
1038 | |
1039 | static bool check_lock_chain_key(struct lock_chain *chain) |
1040 | { |
1041 | #ifdef CONFIG_PROVE_LOCKING |
1042 | u64 chain_key = INITIAL_CHAIN_KEY; |
1043 | int i; |
1044 | |
1045 | for (i = chain->base; i < chain->base + chain->depth; i++) |
1046 | chain_key = iterate_chain_key(key: chain_key, idx: chain_hlocks[i]); |
1047 | /* |
1048 | * The 'unsigned long long' casts avoid that a compiler warning |
1049 | * is reported when building tools/lib/lockdep. |
1050 | */ |
1051 | if (chain->chain_key != chain_key) { |
1052 | printk(KERN_INFO "chain %lld: key %#llx <> %#llx\n" , |
1053 | (unsigned long long)(chain - lock_chains), |
1054 | (unsigned long long)chain->chain_key, |
1055 | (unsigned long long)chain_key); |
1056 | return false; |
1057 | } |
1058 | #endif |
1059 | return true; |
1060 | } |
1061 | |
1062 | static bool in_any_zapped_class_list(struct lock_class *class) |
1063 | { |
1064 | struct pending_free *pf; |
1065 | int i; |
1066 | |
1067 | for (i = 0, pf = delayed_free.pf; i < ARRAY_SIZE(delayed_free.pf); i++, pf++) { |
1068 | if (in_list(e: &class->lock_entry, h: &pf->zapped)) |
1069 | return true; |
1070 | } |
1071 | |
1072 | return false; |
1073 | } |
1074 | |
1075 | static bool __check_data_structures(void) |
1076 | { |
1077 | struct lock_class *class; |
1078 | struct lock_chain *chain; |
1079 | struct hlist_head *head; |
1080 | struct lock_list *e; |
1081 | int i; |
1082 | |
1083 | /* Check whether all classes occur in a lock list. */ |
1084 | for (i = 0; i < ARRAY_SIZE(lock_classes); i++) { |
1085 | class = &lock_classes[i]; |
1086 | if (!in_list(e: &class->lock_entry, h: &all_lock_classes) && |
1087 | !in_list(e: &class->lock_entry, h: &free_lock_classes) && |
1088 | !in_any_zapped_class_list(class)) { |
1089 | printk(KERN_INFO "class %px/%s is not in any class list\n" , |
1090 | class, class->name ? : "(?)" ); |
1091 | return false; |
1092 | } |
1093 | } |
1094 | |
1095 | /* Check whether all classes have valid lock lists. */ |
1096 | for (i = 0; i < ARRAY_SIZE(lock_classes); i++) { |
1097 | class = &lock_classes[i]; |
1098 | if (!class_lock_list_valid(c: class, h: &class->locks_before)) |
1099 | return false; |
1100 | if (!class_lock_list_valid(c: class, h: &class->locks_after)) |
1101 | return false; |
1102 | } |
1103 | |
1104 | /* Check the chain_key of all lock chains. */ |
1105 | for (i = 0; i < ARRAY_SIZE(chainhash_table); i++) { |
1106 | head = chainhash_table + i; |
1107 | hlist_for_each_entry_rcu(chain, head, entry) { |
1108 | if (!check_lock_chain_key(chain)) |
1109 | return false; |
1110 | } |
1111 | } |
1112 | |
1113 | /* |
1114 | * Check whether all list entries that are in use occur in a class |
1115 | * lock list. |
1116 | */ |
1117 | for_each_set_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) { |
1118 | e = list_entries + i; |
1119 | if (!in_any_class_list(e: &e->entry)) { |
1120 | printk(KERN_INFO "list entry %d is not in any class list; class %s <> %s\n" , |
1121 | (unsigned int)(e - list_entries), |
1122 | e->class->name ? : "(?)" , |
1123 | e->links_to->name ? : "(?)" ); |
1124 | return false; |
1125 | } |
1126 | } |
1127 | |
1128 | /* |
1129 | * Check whether all list entries that are not in use do not occur in |
1130 | * a class lock list. |
1131 | */ |
1132 | for_each_clear_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) { |
1133 | e = list_entries + i; |
1134 | if (in_any_class_list(e: &e->entry)) { |
1135 | printk(KERN_INFO "list entry %d occurs in a class list; class %s <> %s\n" , |
1136 | (unsigned int)(e - list_entries), |
1137 | e->class && e->class->name ? e->class->name : |
1138 | "(?)" , |
1139 | e->links_to && e->links_to->name ? |
1140 | e->links_to->name : "(?)" ); |
1141 | return false; |
1142 | } |
1143 | } |
1144 | |
1145 | return true; |
1146 | } |
1147 | |
1148 | int check_consistency = 0; |
1149 | module_param(check_consistency, int, 0644); |
1150 | |
1151 | static void check_data_structures(void) |
1152 | { |
1153 | static bool once = false; |
1154 | |
1155 | if (check_consistency && !once) { |
1156 | if (!__check_data_structures()) { |
1157 | once = true; |
1158 | WARN_ON(once); |
1159 | } |
1160 | } |
1161 | } |
1162 | |
1163 | #else /* CONFIG_DEBUG_LOCKDEP */ |
1164 | |
1165 | static inline void check_data_structures(void) { } |
1166 | |
1167 | #endif /* CONFIG_DEBUG_LOCKDEP */ |
1168 | |
1169 | static void init_chain_block_buckets(void); |
1170 | |
1171 | /* |
1172 | * Initialize the lock_classes[] array elements, the free_lock_classes list |
1173 | * and also the delayed_free structure. |
1174 | */ |
1175 | static void init_data_structures_once(void) |
1176 | { |
1177 | static bool __read_mostly ds_initialized, rcu_head_initialized; |
1178 | int i; |
1179 | |
1180 | if (likely(rcu_head_initialized)) |
1181 | return; |
1182 | |
1183 | if (system_state >= SYSTEM_SCHEDULING) { |
1184 | init_rcu_head(head: &delayed_free.rcu_head); |
1185 | rcu_head_initialized = true; |
1186 | } |
1187 | |
1188 | if (ds_initialized) |
1189 | return; |
1190 | |
1191 | ds_initialized = true; |
1192 | |
1193 | INIT_LIST_HEAD(list: &delayed_free.pf[0].zapped); |
1194 | INIT_LIST_HEAD(list: &delayed_free.pf[1].zapped); |
1195 | |
1196 | for (i = 0; i < ARRAY_SIZE(lock_classes); i++) { |
1197 | list_add_tail(new: &lock_classes[i].lock_entry, head: &free_lock_classes); |
1198 | INIT_LIST_HEAD(list: &lock_classes[i].locks_after); |
1199 | INIT_LIST_HEAD(list: &lock_classes[i].locks_before); |
1200 | } |
1201 | init_chain_block_buckets(); |
1202 | } |
1203 | |
1204 | static inline struct hlist_head *keyhashentry(const struct lock_class_key *key) |
1205 | { |
1206 | unsigned long hash = hash_long((uintptr_t)key, KEYHASH_BITS); |
1207 | |
1208 | return lock_keys_hash + hash; |
1209 | } |
1210 | |
1211 | /* Register a dynamically allocated key. */ |
1212 | void lockdep_register_key(struct lock_class_key *key) |
1213 | { |
1214 | struct hlist_head *hash_head; |
1215 | struct lock_class_key *k; |
1216 | unsigned long flags; |
1217 | |
1218 | if (WARN_ON_ONCE(static_obj(key))) |
1219 | return; |
1220 | hash_head = keyhashentry(key); |
1221 | |
1222 | raw_local_irq_save(flags); |
1223 | if (!graph_lock()) |
1224 | goto restore_irqs; |
1225 | hlist_for_each_entry_rcu(k, hash_head, hash_entry) { |
1226 | if (WARN_ON_ONCE(k == key)) |
1227 | goto out_unlock; |
1228 | } |
1229 | hlist_add_head_rcu(n: &key->hash_entry, h: hash_head); |
1230 | out_unlock: |
1231 | graph_unlock(); |
1232 | restore_irqs: |
1233 | raw_local_irq_restore(flags); |
1234 | } |
1235 | EXPORT_SYMBOL_GPL(lockdep_register_key); |
1236 | |
1237 | /* Check whether a key has been registered as a dynamic key. */ |
1238 | static bool is_dynamic_key(const struct lock_class_key *key) |
1239 | { |
1240 | struct hlist_head *hash_head; |
1241 | struct lock_class_key *k; |
1242 | bool found = false; |
1243 | |
1244 | if (WARN_ON_ONCE(static_obj(key))) |
1245 | return false; |
1246 | |
1247 | /* |
1248 | * If lock debugging is disabled lock_keys_hash[] may contain |
1249 | * pointers to memory that has already been freed. Avoid triggering |
1250 | * a use-after-free in that case by returning early. |
1251 | */ |
1252 | if (!debug_locks) |
1253 | return true; |
1254 | |
1255 | hash_head = keyhashentry(key); |
1256 | |
1257 | rcu_read_lock(); |
1258 | hlist_for_each_entry_rcu(k, hash_head, hash_entry) { |
1259 | if (k == key) { |
1260 | found = true; |
1261 | break; |
1262 | } |
1263 | } |
1264 | rcu_read_unlock(); |
1265 | |
1266 | return found; |
1267 | } |
1268 | |
1269 | /* |
1270 | * Register a lock's class in the hash-table, if the class is not present |
1271 | * yet. Otherwise we look it up. We cache the result in the lock object |
1272 | * itself, so actual lookup of the hash should be once per lock object. |
1273 | */ |
1274 | static struct lock_class * |
1275 | register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force) |
1276 | { |
1277 | struct lockdep_subclass_key *key; |
1278 | struct hlist_head *hash_head; |
1279 | struct lock_class *class; |
1280 | int idx; |
1281 | |
1282 | DEBUG_LOCKS_WARN_ON(!irqs_disabled()); |
1283 | |
1284 | class = look_up_lock_class(lock, subclass); |
1285 | if (likely(class)) |
1286 | goto out_set_class_cache; |
1287 | |
1288 | if (!lock->key) { |
1289 | if (!assign_lock_key(lock)) |
1290 | return NULL; |
1291 | } else if (!static_obj(obj: lock->key) && !is_dynamic_key(key: lock->key)) { |
1292 | return NULL; |
1293 | } |
1294 | |
1295 | key = lock->key->subkeys + subclass; |
1296 | hash_head = classhashentry(key); |
1297 | |
1298 | if (!graph_lock()) { |
1299 | return NULL; |
1300 | } |
1301 | /* |
1302 | * We have to do the hash-walk again, to avoid races |
1303 | * with another CPU: |
1304 | */ |
1305 | hlist_for_each_entry_rcu(class, hash_head, hash_entry) { |
1306 | if (class->key == key) |
1307 | goto out_unlock_set; |
1308 | } |
1309 | |
1310 | init_data_structures_once(); |
1311 | |
1312 | /* Allocate a new lock class and add it to the hash. */ |
1313 | class = list_first_entry_or_null(&free_lock_classes, typeof(*class), |
1314 | lock_entry); |
1315 | if (!class) { |
1316 | if (!debug_locks_off_graph_unlock()) { |
1317 | return NULL; |
1318 | } |
1319 | |
1320 | print_lockdep_off(bug_msg: "BUG: MAX_LOCKDEP_KEYS too low!" ); |
1321 | dump_stack(); |
1322 | return NULL; |
1323 | } |
1324 | nr_lock_classes++; |
1325 | __set_bit(class - lock_classes, lock_classes_in_use); |
1326 | debug_atomic_inc(nr_unused_locks); |
1327 | class->key = key; |
1328 | class->name = lock->name; |
1329 | class->subclass = subclass; |
1330 | WARN_ON_ONCE(!list_empty(&class->locks_before)); |
1331 | WARN_ON_ONCE(!list_empty(&class->locks_after)); |
1332 | class->name_version = count_matching_names(new_class: class); |
1333 | class->wait_type_inner = lock->wait_type_inner; |
1334 | class->wait_type_outer = lock->wait_type_outer; |
1335 | class->lock_type = lock->lock_type; |
1336 | /* |
1337 | * We use RCU's safe list-add method to make |
1338 | * parallel walking of the hash-list safe: |
1339 | */ |
1340 | hlist_add_head_rcu(n: &class->hash_entry, h: hash_head); |
1341 | /* |
1342 | * Remove the class from the free list and add it to the global list |
1343 | * of classes. |
1344 | */ |
1345 | list_move_tail(list: &class->lock_entry, head: &all_lock_classes); |
1346 | idx = class - lock_classes; |
1347 | if (idx > max_lock_class_idx) |
1348 | max_lock_class_idx = idx; |
1349 | |
1350 | if (verbose(class)) { |
1351 | graph_unlock(); |
1352 | |
1353 | printk("\nnew class %px: %s" , class->key, class->name); |
1354 | if (class->name_version > 1) |
1355 | printk(KERN_CONT "#%d" , class->name_version); |
1356 | printk(KERN_CONT "\n" ); |
1357 | dump_stack(); |
1358 | |
1359 | if (!graph_lock()) { |
1360 | return NULL; |
1361 | } |
1362 | } |
1363 | out_unlock_set: |
1364 | graph_unlock(); |
1365 | |
1366 | out_set_class_cache: |
1367 | if (!subclass || force) |
1368 | lock->class_cache[0] = class; |
1369 | else if (subclass < NR_LOCKDEP_CACHING_CLASSES) |
1370 | lock->class_cache[subclass] = class; |
1371 | |
1372 | /* |
1373 | * Hash collision, did we smoke some? We found a class with a matching |
1374 | * hash but the subclass -- which is hashed in -- didn't match. |
1375 | */ |
1376 | if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass)) |
1377 | return NULL; |
1378 | |
1379 | return class; |
1380 | } |
1381 | |
1382 | #ifdef CONFIG_PROVE_LOCKING |
1383 | /* |
1384 | * Allocate a lockdep entry. (assumes the graph_lock held, returns |
1385 | * with NULL on failure) |
1386 | */ |
1387 | static struct lock_list *alloc_list_entry(void) |
1388 | { |
1389 | int idx = find_first_zero_bit(addr: list_entries_in_use, |
1390 | ARRAY_SIZE(list_entries)); |
1391 | |
1392 | if (idx >= ARRAY_SIZE(list_entries)) { |
1393 | if (!debug_locks_off_graph_unlock()) |
1394 | return NULL; |
1395 | |
1396 | print_lockdep_off(bug_msg: "BUG: MAX_LOCKDEP_ENTRIES too low!" ); |
1397 | dump_stack(); |
1398 | return NULL; |
1399 | } |
1400 | nr_list_entries++; |
1401 | __set_bit(idx, list_entries_in_use); |
1402 | return list_entries + idx; |
1403 | } |
1404 | |
1405 | /* |
1406 | * Add a new dependency to the head of the list: |
1407 | */ |
1408 | static int add_lock_to_list(struct lock_class *this, |
1409 | struct lock_class *links_to, struct list_head *head, |
1410 | u16 distance, u8 dep, |
1411 | const struct lock_trace *trace) |
1412 | { |
1413 | struct lock_list *entry; |
1414 | /* |
1415 | * Lock not present yet - get a new dependency struct and |
1416 | * add it to the list: |
1417 | */ |
1418 | entry = alloc_list_entry(); |
1419 | if (!entry) |
1420 | return 0; |
1421 | |
1422 | entry->class = this; |
1423 | entry->links_to = links_to; |
1424 | entry->dep = dep; |
1425 | entry->distance = distance; |
1426 | entry->trace = trace; |
1427 | /* |
1428 | * Both allocation and removal are done under the graph lock; but |
1429 | * iteration is under RCU-sched; see look_up_lock_class() and |
1430 | * lockdep_free_key_range(). |
1431 | */ |
1432 | list_add_tail_rcu(new: &entry->entry, head); |
1433 | |
1434 | return 1; |
1435 | } |
1436 | |
1437 | /* |
1438 | * For good efficiency of modular, we use power of 2 |
1439 | */ |
1440 | #define MAX_CIRCULAR_QUEUE_SIZE (1UL << CONFIG_LOCKDEP_CIRCULAR_QUEUE_BITS) |
1441 | #define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1) |
1442 | |
1443 | /* |
1444 | * The circular_queue and helpers are used to implement graph |
1445 | * breadth-first search (BFS) algorithm, by which we can determine |
1446 | * whether there is a path from a lock to another. In deadlock checks, |
1447 | * a path from the next lock to be acquired to a previous held lock |
1448 | * indicates that adding the <prev> -> <next> lock dependency will |
1449 | * produce a circle in the graph. Breadth-first search instead of |
1450 | * depth-first search is used in order to find the shortest (circular) |
1451 | * path. |
1452 | */ |
1453 | struct circular_queue { |
1454 | struct lock_list *element[MAX_CIRCULAR_QUEUE_SIZE]; |
1455 | unsigned int front, rear; |
1456 | }; |
1457 | |
1458 | static struct circular_queue lock_cq; |
1459 | |
1460 | unsigned int max_bfs_queue_depth; |
1461 | |
1462 | static unsigned int lockdep_dependency_gen_id; |
1463 | |
1464 | static inline void __cq_init(struct circular_queue *cq) |
1465 | { |
1466 | cq->front = cq->rear = 0; |
1467 | lockdep_dependency_gen_id++; |
1468 | } |
1469 | |
1470 | static inline int __cq_empty(struct circular_queue *cq) |
1471 | { |
1472 | return (cq->front == cq->rear); |
1473 | } |
1474 | |
1475 | static inline int __cq_full(struct circular_queue *cq) |
1476 | { |
1477 | return ((cq->rear + 1) & CQ_MASK) == cq->front; |
1478 | } |
1479 | |
1480 | static inline int __cq_enqueue(struct circular_queue *cq, struct lock_list *elem) |
1481 | { |
1482 | if (__cq_full(cq)) |
1483 | return -1; |
1484 | |
1485 | cq->element[cq->rear] = elem; |
1486 | cq->rear = (cq->rear + 1) & CQ_MASK; |
1487 | return 0; |
1488 | } |
1489 | |
1490 | /* |
1491 | * Dequeue an element from the circular_queue, return a lock_list if |
1492 | * the queue is not empty, or NULL if otherwise. |
1493 | */ |
1494 | static inline struct lock_list * __cq_dequeue(struct circular_queue *cq) |
1495 | { |
1496 | struct lock_list * lock; |
1497 | |
1498 | if (__cq_empty(cq)) |
1499 | return NULL; |
1500 | |
1501 | lock = cq->element[cq->front]; |
1502 | cq->front = (cq->front + 1) & CQ_MASK; |
1503 | |
1504 | return lock; |
1505 | } |
1506 | |
1507 | static inline unsigned int __cq_get_elem_count(struct circular_queue *cq) |
1508 | { |
1509 | return (cq->rear - cq->front) & CQ_MASK; |
1510 | } |
1511 | |
1512 | static inline void mark_lock_accessed(struct lock_list *lock) |
1513 | { |
1514 | lock->class->dep_gen_id = lockdep_dependency_gen_id; |
1515 | } |
1516 | |
1517 | static inline void visit_lock_entry(struct lock_list *lock, |
1518 | struct lock_list *parent) |
1519 | { |
1520 | lock->parent = parent; |
1521 | } |
1522 | |
1523 | static inline unsigned long lock_accessed(struct lock_list *lock) |
1524 | { |
1525 | return lock->class->dep_gen_id == lockdep_dependency_gen_id; |
1526 | } |
1527 | |
1528 | static inline struct lock_list *get_lock_parent(struct lock_list *child) |
1529 | { |
1530 | return child->parent; |
1531 | } |
1532 | |
1533 | static inline int get_lock_depth(struct lock_list *child) |
1534 | { |
1535 | int depth = 0; |
1536 | struct lock_list *parent; |
1537 | |
1538 | while ((parent = get_lock_parent(child))) { |
1539 | child = parent; |
1540 | depth++; |
1541 | } |
1542 | return depth; |
1543 | } |
1544 | |
1545 | /* |
1546 | * Return the forward or backward dependency list. |
1547 | * |
1548 | * @lock: the lock_list to get its class's dependency list |
1549 | * @offset: the offset to struct lock_class to determine whether it is |
1550 | * locks_after or locks_before |
1551 | */ |
1552 | static inline struct list_head *get_dep_list(struct lock_list *lock, int offset) |
1553 | { |
1554 | void *lock_class = lock->class; |
1555 | |
1556 | return lock_class + offset; |
1557 | } |
1558 | /* |
1559 | * Return values of a bfs search: |
1560 | * |
1561 | * BFS_E* indicates an error |
1562 | * BFS_R* indicates a result (match or not) |
1563 | * |
1564 | * BFS_EINVALIDNODE: Find a invalid node in the graph. |
1565 | * |
1566 | * BFS_EQUEUEFULL: The queue is full while doing the bfs. |
1567 | * |
1568 | * BFS_RMATCH: Find the matched node in the graph, and put that node into |
1569 | * *@target_entry. |
1570 | * |
1571 | * BFS_RNOMATCH: Haven't found the matched node and keep *@target_entry |
1572 | * _unchanged_. |
1573 | */ |
1574 | enum bfs_result { |
1575 | BFS_EINVALIDNODE = -2, |
1576 | BFS_EQUEUEFULL = -1, |
1577 | BFS_RMATCH = 0, |
1578 | BFS_RNOMATCH = 1, |
1579 | }; |
1580 | |
1581 | /* |
1582 | * bfs_result < 0 means error |
1583 | */ |
1584 | static inline bool bfs_error(enum bfs_result res) |
1585 | { |
1586 | return res < 0; |
1587 | } |
1588 | |
1589 | /* |
1590 | * DEP_*_BIT in lock_list::dep |
1591 | * |
1592 | * For dependency @prev -> @next: |
1593 | * |
1594 | * SR: @prev is shared reader (->read != 0) and @next is recursive reader |
1595 | * (->read == 2) |
1596 | * ER: @prev is exclusive locker (->read == 0) and @next is recursive reader |
1597 | * SN: @prev is shared reader and @next is non-recursive locker (->read != 2) |
1598 | * EN: @prev is exclusive locker and @next is non-recursive locker |
1599 | * |
1600 | * Note that we define the value of DEP_*_BITs so that: |
1601 | * bit0 is prev->read == 0 |
1602 | * bit1 is next->read != 2 |
1603 | */ |
1604 | #define DEP_SR_BIT (0 + (0 << 1)) /* 0 */ |
1605 | #define DEP_ER_BIT (1 + (0 << 1)) /* 1 */ |
1606 | #define DEP_SN_BIT (0 + (1 << 1)) /* 2 */ |
1607 | #define DEP_EN_BIT (1 + (1 << 1)) /* 3 */ |
1608 | |
1609 | #define DEP_SR_MASK (1U << (DEP_SR_BIT)) |
1610 | #define DEP_ER_MASK (1U << (DEP_ER_BIT)) |
1611 | #define DEP_SN_MASK (1U << (DEP_SN_BIT)) |
1612 | #define DEP_EN_MASK (1U << (DEP_EN_BIT)) |
1613 | |
1614 | static inline unsigned int |
1615 | __calc_dep_bit(struct held_lock *prev, struct held_lock *next) |
1616 | { |
1617 | return (prev->read == 0) + ((next->read != 2) << 1); |
1618 | } |
1619 | |
1620 | static inline u8 calc_dep(struct held_lock *prev, struct held_lock *next) |
1621 | { |
1622 | return 1U << __calc_dep_bit(prev, next); |
1623 | } |
1624 | |
1625 | /* |
1626 | * calculate the dep_bit for backwards edges. We care about whether @prev is |
1627 | * shared and whether @next is recursive. |
1628 | */ |
1629 | static inline unsigned int |
1630 | __calc_dep_bitb(struct held_lock *prev, struct held_lock *next) |
1631 | { |
1632 | return (next->read != 2) + ((prev->read == 0) << 1); |
1633 | } |
1634 | |
1635 | static inline u8 calc_depb(struct held_lock *prev, struct held_lock *next) |
1636 | { |
1637 | return 1U << __calc_dep_bitb(prev, next); |
1638 | } |
1639 | |
1640 | /* |
1641 | * Initialize a lock_list entry @lock belonging to @class as the root for a BFS |
1642 | * search. |
1643 | */ |
1644 | static inline void __bfs_init_root(struct lock_list *lock, |
1645 | struct lock_class *class) |
1646 | { |
1647 | lock->class = class; |
1648 | lock->parent = NULL; |
1649 | lock->only_xr = 0; |
1650 | } |
1651 | |
1652 | /* |
1653 | * Initialize a lock_list entry @lock based on a lock acquisition @hlock as the |
1654 | * root for a BFS search. |
1655 | * |
1656 | * ->only_xr of the initial lock node is set to @hlock->read == 2, to make sure |
1657 | * that <prev> -> @hlock and @hlock -> <whatever __bfs() found> is not -(*R)-> |
1658 | * and -(S*)->. |
1659 | */ |
1660 | static inline void bfs_init_root(struct lock_list *lock, |
1661 | struct held_lock *hlock) |
1662 | { |
1663 | __bfs_init_root(lock, class: hlock_class(hlock)); |
1664 | lock->only_xr = (hlock->read == 2); |
1665 | } |
1666 | |
1667 | /* |
1668 | * Similar to bfs_init_root() but initialize the root for backwards BFS. |
1669 | * |
1670 | * ->only_xr of the initial lock node is set to @hlock->read != 0, to make sure |
1671 | * that <next> -> @hlock and @hlock -> <whatever backwards BFS found> is not |
1672 | * -(*S)-> and -(R*)-> (reverse order of -(*R)-> and -(S*)->). |
1673 | */ |
1674 | static inline void bfs_init_rootb(struct lock_list *lock, |
1675 | struct held_lock *hlock) |
1676 | { |
1677 | __bfs_init_root(lock, class: hlock_class(hlock)); |
1678 | lock->only_xr = (hlock->read != 0); |
1679 | } |
1680 | |
1681 | static inline struct lock_list *__bfs_next(struct lock_list *lock, int offset) |
1682 | { |
1683 | if (!lock || !lock->parent) |
1684 | return NULL; |
1685 | |
1686 | return list_next_or_null_rcu(get_dep_list(lock->parent, offset), |
1687 | &lock->entry, struct lock_list, entry); |
1688 | } |
1689 | |
1690 | /* |
1691 | * Breadth-First Search to find a strong path in the dependency graph. |
1692 | * |
1693 | * @source_entry: the source of the path we are searching for. |
1694 | * @data: data used for the second parameter of @match function |
1695 | * @match: match function for the search |
1696 | * @target_entry: pointer to the target of a matched path |
1697 | * @offset: the offset to struct lock_class to determine whether it is |
1698 | * locks_after or locks_before |
1699 | * |
1700 | * We may have multiple edges (considering different kinds of dependencies, |
1701 | * e.g. ER and SN) between two nodes in the dependency graph. But |
1702 | * only the strong dependency path in the graph is relevant to deadlocks. A |
1703 | * strong dependency path is a dependency path that doesn't have two adjacent |
1704 | * dependencies as -(*R)-> -(S*)->, please see: |
1705 | * |
1706 | * Documentation/locking/lockdep-design.rst |
1707 | * |
1708 | * for more explanation of the definition of strong dependency paths |
1709 | * |
1710 | * In __bfs(), we only traverse in the strong dependency path: |
1711 | * |
1712 | * In lock_list::only_xr, we record whether the previous dependency only |
1713 | * has -(*R)-> in the search, and if it does (prev only has -(*R)->), we |
1714 | * filter out any -(S*)-> in the current dependency and after that, the |
1715 | * ->only_xr is set according to whether we only have -(*R)-> left. |
1716 | */ |
1717 | static enum bfs_result __bfs(struct lock_list *source_entry, |
1718 | void *data, |
1719 | bool (*match)(struct lock_list *entry, void *data), |
1720 | bool (*skip)(struct lock_list *entry, void *data), |
1721 | struct lock_list **target_entry, |
1722 | int offset) |
1723 | { |
1724 | struct circular_queue *cq = &lock_cq; |
1725 | struct lock_list *lock = NULL; |
1726 | struct lock_list *entry; |
1727 | struct list_head *head; |
1728 | unsigned int cq_depth; |
1729 | bool first; |
1730 | |
1731 | lockdep_assert_locked(); |
1732 | |
1733 | __cq_init(cq); |
1734 | __cq_enqueue(cq, elem: source_entry); |
1735 | |
1736 | while ((lock = __bfs_next(lock, offset)) || (lock = __cq_dequeue(cq))) { |
1737 | if (!lock->class) |
1738 | return BFS_EINVALIDNODE; |
1739 | |
1740 | /* |
1741 | * Step 1: check whether we already finish on this one. |
1742 | * |
1743 | * If we have visited all the dependencies from this @lock to |
1744 | * others (iow, if we have visited all lock_list entries in |
1745 | * @lock->class->locks_{after,before}) we skip, otherwise go |
1746 | * and visit all the dependencies in the list and mark this |
1747 | * list accessed. |
1748 | */ |
1749 | if (lock_accessed(lock)) |
1750 | continue; |
1751 | else |
1752 | mark_lock_accessed(lock); |
1753 | |
1754 | /* |
1755 | * Step 2: check whether prev dependency and this form a strong |
1756 | * dependency path. |
1757 | */ |
1758 | if (lock->parent) { /* Parent exists, check prev dependency */ |
1759 | u8 dep = lock->dep; |
1760 | bool prev_only_xr = lock->parent->only_xr; |
1761 | |
1762 | /* |
1763 | * Mask out all -(S*)-> if we only have *R in previous |
1764 | * step, because -(*R)-> -(S*)-> don't make up a strong |
1765 | * dependency. |
1766 | */ |
1767 | if (prev_only_xr) |
1768 | dep &= ~(DEP_SR_MASK | DEP_SN_MASK); |
1769 | |
1770 | /* If nothing left, we skip */ |
1771 | if (!dep) |
1772 | continue; |
1773 | |
1774 | /* If there are only -(*R)-> left, set that for the next step */ |
1775 | lock->only_xr = !(dep & (DEP_SN_MASK | DEP_EN_MASK)); |
1776 | } |
1777 | |
1778 | /* |
1779 | * Step 3: we haven't visited this and there is a strong |
1780 | * dependency path to this, so check with @match. |
1781 | * If @skip is provide and returns true, we skip this |
1782 | * lock (and any path this lock is in). |
1783 | */ |
1784 | if (skip && skip(lock, data)) |
1785 | continue; |
1786 | |
1787 | if (match(lock, data)) { |
1788 | *target_entry = lock; |
1789 | return BFS_RMATCH; |
1790 | } |
1791 | |
1792 | /* |
1793 | * Step 4: if not match, expand the path by adding the |
1794 | * forward or backwards dependencies in the search |
1795 | * |
1796 | */ |
1797 | first = true; |
1798 | head = get_dep_list(lock, offset); |
1799 | list_for_each_entry_rcu(entry, head, entry) { |
1800 | visit_lock_entry(lock: entry, parent: lock); |
1801 | |
1802 | /* |
1803 | * Note we only enqueue the first of the list into the |
1804 | * queue, because we can always find a sibling |
1805 | * dependency from one (see __bfs_next()), as a result |
1806 | * the space of queue is saved. |
1807 | */ |
1808 | if (!first) |
1809 | continue; |
1810 | |
1811 | first = false; |
1812 | |
1813 | if (__cq_enqueue(cq, elem: entry)) |
1814 | return BFS_EQUEUEFULL; |
1815 | |
1816 | cq_depth = __cq_get_elem_count(cq); |
1817 | if (max_bfs_queue_depth < cq_depth) |
1818 | max_bfs_queue_depth = cq_depth; |
1819 | } |
1820 | } |
1821 | |
1822 | return BFS_RNOMATCH; |
1823 | } |
1824 | |
1825 | static inline enum bfs_result |
1826 | __bfs_forwards(struct lock_list *src_entry, |
1827 | void *data, |
1828 | bool (*match)(struct lock_list *entry, void *data), |
1829 | bool (*skip)(struct lock_list *entry, void *data), |
1830 | struct lock_list **target_entry) |
1831 | { |
1832 | return __bfs(source_entry: src_entry, data, match, skip, target_entry, |
1833 | offsetof(struct lock_class, locks_after)); |
1834 | |
1835 | } |
1836 | |
1837 | static inline enum bfs_result |
1838 | __bfs_backwards(struct lock_list *src_entry, |
1839 | void *data, |
1840 | bool (*match)(struct lock_list *entry, void *data), |
1841 | bool (*skip)(struct lock_list *entry, void *data), |
1842 | struct lock_list **target_entry) |
1843 | { |
1844 | return __bfs(source_entry: src_entry, data, match, skip, target_entry, |
1845 | offsetof(struct lock_class, locks_before)); |
1846 | |
1847 | } |
1848 | |
1849 | static void print_lock_trace(const struct lock_trace *trace, |
1850 | unsigned int spaces) |
1851 | { |
1852 | stack_trace_print(trace: trace->entries, nr_entries: trace->nr_entries, spaces); |
1853 | } |
1854 | |
1855 | /* |
1856 | * Print a dependency chain entry (this is only done when a deadlock |
1857 | * has been detected): |
1858 | */ |
1859 | static noinline void |
1860 | print_circular_bug_entry(struct lock_list *target, int depth) |
1861 | { |
1862 | if (debug_locks_silent) |
1863 | return; |
1864 | printk("\n-> #%u" , depth); |
1865 | print_lock_name(NULL, class: target->class); |
1866 | printk(KERN_CONT ":\n" ); |
1867 | print_lock_trace(trace: target->trace, spaces: 6); |
1868 | } |
1869 | |
1870 | static void |
1871 | print_circular_lock_scenario(struct held_lock *src, |
1872 | struct held_lock *tgt, |
1873 | struct lock_list *prt) |
1874 | { |
1875 | struct lock_class *source = hlock_class(hlock: src); |
1876 | struct lock_class *target = hlock_class(hlock: tgt); |
1877 | struct lock_class *parent = prt->class; |
1878 | int src_read = src->read; |
1879 | int tgt_read = tgt->read; |
1880 | |
1881 | /* |
1882 | * A direct locking problem where unsafe_class lock is taken |
1883 | * directly by safe_class lock, then all we need to show |
1884 | * is the deadlock scenario, as it is obvious that the |
1885 | * unsafe lock is taken under the safe lock. |
1886 | * |
1887 | * But if there is a chain instead, where the safe lock takes |
1888 | * an intermediate lock (middle_class) where this lock is |
1889 | * not the same as the safe lock, then the lock chain is |
1890 | * used to describe the problem. Otherwise we would need |
1891 | * to show a different CPU case for each link in the chain |
1892 | * from the safe_class lock to the unsafe_class lock. |
1893 | */ |
1894 | if (parent != source) { |
1895 | printk("Chain exists of:\n " ); |
1896 | __print_lock_name(hlock: src, class: source); |
1897 | printk(KERN_CONT " --> " ); |
1898 | __print_lock_name(NULL, class: parent); |
1899 | printk(KERN_CONT " --> " ); |
1900 | __print_lock_name(hlock: tgt, class: target); |
1901 | printk(KERN_CONT "\n\n" ); |
1902 | } |
1903 | |
1904 | printk(" Possible unsafe locking scenario:\n\n" ); |
1905 | printk(" CPU0 CPU1\n" ); |
1906 | printk(" ---- ----\n" ); |
1907 | if (tgt_read != 0) |
1908 | printk(" rlock(" ); |
1909 | else |
1910 | printk(" lock(" ); |
1911 | __print_lock_name(hlock: tgt, class: target); |
1912 | printk(KERN_CONT ");\n" ); |
1913 | printk(" lock(" ); |
1914 | __print_lock_name(NULL, class: parent); |
1915 | printk(KERN_CONT ");\n" ); |
1916 | printk(" lock(" ); |
1917 | __print_lock_name(hlock: tgt, class: target); |
1918 | printk(KERN_CONT ");\n" ); |
1919 | if (src_read != 0) |
1920 | printk(" rlock(" ); |
1921 | else if (src->sync) |
1922 | printk(" sync(" ); |
1923 | else |
1924 | printk(" lock(" ); |
1925 | __print_lock_name(hlock: src, class: source); |
1926 | printk(KERN_CONT ");\n" ); |
1927 | printk("\n *** DEADLOCK ***\n\n" ); |
1928 | } |
1929 | |
1930 | /* |
1931 | * When a circular dependency is detected, print the |
1932 | * header first: |
1933 | */ |
1934 | static noinline void |
1935 | (struct lock_list *entry, unsigned int depth, |
1936 | struct held_lock *check_src, |
1937 | struct held_lock *check_tgt) |
1938 | { |
1939 | struct task_struct *curr = current; |
1940 | |
1941 | if (debug_locks_silent) |
1942 | return; |
1943 | |
1944 | pr_warn("\n" ); |
1945 | pr_warn("======================================================\n" ); |
1946 | pr_warn("WARNING: possible circular locking dependency detected\n" ); |
1947 | print_kernel_ident(); |
1948 | pr_warn("------------------------------------------------------\n" ); |
1949 | pr_warn("%s/%d is trying to acquire lock:\n" , |
1950 | curr->comm, task_pid_nr(curr)); |
1951 | print_lock(hlock: check_src); |
1952 | |
1953 | pr_warn("\nbut task is already holding lock:\n" ); |
1954 | |
1955 | print_lock(hlock: check_tgt); |
1956 | pr_warn("\nwhich lock already depends on the new lock.\n\n" ); |
1957 | pr_warn("\nthe existing dependency chain (in reverse order) is:\n" ); |
1958 | |
1959 | print_circular_bug_entry(target: entry, depth); |
1960 | } |
1961 | |
1962 | /* |
1963 | * We are about to add A -> B into the dependency graph, and in __bfs() a |
1964 | * strong dependency path A -> .. -> B is found: hlock_class equals |
1965 | * entry->class. |
1966 | * |
1967 | * If A -> .. -> B can replace A -> B in any __bfs() search (means the former |
1968 | * is _stronger_ than or equal to the latter), we consider A -> B as redundant. |
1969 | * For example if A -> .. -> B is -(EN)-> (i.e. A -(E*)-> .. -(*N)-> B), and A |
1970 | * -> B is -(ER)-> or -(EN)->, then we don't need to add A -> B into the |
1971 | * dependency graph, as any strong path ..-> A -> B ->.. we can get with |
1972 | * having dependency A -> B, we could already get a equivalent path ..-> A -> |
1973 | * .. -> B -> .. with A -> .. -> B. Therefore A -> B is redundant. |
1974 | * |
1975 | * We need to make sure both the start and the end of A -> .. -> B is not |
1976 | * weaker than A -> B. For the start part, please see the comment in |
1977 | * check_redundant(). For the end part, we need: |
1978 | * |
1979 | * Either |
1980 | * |
1981 | * a) A -> B is -(*R)-> (everything is not weaker than that) |
1982 | * |
1983 | * or |
1984 | * |
1985 | * b) A -> .. -> B is -(*N)-> (nothing is stronger than this) |
1986 | * |
1987 | */ |
1988 | static inline bool hlock_equal(struct lock_list *entry, void *data) |
1989 | { |
1990 | struct held_lock *hlock = (struct held_lock *)data; |
1991 | |
1992 | return hlock_class(hlock) == entry->class && /* Found A -> .. -> B */ |
1993 | (hlock->read == 2 || /* A -> B is -(*R)-> */ |
1994 | !entry->only_xr); /* A -> .. -> B is -(*N)-> */ |
1995 | } |
1996 | |
1997 | /* |
1998 | * We are about to add B -> A into the dependency graph, and in __bfs() a |
1999 | * strong dependency path A -> .. -> B is found: hlock_class equals |
2000 | * entry->class. |
2001 | * |
2002 | * We will have a deadlock case (conflict) if A -> .. -> B -> A is a strong |
2003 | * dependency cycle, that means: |
2004 | * |
2005 | * Either |
2006 | * |
2007 | * a) B -> A is -(E*)-> |
2008 | * |
2009 | * or |
2010 | * |
2011 | * b) A -> .. -> B is -(*N)-> (i.e. A -> .. -(*N)-> B) |
2012 | * |
2013 | * as then we don't have -(*R)-> -(S*)-> in the cycle. |
2014 | */ |
2015 | static inline bool hlock_conflict(struct lock_list *entry, void *data) |
2016 | { |
2017 | struct held_lock *hlock = (struct held_lock *)data; |
2018 | |
2019 | return hlock_class(hlock) == entry->class && /* Found A -> .. -> B */ |
2020 | (hlock->read == 0 || /* B -> A is -(E*)-> */ |
2021 | !entry->only_xr); /* A -> .. -> B is -(*N)-> */ |
2022 | } |
2023 | |
2024 | static noinline void print_circular_bug(struct lock_list *this, |
2025 | struct lock_list *target, |
2026 | struct held_lock *check_src, |
2027 | struct held_lock *check_tgt) |
2028 | { |
2029 | struct task_struct *curr = current; |
2030 | struct lock_list *parent; |
2031 | struct lock_list *first_parent; |
2032 | int depth; |
2033 | |
2034 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) |
2035 | return; |
2036 | |
2037 | this->trace = save_trace(); |
2038 | if (!this->trace) |
2039 | return; |
2040 | |
2041 | depth = get_lock_depth(child: target); |
2042 | |
2043 | print_circular_bug_header(entry: target, depth, check_src, check_tgt); |
2044 | |
2045 | parent = get_lock_parent(child: target); |
2046 | first_parent = parent; |
2047 | |
2048 | while (parent) { |
2049 | print_circular_bug_entry(target: parent, depth: --depth); |
2050 | parent = get_lock_parent(child: parent); |
2051 | } |
2052 | |
2053 | printk("\nother info that might help us debug this:\n\n" ); |
2054 | print_circular_lock_scenario(src: check_src, tgt: check_tgt, |
2055 | prt: first_parent); |
2056 | |
2057 | lockdep_print_held_locks(p: curr); |
2058 | |
2059 | printk("\nstack backtrace:\n" ); |
2060 | dump_stack(); |
2061 | } |
2062 | |
2063 | static noinline void print_bfs_bug(int ret) |
2064 | { |
2065 | if (!debug_locks_off_graph_unlock()) |
2066 | return; |
2067 | |
2068 | /* |
2069 | * Breadth-first-search failed, graph got corrupted? |
2070 | */ |
2071 | WARN(1, "lockdep bfs error:%d\n" , ret); |
2072 | } |
2073 | |
2074 | static bool noop_count(struct lock_list *entry, void *data) |
2075 | { |
2076 | (*(unsigned long *)data)++; |
2077 | return false; |
2078 | } |
2079 | |
2080 | static unsigned long __lockdep_count_forward_deps(struct lock_list *this) |
2081 | { |
2082 | unsigned long count = 0; |
2083 | struct lock_list *target_entry; |
2084 | |
2085 | __bfs_forwards(src_entry: this, data: (void *)&count, match: noop_count, NULL, target_entry: &target_entry); |
2086 | |
2087 | return count; |
2088 | } |
2089 | unsigned long lockdep_count_forward_deps(struct lock_class *class) |
2090 | { |
2091 | unsigned long ret, flags; |
2092 | struct lock_list this; |
2093 | |
2094 | __bfs_init_root(lock: &this, class); |
2095 | |
2096 | raw_local_irq_save(flags); |
2097 | lockdep_lock(); |
2098 | ret = __lockdep_count_forward_deps(this: &this); |
2099 | lockdep_unlock(); |
2100 | raw_local_irq_restore(flags); |
2101 | |
2102 | return ret; |
2103 | } |
2104 | |
2105 | static unsigned long __lockdep_count_backward_deps(struct lock_list *this) |
2106 | { |
2107 | unsigned long count = 0; |
2108 | struct lock_list *target_entry; |
2109 | |
2110 | __bfs_backwards(src_entry: this, data: (void *)&count, match: noop_count, NULL, target_entry: &target_entry); |
2111 | |
2112 | return count; |
2113 | } |
2114 | |
2115 | unsigned long lockdep_count_backward_deps(struct lock_class *class) |
2116 | { |
2117 | unsigned long ret, flags; |
2118 | struct lock_list this; |
2119 | |
2120 | __bfs_init_root(lock: &this, class); |
2121 | |
2122 | raw_local_irq_save(flags); |
2123 | lockdep_lock(); |
2124 | ret = __lockdep_count_backward_deps(this: &this); |
2125 | lockdep_unlock(); |
2126 | raw_local_irq_restore(flags); |
2127 | |
2128 | return ret; |
2129 | } |
2130 | |
2131 | /* |
2132 | * Check that the dependency graph starting at <src> can lead to |
2133 | * <target> or not. |
2134 | */ |
2135 | static noinline enum bfs_result |
2136 | check_path(struct held_lock *target, struct lock_list *src_entry, |
2137 | bool (*match)(struct lock_list *entry, void *data), |
2138 | bool (*skip)(struct lock_list *entry, void *data), |
2139 | struct lock_list **target_entry) |
2140 | { |
2141 | enum bfs_result ret; |
2142 | |
2143 | ret = __bfs_forwards(src_entry, data: target, match, skip, target_entry); |
2144 | |
2145 | if (unlikely(bfs_error(ret))) |
2146 | print_bfs_bug(ret); |
2147 | |
2148 | return ret; |
2149 | } |
2150 | |
2151 | static void print_deadlock_bug(struct task_struct *, struct held_lock *, struct held_lock *); |
2152 | |
2153 | /* |
2154 | * Prove that the dependency graph starting at <src> can not |
2155 | * lead to <target>. If it can, there is a circle when adding |
2156 | * <target> -> <src> dependency. |
2157 | * |
2158 | * Print an error and return BFS_RMATCH if it does. |
2159 | */ |
2160 | static noinline enum bfs_result |
2161 | check_noncircular(struct held_lock *src, struct held_lock *target, |
2162 | struct lock_trace **const trace) |
2163 | { |
2164 | enum bfs_result ret; |
2165 | struct lock_list *target_entry; |
2166 | struct lock_list src_entry; |
2167 | |
2168 | bfs_init_root(lock: &src_entry, hlock: src); |
2169 | |
2170 | debug_atomic_inc(nr_cyclic_checks); |
2171 | |
2172 | ret = check_path(target, src_entry: &src_entry, match: hlock_conflict, NULL, target_entry: &target_entry); |
2173 | |
2174 | if (unlikely(ret == BFS_RMATCH)) { |
2175 | if (!*trace) { |
2176 | /* |
2177 | * If save_trace fails here, the printing might |
2178 | * trigger a WARN but because of the !nr_entries it |
2179 | * should not do bad things. |
2180 | */ |
2181 | *trace = save_trace(); |
2182 | } |
2183 | |
2184 | if (src->class_idx == target->class_idx) |
2185 | print_deadlock_bug(current, src, target); |
2186 | else |
2187 | print_circular_bug(this: &src_entry, target: target_entry, check_src: src, check_tgt: target); |
2188 | } |
2189 | |
2190 | return ret; |
2191 | } |
2192 | |
2193 | #ifdef CONFIG_TRACE_IRQFLAGS |
2194 | |
2195 | /* |
2196 | * Forwards and backwards subgraph searching, for the purposes of |
2197 | * proving that two subgraphs can be connected by a new dependency |
2198 | * without creating any illegal irq-safe -> irq-unsafe lock dependency. |
2199 | * |
2200 | * A irq safe->unsafe deadlock happens with the following conditions: |
2201 | * |
2202 | * 1) We have a strong dependency path A -> ... -> B |
2203 | * |
2204 | * 2) and we have ENABLED_IRQ usage of B and USED_IN_IRQ usage of A, therefore |
2205 | * irq can create a new dependency B -> A (consider the case that a holder |
2206 | * of B gets interrupted by an irq whose handler will try to acquire A). |
2207 | * |
2208 | * 3) the dependency circle A -> ... -> B -> A we get from 1) and 2) is a |
2209 | * strong circle: |
2210 | * |
2211 | * For the usage bits of B: |
2212 | * a) if A -> B is -(*N)->, then B -> A could be any type, so any |
2213 | * ENABLED_IRQ usage suffices. |
2214 | * b) if A -> B is -(*R)->, then B -> A must be -(E*)->, so only |
2215 | * ENABLED_IRQ_*_READ usage suffices. |
2216 | * |
2217 | * For the usage bits of A: |
2218 | * c) if A -> B is -(E*)->, then B -> A could be any type, so any |
2219 | * USED_IN_IRQ usage suffices. |
2220 | * d) if A -> B is -(S*)->, then B -> A must be -(*N)->, so only |
2221 | * USED_IN_IRQ_*_READ usage suffices. |
2222 | */ |
2223 | |
2224 | /* |
2225 | * There is a strong dependency path in the dependency graph: A -> B, and now |
2226 | * we need to decide which usage bit of A should be accumulated to detect |
2227 | * safe->unsafe bugs. |
2228 | * |
2229 | * Note that usage_accumulate() is used in backwards search, so ->only_xr |
2230 | * stands for whether A -> B only has -(S*)-> (in this case ->only_xr is true). |
2231 | * |
2232 | * As above, if only_xr is false, which means A -> B has -(E*)-> dependency |
2233 | * path, any usage of A should be considered. Otherwise, we should only |
2234 | * consider _READ usage. |
2235 | */ |
2236 | static inline bool usage_accumulate(struct lock_list *entry, void *mask) |
2237 | { |
2238 | if (!entry->only_xr) |
2239 | *(unsigned long *)mask |= entry->class->usage_mask; |
2240 | else /* Mask out _READ usage bits */ |
2241 | *(unsigned long *)mask |= (entry->class->usage_mask & LOCKF_IRQ); |
2242 | |
2243 | return false; |
2244 | } |
2245 | |
2246 | /* |
2247 | * There is a strong dependency path in the dependency graph: A -> B, and now |
2248 | * we need to decide which usage bit of B conflicts with the usage bits of A, |
2249 | * i.e. which usage bit of B may introduce safe->unsafe deadlocks. |
2250 | * |
2251 | * As above, if only_xr is false, which means A -> B has -(*N)-> dependency |
2252 | * path, any usage of B should be considered. Otherwise, we should only |
2253 | * consider _READ usage. |
2254 | */ |
2255 | static inline bool usage_match(struct lock_list *entry, void *mask) |
2256 | { |
2257 | if (!entry->only_xr) |
2258 | return !!(entry->class->usage_mask & *(unsigned long *)mask); |
2259 | else /* Mask out _READ usage bits */ |
2260 | return !!((entry->class->usage_mask & LOCKF_IRQ) & *(unsigned long *)mask); |
2261 | } |
2262 | |
2263 | static inline bool usage_skip(struct lock_list *entry, void *mask) |
2264 | { |
2265 | if (entry->class->lock_type == LD_LOCK_NORMAL) |
2266 | return false; |
2267 | |
2268 | /* |
2269 | * Skip local_lock() for irq inversion detection. |
2270 | * |
2271 | * For !RT, local_lock() is not a real lock, so it won't carry any |
2272 | * dependency. |
2273 | * |
2274 | * For RT, an irq inversion happens when we have lock A and B, and on |
2275 | * some CPU we can have: |
2276 | * |
2277 | * lock(A); |
2278 | * <interrupted> |
2279 | * lock(B); |
2280 | * |
2281 | * where lock(B) cannot sleep, and we have a dependency B -> ... -> A. |
2282 | * |
2283 | * Now we prove local_lock() cannot exist in that dependency. First we |
2284 | * have the observation for any lock chain L1 -> ... -> Ln, for any |
2285 | * 1 <= i <= n, Li.inner_wait_type <= L1.inner_wait_type, otherwise |
2286 | * wait context check will complain. And since B is not a sleep lock, |
2287 | * therefore B.inner_wait_type >= 2, and since the inner_wait_type of |
2288 | * local_lock() is 3, which is greater than 2, therefore there is no |
2289 | * way the local_lock() exists in the dependency B -> ... -> A. |
2290 | * |
2291 | * As a result, we will skip local_lock(), when we search for irq |
2292 | * inversion bugs. |
2293 | */ |
2294 | if (entry->class->lock_type == LD_LOCK_PERCPU && |
2295 | DEBUG_LOCKS_WARN_ON(entry->class->wait_type_inner < LD_WAIT_CONFIG)) |
2296 | return false; |
2297 | |
2298 | /* |
2299 | * Skip WAIT_OVERRIDE for irq inversion detection -- it's not actually |
2300 | * a lock and only used to override the wait_type. |
2301 | */ |
2302 | |
2303 | return true; |
2304 | } |
2305 | |
2306 | /* |
2307 | * Find a node in the forwards-direction dependency sub-graph starting |
2308 | * at @root->class that matches @bit. |
2309 | * |
2310 | * Return BFS_MATCH if such a node exists in the subgraph, and put that node |
2311 | * into *@target_entry. |
2312 | */ |
2313 | static enum bfs_result |
2314 | find_usage_forwards(struct lock_list *root, unsigned long usage_mask, |
2315 | struct lock_list **target_entry) |
2316 | { |
2317 | enum bfs_result result; |
2318 | |
2319 | debug_atomic_inc(nr_find_usage_forwards_checks); |
2320 | |
2321 | result = __bfs_forwards(src_entry: root, data: &usage_mask, match: usage_match, skip: usage_skip, target_entry); |
2322 | |
2323 | return result; |
2324 | } |
2325 | |
2326 | /* |
2327 | * Find a node in the backwards-direction dependency sub-graph starting |
2328 | * at @root->class that matches @bit. |
2329 | */ |
2330 | static enum bfs_result |
2331 | find_usage_backwards(struct lock_list *root, unsigned long usage_mask, |
2332 | struct lock_list **target_entry) |
2333 | { |
2334 | enum bfs_result result; |
2335 | |
2336 | debug_atomic_inc(nr_find_usage_backwards_checks); |
2337 | |
2338 | result = __bfs_backwards(src_entry: root, data: &usage_mask, match: usage_match, skip: usage_skip, target_entry); |
2339 | |
2340 | return result; |
2341 | } |
2342 | |
2343 | static void (struct lock_class *class, int depth) |
2344 | { |
2345 | int bit; |
2346 | |
2347 | printk("%*s->" , depth, "" ); |
2348 | print_lock_name(NULL, class); |
2349 | #ifdef CONFIG_DEBUG_LOCKDEP |
2350 | printk(KERN_CONT " ops: %lu" , debug_class_ops_read(class)); |
2351 | #endif |
2352 | printk(KERN_CONT " {\n" ); |
2353 | |
2354 | for (bit = 0; bit < LOCK_TRACE_STATES; bit++) { |
2355 | if (class->usage_mask & (1 << bit)) { |
2356 | int len = depth; |
2357 | |
2358 | len += printk("%*s %s" , depth, "" , usage_str[bit]); |
2359 | len += printk(KERN_CONT " at:\n" ); |
2360 | print_lock_trace(trace: class->usage_traces[bit], spaces: len); |
2361 | } |
2362 | } |
2363 | printk("%*s }\n" , depth, "" ); |
2364 | |
2365 | printk("%*s ... key at: [<%px>] %pS\n" , |
2366 | depth, "" , class->key, class->key); |
2367 | } |
2368 | |
2369 | /* |
2370 | * Dependency path printing: |
2371 | * |
2372 | * After BFS we get a lock dependency path (linked via ->parent of lock_list), |
2373 | * printing out each lock in the dependency path will help on understanding how |
2374 | * the deadlock could happen. Here are some details about dependency path |
2375 | * printing: |
2376 | * |
2377 | * 1) A lock_list can be either forwards or backwards for a lock dependency, |
2378 | * for a lock dependency A -> B, there are two lock_lists: |
2379 | * |
2380 | * a) lock_list in the ->locks_after list of A, whose ->class is B and |
2381 | * ->links_to is A. In this case, we can say the lock_list is |
2382 | * "A -> B" (forwards case). |
2383 | * |
2384 | * b) lock_list in the ->locks_before list of B, whose ->class is A |
2385 | * and ->links_to is B. In this case, we can say the lock_list is |
2386 | * "B <- A" (bacwards case). |
2387 | * |
2388 | * The ->trace of both a) and b) point to the call trace where B was |
2389 | * acquired with A held. |
2390 | * |
2391 | * 2) A "helper" lock_list is introduced during BFS, this lock_list doesn't |
2392 | * represent a certain lock dependency, it only provides an initial entry |
2393 | * for BFS. For example, BFS may introduce a "helper" lock_list whose |
2394 | * ->class is A, as a result BFS will search all dependencies starting with |
2395 | * A, e.g. A -> B or A -> C. |
2396 | * |
2397 | * The notation of a forwards helper lock_list is like "-> A", which means |
2398 | * we should search the forwards dependencies starting with "A", e.g A -> B |
2399 | * or A -> C. |
2400 | * |
2401 | * The notation of a bacwards helper lock_list is like "<- B", which means |
2402 | * we should search the backwards dependencies ending with "B", e.g. |
2403 | * B <- A or B <- C. |
2404 | */ |
2405 | |
2406 | /* |
2407 | * printk the shortest lock dependencies from @root to @leaf in reverse order. |
2408 | * |
2409 | * We have a lock dependency path as follow: |
2410 | * |
2411 | * @root @leaf |
2412 | * | | |
2413 | * V V |
2414 | * ->parent ->parent |
2415 | * | lock_list | <--------- | lock_list | ... | lock_list | <--------- | lock_list | |
2416 | * | -> L1 | | L1 -> L2 | ... |Ln-2 -> Ln-1| | Ln-1 -> Ln| |
2417 | * |
2418 | * , so it's natural that we start from @leaf and print every ->class and |
2419 | * ->trace until we reach the @root. |
2420 | */ |
2421 | static void __used |
2422 | print_shortest_lock_dependencies(struct lock_list *leaf, |
2423 | struct lock_list *root) |
2424 | { |
2425 | struct lock_list *entry = leaf; |
2426 | int depth; |
2427 | |
2428 | /*compute depth from generated tree by BFS*/ |
2429 | depth = get_lock_depth(child: leaf); |
2430 | |
2431 | do { |
2432 | print_lock_class_header(class: entry->class, depth); |
2433 | printk("%*s ... acquired at:\n" , depth, "" ); |
2434 | print_lock_trace(trace: entry->trace, spaces: 2); |
2435 | printk("\n" ); |
2436 | |
2437 | if (depth == 0 && (entry != root)) { |
2438 | printk("lockdep:%s bad path found in chain graph\n" , __func__); |
2439 | break; |
2440 | } |
2441 | |
2442 | entry = get_lock_parent(child: entry); |
2443 | depth--; |
2444 | } while (entry && (depth >= 0)); |
2445 | } |
2446 | |
2447 | /* |
2448 | * printk the shortest lock dependencies from @leaf to @root. |
2449 | * |
2450 | * We have a lock dependency path (from a backwards search) as follow: |
2451 | * |
2452 | * @leaf @root |
2453 | * | | |
2454 | * V V |
2455 | * ->parent ->parent |
2456 | * | lock_list | ---------> | lock_list | ... | lock_list | ---------> | lock_list | |
2457 | * | L2 <- L1 | | L3 <- L2 | ... | Ln <- Ln-1 | | <- Ln | |
2458 | * |
2459 | * , so when we iterate from @leaf to @root, we actually print the lock |
2460 | * dependency path L1 -> L2 -> .. -> Ln in the non-reverse order. |
2461 | * |
2462 | * Another thing to notice here is that ->class of L2 <- L1 is L1, while the |
2463 | * ->trace of L2 <- L1 is the call trace of L2, in fact we don't have the call |
2464 | * trace of L1 in the dependency path, which is alright, because most of the |
2465 | * time we can figure out where L1 is held from the call trace of L2. |
2466 | */ |
2467 | static void __used |
2468 | print_shortest_lock_dependencies_backwards(struct lock_list *leaf, |
2469 | struct lock_list *root) |
2470 | { |
2471 | struct lock_list *entry = leaf; |
2472 | const struct lock_trace *trace = NULL; |
2473 | int depth; |
2474 | |
2475 | /*compute depth from generated tree by BFS*/ |
2476 | depth = get_lock_depth(child: leaf); |
2477 | |
2478 | do { |
2479 | print_lock_class_header(class: entry->class, depth); |
2480 | if (trace) { |
2481 | printk("%*s ... acquired at:\n" , depth, "" ); |
2482 | print_lock_trace(trace, spaces: 2); |
2483 | printk("\n" ); |
2484 | } |
2485 | |
2486 | /* |
2487 | * Record the pointer to the trace for the next lock_list |
2488 | * entry, see the comments for the function. |
2489 | */ |
2490 | trace = entry->trace; |
2491 | |
2492 | if (depth == 0 && (entry != root)) { |
2493 | printk("lockdep:%s bad path found in chain graph\n" , __func__); |
2494 | break; |
2495 | } |
2496 | |
2497 | entry = get_lock_parent(child: entry); |
2498 | depth--; |
2499 | } while (entry && (depth >= 0)); |
2500 | } |
2501 | |
2502 | static void |
2503 | print_irq_lock_scenario(struct lock_list *safe_entry, |
2504 | struct lock_list *unsafe_entry, |
2505 | struct lock_class *prev_class, |
2506 | struct lock_class *next_class) |
2507 | { |
2508 | struct lock_class *safe_class = safe_entry->class; |
2509 | struct lock_class *unsafe_class = unsafe_entry->class; |
2510 | struct lock_class *middle_class = prev_class; |
2511 | |
2512 | if (middle_class == safe_class) |
2513 | middle_class = next_class; |
2514 | |
2515 | /* |
2516 | * A direct locking problem where unsafe_class lock is taken |
2517 | * directly by safe_class lock, then all we need to show |
2518 | * is the deadlock scenario, as it is obvious that the |
2519 | * unsafe lock is taken under the safe lock. |
2520 | * |
2521 | * But if there is a chain instead, where the safe lock takes |
2522 | * an intermediate lock (middle_class) where this lock is |
2523 | * not the same as the safe lock, then the lock chain is |
2524 | * used to describe the problem. Otherwise we would need |
2525 | * to show a different CPU case for each link in the chain |
2526 | * from the safe_class lock to the unsafe_class lock. |
2527 | */ |
2528 | if (middle_class != unsafe_class) { |
2529 | printk("Chain exists of:\n " ); |
2530 | __print_lock_name(NULL, class: safe_class); |
2531 | printk(KERN_CONT " --> " ); |
2532 | __print_lock_name(NULL, class: middle_class); |
2533 | printk(KERN_CONT " --> " ); |
2534 | __print_lock_name(NULL, class: unsafe_class); |
2535 | printk(KERN_CONT "\n\n" ); |
2536 | } |
2537 | |
2538 | printk(" Possible interrupt unsafe locking scenario:\n\n" ); |
2539 | printk(" CPU0 CPU1\n" ); |
2540 | printk(" ---- ----\n" ); |
2541 | printk(" lock(" ); |
2542 | __print_lock_name(NULL, class: unsafe_class); |
2543 | printk(KERN_CONT ");\n" ); |
2544 | printk(" local_irq_disable();\n" ); |
2545 | printk(" lock(" ); |
2546 | __print_lock_name(NULL, class: safe_class); |
2547 | printk(KERN_CONT ");\n" ); |
2548 | printk(" lock(" ); |
2549 | __print_lock_name(NULL, class: middle_class); |
2550 | printk(KERN_CONT ");\n" ); |
2551 | printk(" <Interrupt>\n" ); |
2552 | printk(" lock(" ); |
2553 | __print_lock_name(NULL, class: safe_class); |
2554 | printk(KERN_CONT ");\n" ); |
2555 | printk("\n *** DEADLOCK ***\n\n" ); |
2556 | } |
2557 | |
2558 | static void |
2559 | print_bad_irq_dependency(struct task_struct *curr, |
2560 | struct lock_list *prev_root, |
2561 | struct lock_list *next_root, |
2562 | struct lock_list *backwards_entry, |
2563 | struct lock_list *forwards_entry, |
2564 | struct held_lock *prev, |
2565 | struct held_lock *next, |
2566 | enum lock_usage_bit bit1, |
2567 | enum lock_usage_bit bit2, |
2568 | const char *irqclass) |
2569 | { |
2570 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) |
2571 | return; |
2572 | |
2573 | pr_warn("\n" ); |
2574 | pr_warn("=====================================================\n" ); |
2575 | pr_warn("WARNING: %s-safe -> %s-unsafe lock order detected\n" , |
2576 | irqclass, irqclass); |
2577 | print_kernel_ident(); |
2578 | pr_warn("-----------------------------------------------------\n" ); |
2579 | pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n" , |
2580 | curr->comm, task_pid_nr(curr), |
2581 | lockdep_hardirq_context(), hardirq_count() >> HARDIRQ_SHIFT, |
2582 | curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT, |
2583 | lockdep_hardirqs_enabled(), |
2584 | curr->softirqs_enabled); |
2585 | print_lock(hlock: next); |
2586 | |
2587 | pr_warn("\nand this task is already holding:\n" ); |
2588 | print_lock(hlock: prev); |
2589 | pr_warn("which would create a new lock dependency:\n" ); |
2590 | print_lock_name(hlock: prev, class: hlock_class(hlock: prev)); |
2591 | pr_cont(" ->" ); |
2592 | print_lock_name(hlock: next, class: hlock_class(hlock: next)); |
2593 | pr_cont("\n" ); |
2594 | |
2595 | pr_warn("\nbut this new dependency connects a %s-irq-safe lock:\n" , |
2596 | irqclass); |
2597 | print_lock_name(NULL, class: backwards_entry->class); |
2598 | pr_warn("\n... which became %s-irq-safe at:\n" , irqclass); |
2599 | |
2600 | print_lock_trace(trace: backwards_entry->class->usage_traces[bit1], spaces: 1); |
2601 | |
2602 | pr_warn("\nto a %s-irq-unsafe lock:\n" , irqclass); |
2603 | print_lock_name(NULL, class: forwards_entry->class); |
2604 | pr_warn("\n... which became %s-irq-unsafe at:\n" , irqclass); |
2605 | pr_warn("..." ); |
2606 | |
2607 | print_lock_trace(trace: forwards_entry->class->usage_traces[bit2], spaces: 1); |
2608 | |
2609 | pr_warn("\nother info that might help us debug this:\n\n" ); |
2610 | print_irq_lock_scenario(safe_entry: backwards_entry, unsafe_entry: forwards_entry, |
2611 | prev_class: hlock_class(hlock: prev), next_class: hlock_class(hlock: next)); |
2612 | |
2613 | lockdep_print_held_locks(p: curr); |
2614 | |
2615 | pr_warn("\nthe dependencies between %s-irq-safe lock and the holding lock:\n" , irqclass); |
2616 | print_shortest_lock_dependencies_backwards(leaf: backwards_entry, root: prev_root); |
2617 | |
2618 | pr_warn("\nthe dependencies between the lock to be acquired" ); |
2619 | pr_warn(" and %s-irq-unsafe lock:\n" , irqclass); |
2620 | next_root->trace = save_trace(); |
2621 | if (!next_root->trace) |
2622 | return; |
2623 | print_shortest_lock_dependencies(leaf: forwards_entry, root: next_root); |
2624 | |
2625 | pr_warn("\nstack backtrace:\n" ); |
2626 | dump_stack(); |
2627 | } |
2628 | |
2629 | static const char *state_names[] = { |
2630 | #define LOCKDEP_STATE(__STATE) \ |
2631 | __stringify(__STATE), |
2632 | #include "lockdep_states.h" |
2633 | #undef LOCKDEP_STATE |
2634 | }; |
2635 | |
2636 | static const char *state_rnames[] = { |
2637 | #define LOCKDEP_STATE(__STATE) \ |
2638 | __stringify(__STATE)"-READ", |
2639 | #include "lockdep_states.h" |
2640 | #undef LOCKDEP_STATE |
2641 | }; |
2642 | |
2643 | static inline const char *state_name(enum lock_usage_bit bit) |
2644 | { |
2645 | if (bit & LOCK_USAGE_READ_MASK) |
2646 | return state_rnames[bit >> LOCK_USAGE_DIR_MASK]; |
2647 | else |
2648 | return state_names[bit >> LOCK_USAGE_DIR_MASK]; |
2649 | } |
2650 | |
2651 | /* |
2652 | * The bit number is encoded like: |
2653 | * |
2654 | * bit0: 0 exclusive, 1 read lock |
2655 | * bit1: 0 used in irq, 1 irq enabled |
2656 | * bit2-n: state |
2657 | */ |
2658 | static int exclusive_bit(int new_bit) |
2659 | { |
2660 | int state = new_bit & LOCK_USAGE_STATE_MASK; |
2661 | int dir = new_bit & LOCK_USAGE_DIR_MASK; |
2662 | |
2663 | /* |
2664 | * keep state, bit flip the direction and strip read. |
2665 | */ |
2666 | return state | (dir ^ LOCK_USAGE_DIR_MASK); |
2667 | } |
2668 | |
2669 | /* |
2670 | * Observe that when given a bitmask where each bitnr is encoded as above, a |
2671 | * right shift of the mask transforms the individual bitnrs as -1 and |
2672 | * conversely, a left shift transforms into +1 for the individual bitnrs. |
2673 | * |
2674 | * So for all bits whose number have LOCK_ENABLED_* set (bitnr1 == 1), we can |
2675 | * create the mask with those bit numbers using LOCK_USED_IN_* (bitnr1 == 0) |
2676 | * instead by subtracting the bit number by 2, or shifting the mask right by 2. |
2677 | * |
2678 | * Similarly, bitnr1 == 0 becomes bitnr1 == 1 by adding 2, or shifting left 2. |
2679 | * |
2680 | * So split the mask (note that LOCKF_ENABLED_IRQ_ALL|LOCKF_USED_IN_IRQ_ALL is |
2681 | * all bits set) and recompose with bitnr1 flipped. |
2682 | */ |
2683 | static unsigned long invert_dir_mask(unsigned long mask) |
2684 | { |
2685 | unsigned long excl = 0; |
2686 | |
2687 | /* Invert dir */ |
2688 | excl |= (mask & LOCKF_ENABLED_IRQ_ALL) >> LOCK_USAGE_DIR_MASK; |
2689 | excl |= (mask & LOCKF_USED_IN_IRQ_ALL) << LOCK_USAGE_DIR_MASK; |
2690 | |
2691 | return excl; |
2692 | } |
2693 | |
2694 | /* |
2695 | * Note that a LOCK_ENABLED_IRQ_*_READ usage and a LOCK_USED_IN_IRQ_*_READ |
2696 | * usage may cause deadlock too, for example: |
2697 | * |
2698 | * P1 P2 |
2699 | * <irq disabled> |
2700 | * write_lock(l1); <irq enabled> |
2701 | * read_lock(l2); |
2702 | * write_lock(l2); |
2703 | * <in irq> |
2704 | * read_lock(l1); |
2705 | * |
2706 | * , in above case, l1 will be marked as LOCK_USED_IN_IRQ_HARDIRQ_READ and l2 |
2707 | * will marked as LOCK_ENABLE_IRQ_HARDIRQ_READ, and this is a possible |
2708 | * deadlock. |
2709 | * |
2710 | * In fact, all of the following cases may cause deadlocks: |
2711 | * |
2712 | * LOCK_USED_IN_IRQ_* -> LOCK_ENABLED_IRQ_* |
2713 | * LOCK_USED_IN_IRQ_*_READ -> LOCK_ENABLED_IRQ_* |
2714 | * LOCK_USED_IN_IRQ_* -> LOCK_ENABLED_IRQ_*_READ |
2715 | * LOCK_USED_IN_IRQ_*_READ -> LOCK_ENABLED_IRQ_*_READ |
2716 | * |
2717 | * As a result, to calculate the "exclusive mask", first we invert the |
2718 | * direction (USED_IN/ENABLED) of the original mask, and 1) for all bits with |
2719 | * bitnr0 set (LOCK_*_READ), add those with bitnr0 cleared (LOCK_*). 2) for all |
2720 | * bits with bitnr0 cleared (LOCK_*_READ), add those with bitnr0 set (LOCK_*). |
2721 | */ |
2722 | static unsigned long exclusive_mask(unsigned long mask) |
2723 | { |
2724 | unsigned long excl = invert_dir_mask(mask); |
2725 | |
2726 | excl |= (excl & LOCKF_IRQ_READ) >> LOCK_USAGE_READ_MASK; |
2727 | excl |= (excl & LOCKF_IRQ) << LOCK_USAGE_READ_MASK; |
2728 | |
2729 | return excl; |
2730 | } |
2731 | |
2732 | /* |
2733 | * Retrieve the _possible_ original mask to which @mask is |
2734 | * exclusive. Ie: this is the opposite of exclusive_mask(). |
2735 | * Note that 2 possible original bits can match an exclusive |
2736 | * bit: one has LOCK_USAGE_READ_MASK set, the other has it |
2737 | * cleared. So both are returned for each exclusive bit. |
2738 | */ |
2739 | static unsigned long original_mask(unsigned long mask) |
2740 | { |
2741 | unsigned long excl = invert_dir_mask(mask); |
2742 | |
2743 | /* Include read in existing usages */ |
2744 | excl |= (excl & LOCKF_IRQ_READ) >> LOCK_USAGE_READ_MASK; |
2745 | excl |= (excl & LOCKF_IRQ) << LOCK_USAGE_READ_MASK; |
2746 | |
2747 | return excl; |
2748 | } |
2749 | |
2750 | /* |
2751 | * Find the first pair of bit match between an original |
2752 | * usage mask and an exclusive usage mask. |
2753 | */ |
2754 | static int find_exclusive_match(unsigned long mask, |
2755 | unsigned long excl_mask, |
2756 | enum lock_usage_bit *bitp, |
2757 | enum lock_usage_bit *excl_bitp) |
2758 | { |
2759 | int bit, excl, excl_read; |
2760 | |
2761 | for_each_set_bit(bit, &mask, LOCK_USED) { |
2762 | /* |
2763 | * exclusive_bit() strips the read bit, however, |
2764 | * LOCK_ENABLED_IRQ_*_READ may cause deadlocks too, so we need |
2765 | * to search excl | LOCK_USAGE_READ_MASK as well. |
2766 | */ |
2767 | excl = exclusive_bit(new_bit: bit); |
2768 | excl_read = excl | LOCK_USAGE_READ_MASK; |
2769 | if (excl_mask & lock_flag(bit: excl)) { |
2770 | *bitp = bit; |
2771 | *excl_bitp = excl; |
2772 | return 0; |
2773 | } else if (excl_mask & lock_flag(bit: excl_read)) { |
2774 | *bitp = bit; |
2775 | *excl_bitp = excl_read; |
2776 | return 0; |
2777 | } |
2778 | } |
2779 | return -1; |
2780 | } |
2781 | |
2782 | /* |
2783 | * Prove that the new dependency does not connect a hardirq-safe(-read) |
2784 | * lock with a hardirq-unsafe lock - to achieve this we search |
2785 | * the backwards-subgraph starting at <prev>, and the |
2786 | * forwards-subgraph starting at <next>: |
2787 | */ |
2788 | static int check_irq_usage(struct task_struct *curr, struct held_lock *prev, |
2789 | struct held_lock *next) |
2790 | { |
2791 | unsigned long usage_mask = 0, forward_mask, backward_mask; |
2792 | enum lock_usage_bit forward_bit = 0, backward_bit = 0; |
2793 | struct lock_list *target_entry1; |
2794 | struct lock_list *target_entry; |
2795 | struct lock_list this, that; |
2796 | enum bfs_result ret; |
2797 | |
2798 | /* |
2799 | * Step 1: gather all hard/soft IRQs usages backward in an |
2800 | * accumulated usage mask. |
2801 | */ |
2802 | bfs_init_rootb(lock: &this, hlock: prev); |
2803 | |
2804 | ret = __bfs_backwards(src_entry: &this, data: &usage_mask, match: usage_accumulate, skip: usage_skip, NULL); |
2805 | if (bfs_error(res: ret)) { |
2806 | print_bfs_bug(ret); |
2807 | return 0; |
2808 | } |
2809 | |
2810 | usage_mask &= LOCKF_USED_IN_IRQ_ALL; |
2811 | if (!usage_mask) |
2812 | return 1; |
2813 | |
2814 | /* |
2815 | * Step 2: find exclusive uses forward that match the previous |
2816 | * backward accumulated mask. |
2817 | */ |
2818 | forward_mask = exclusive_mask(mask: usage_mask); |
2819 | |
2820 | bfs_init_root(lock: &that, hlock: next); |
2821 | |
2822 | ret = find_usage_forwards(root: &that, usage_mask: forward_mask, target_entry: &target_entry1); |
2823 | if (bfs_error(res: ret)) { |
2824 | print_bfs_bug(ret); |
2825 | return 0; |
2826 | } |
2827 | if (ret == BFS_RNOMATCH) |
2828 | return 1; |
2829 | |
2830 | /* |
2831 | * Step 3: we found a bad match! Now retrieve a lock from the backward |
2832 | * list whose usage mask matches the exclusive usage mask from the |
2833 | * lock found on the forward list. |
2834 | * |
2835 | * Note, we should only keep the LOCKF_ENABLED_IRQ_ALL bits, considering |
2836 | * the follow case: |
2837 | * |
2838 | * When trying to add A -> B to the graph, we find that there is a |
2839 | * hardirq-safe L, that L -> ... -> A, and another hardirq-unsafe M, |
2840 | * that B -> ... -> M. However M is **softirq-safe**, if we use exact |
2841 | * invert bits of M's usage_mask, we will find another lock N that is |
2842 | * **softirq-unsafe** and N -> ... -> A, however N -> .. -> M will not |
2843 | * cause a inversion deadlock. |
2844 | */ |
2845 | backward_mask = original_mask(mask: target_entry1->class->usage_mask & LOCKF_ENABLED_IRQ_ALL); |
2846 | |
2847 | ret = find_usage_backwards(root: &this, usage_mask: backward_mask, target_entry: &target_entry); |
2848 | if (bfs_error(res: ret)) { |
2849 | print_bfs_bug(ret); |
2850 | return 0; |
2851 | } |
2852 | if (DEBUG_LOCKS_WARN_ON(ret == BFS_RNOMATCH)) |
2853 | return 1; |
2854 | |
2855 | /* |
2856 | * Step 4: narrow down to a pair of incompatible usage bits |
2857 | * and report it. |
2858 | */ |
2859 | ret = find_exclusive_match(mask: target_entry->class->usage_mask, |
2860 | excl_mask: target_entry1->class->usage_mask, |
2861 | bitp: &backward_bit, excl_bitp: &forward_bit); |
2862 | if (DEBUG_LOCKS_WARN_ON(ret == -1)) |
2863 | return 1; |
2864 | |
2865 | print_bad_irq_dependency(curr, prev_root: &this, next_root: &that, |
2866 | backwards_entry: target_entry, forwards_entry: target_entry1, |
2867 | prev, next, |
2868 | bit1: backward_bit, bit2: forward_bit, |
2869 | irqclass: state_name(bit: backward_bit)); |
2870 | |
2871 | return 0; |
2872 | } |
2873 | |
2874 | #else |
2875 | |
2876 | static inline int check_irq_usage(struct task_struct *curr, |
2877 | struct held_lock *prev, struct held_lock *next) |
2878 | { |
2879 | return 1; |
2880 | } |
2881 | |
2882 | static inline bool usage_skip(struct lock_list *entry, void *mask) |
2883 | { |
2884 | return false; |
2885 | } |
2886 | |
2887 | #endif /* CONFIG_TRACE_IRQFLAGS */ |
2888 | |
2889 | #ifdef CONFIG_LOCKDEP_SMALL |
2890 | /* |
2891 | * Check that the dependency graph starting at <src> can lead to |
2892 | * <target> or not. If it can, <src> -> <target> dependency is already |
2893 | * in the graph. |
2894 | * |
2895 | * Return BFS_RMATCH if it does, or BFS_RNOMATCH if it does not, return BFS_E* if |
2896 | * any error appears in the bfs search. |
2897 | */ |
2898 | static noinline enum bfs_result |
2899 | check_redundant(struct held_lock *src, struct held_lock *target) |
2900 | { |
2901 | enum bfs_result ret; |
2902 | struct lock_list *target_entry; |
2903 | struct lock_list src_entry; |
2904 | |
2905 | bfs_init_root(&src_entry, src); |
2906 | /* |
2907 | * Special setup for check_redundant(). |
2908 | * |
2909 | * To report redundant, we need to find a strong dependency path that |
2910 | * is equal to or stronger than <src> -> <target>. So if <src> is E, |
2911 | * we need to let __bfs() only search for a path starting at a -(E*)->, |
2912 | * we achieve this by setting the initial node's ->only_xr to true in |
2913 | * that case. And if <prev> is S, we set initial ->only_xr to false |
2914 | * because both -(S*)-> (equal) and -(E*)-> (stronger) are redundant. |
2915 | */ |
2916 | src_entry.only_xr = src->read == 0; |
2917 | |
2918 | debug_atomic_inc(nr_redundant_checks); |
2919 | |
2920 | /* |
2921 | * Note: we skip local_lock() for redundant check, because as the |
2922 | * comment in usage_skip(), A -> local_lock() -> B and A -> B are not |
2923 | * the same. |
2924 | */ |
2925 | ret = check_path(target, &src_entry, hlock_equal, usage_skip, &target_entry); |
2926 | |
2927 | if (ret == BFS_RMATCH) |
2928 | debug_atomic_inc(nr_redundant); |
2929 | |
2930 | return ret; |
2931 | } |
2932 | |
2933 | #else |
2934 | |
2935 | static inline enum bfs_result |
2936 | check_redundant(struct held_lock *src, struct held_lock *target) |
2937 | { |
2938 | return BFS_RNOMATCH; |
2939 | } |
2940 | |
2941 | #endif |
2942 | |
2943 | static void inc_chains(int irq_context) |
2944 | { |
2945 | if (irq_context & LOCK_CHAIN_HARDIRQ_CONTEXT) |
2946 | nr_hardirq_chains++; |
2947 | else if (irq_context & LOCK_CHAIN_SOFTIRQ_CONTEXT) |
2948 | nr_softirq_chains++; |
2949 | else |
2950 | nr_process_chains++; |
2951 | } |
2952 | |
2953 | static void dec_chains(int irq_context) |
2954 | { |
2955 | if (irq_context & LOCK_CHAIN_HARDIRQ_CONTEXT) |
2956 | nr_hardirq_chains--; |
2957 | else if (irq_context & LOCK_CHAIN_SOFTIRQ_CONTEXT) |
2958 | nr_softirq_chains--; |
2959 | else |
2960 | nr_process_chains--; |
2961 | } |
2962 | |
2963 | static void |
2964 | print_deadlock_scenario(struct held_lock *nxt, struct held_lock *prv) |
2965 | { |
2966 | struct lock_class *next = hlock_class(hlock: nxt); |
2967 | struct lock_class *prev = hlock_class(hlock: prv); |
2968 | |
2969 | printk(" Possible unsafe locking scenario:\n\n" ); |
2970 | printk(" CPU0\n" ); |
2971 | printk(" ----\n" ); |
2972 | printk(" lock(" ); |
2973 | __print_lock_name(hlock: prv, class: prev); |
2974 | printk(KERN_CONT ");\n" ); |
2975 | printk(" lock(" ); |
2976 | __print_lock_name(hlock: nxt, class: next); |
2977 | printk(KERN_CONT ");\n" ); |
2978 | printk("\n *** DEADLOCK ***\n\n" ); |
2979 | printk(" May be due to missing lock nesting notation\n\n" ); |
2980 | } |
2981 | |
2982 | static void |
2983 | print_deadlock_bug(struct task_struct *curr, struct held_lock *prev, |
2984 | struct held_lock *next) |
2985 | { |
2986 | struct lock_class *class = hlock_class(hlock: prev); |
2987 | |
2988 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) |
2989 | return; |
2990 | |
2991 | pr_warn("\n" ); |
2992 | pr_warn("============================================\n" ); |
2993 | pr_warn("WARNING: possible recursive locking detected\n" ); |
2994 | print_kernel_ident(); |
2995 | pr_warn("--------------------------------------------\n" ); |
2996 | pr_warn("%s/%d is trying to acquire lock:\n" , |
2997 | curr->comm, task_pid_nr(curr)); |
2998 | print_lock(hlock: next); |
2999 | pr_warn("\nbut task is already holding lock:\n" ); |
3000 | print_lock(hlock: prev); |
3001 | |
3002 | if (class->cmp_fn) { |
3003 | pr_warn("and the lock comparison function returns %i:\n" , |
3004 | class->cmp_fn(prev->instance, next->instance)); |
3005 | } |
3006 | |
3007 | pr_warn("\nother info that might help us debug this:\n" ); |
3008 | print_deadlock_scenario(nxt: next, prv: prev); |
3009 | lockdep_print_held_locks(p: curr); |
3010 | |
3011 | pr_warn("\nstack backtrace:\n" ); |
3012 | dump_stack(); |
3013 | } |
3014 | |
3015 | /* |
3016 | * Check whether we are holding such a class already. |
3017 | * |
3018 | * (Note that this has to be done separately, because the graph cannot |
3019 | * detect such classes of deadlocks.) |
3020 | * |
3021 | * Returns: 0 on deadlock detected, 1 on OK, 2 if another lock with the same |
3022 | * lock class is held but nest_lock is also held, i.e. we rely on the |
3023 | * nest_lock to avoid the deadlock. |
3024 | */ |
3025 | static int |
3026 | check_deadlock(struct task_struct *curr, struct held_lock *next) |
3027 | { |
3028 | struct lock_class *class; |
3029 | struct held_lock *prev; |
3030 | struct held_lock *nest = NULL; |
3031 | int i; |
3032 | |
3033 | for (i = 0; i < curr->lockdep_depth; i++) { |
3034 | prev = curr->held_locks + i; |
3035 | |
3036 | if (prev->instance == next->nest_lock) |
3037 | nest = prev; |
3038 | |
3039 | if (hlock_class(hlock: prev) != hlock_class(hlock: next)) |
3040 | continue; |
3041 | |
3042 | /* |
3043 | * Allow read-after-read recursion of the same |
3044 | * lock class (i.e. read_lock(lock)+read_lock(lock)): |
3045 | */ |
3046 | if ((next->read == 2) && prev->read) |
3047 | continue; |
3048 | |
3049 | class = hlock_class(hlock: prev); |
3050 | |
3051 | if (class->cmp_fn && |
3052 | class->cmp_fn(prev->instance, next->instance) < 0) |
3053 | continue; |
3054 | |
3055 | /* |
3056 | * We're holding the nest_lock, which serializes this lock's |
3057 | * nesting behaviour. |
3058 | */ |
3059 | if (nest) |
3060 | return 2; |
3061 | |
3062 | print_deadlock_bug(curr, prev, next); |
3063 | return 0; |
3064 | } |
3065 | return 1; |
3066 | } |
3067 | |
3068 | /* |
3069 | * There was a chain-cache miss, and we are about to add a new dependency |
3070 | * to a previous lock. We validate the following rules: |
3071 | * |
3072 | * - would the adding of the <prev> -> <next> dependency create a |
3073 | * circular dependency in the graph? [== circular deadlock] |
3074 | * |
3075 | * - does the new prev->next dependency connect any hardirq-safe lock |
3076 | * (in the full backwards-subgraph starting at <prev>) with any |
3077 | * hardirq-unsafe lock (in the full forwards-subgraph starting at |
3078 | * <next>)? [== illegal lock inversion with hardirq contexts] |
3079 | * |
3080 | * - does the new prev->next dependency connect any softirq-safe lock |
3081 | * (in the full backwards-subgraph starting at <prev>) with any |
3082 | * softirq-unsafe lock (in the full forwards-subgraph starting at |
3083 | * <next>)? [== illegal lock inversion with softirq contexts] |
3084 | * |
3085 | * any of these scenarios could lead to a deadlock. |
3086 | * |
3087 | * Then if all the validations pass, we add the forwards and backwards |
3088 | * dependency. |
3089 | */ |
3090 | static int |
3091 | check_prev_add(struct task_struct *curr, struct held_lock *prev, |
3092 | struct held_lock *next, u16 distance, |
3093 | struct lock_trace **const trace) |
3094 | { |
3095 | struct lock_list *entry; |
3096 | enum bfs_result ret; |
3097 | |
3098 | if (!hlock_class(hlock: prev)->key || !hlock_class(hlock: next)->key) { |
3099 | /* |
3100 | * The warning statements below may trigger a use-after-free |
3101 | * of the class name. It is better to trigger a use-after free |
3102 | * and to have the class name most of the time instead of not |
3103 | * having the class name available. |
3104 | */ |
3105 | WARN_ONCE(!debug_locks_silent && !hlock_class(prev)->key, |
3106 | "Detected use-after-free of lock class %px/%s\n" , |
3107 | hlock_class(prev), |
3108 | hlock_class(prev)->name); |
3109 | WARN_ONCE(!debug_locks_silent && !hlock_class(next)->key, |
3110 | "Detected use-after-free of lock class %px/%s\n" , |
3111 | hlock_class(next), |
3112 | hlock_class(next)->name); |
3113 | return 2; |
3114 | } |
3115 | |
3116 | if (prev->class_idx == next->class_idx) { |
3117 | struct lock_class *class = hlock_class(hlock: prev); |
3118 | |
3119 | if (class->cmp_fn && |
3120 | class->cmp_fn(prev->instance, next->instance) < 0) |
3121 | return 2; |
3122 | } |
3123 | |
3124 | /* |
3125 | * Prove that the new <prev> -> <next> dependency would not |
3126 | * create a circular dependency in the graph. (We do this by |
3127 | * a breadth-first search into the graph starting at <next>, |
3128 | * and check whether we can reach <prev>.) |
3129 | * |
3130 | * The search is limited by the size of the circular queue (i.e., |
3131 | * MAX_CIRCULAR_QUEUE_SIZE) which keeps track of a breadth of nodes |
3132 | * in the graph whose neighbours are to be checked. |
3133 | */ |
3134 | ret = check_noncircular(src: next, target: prev, trace); |
3135 | if (unlikely(bfs_error(ret) || ret == BFS_RMATCH)) |
3136 | return 0; |
3137 | |
3138 | if (!check_irq_usage(curr, prev, next)) |
3139 | return 0; |
3140 | |
3141 | /* |
3142 | * Is the <prev> -> <next> dependency already present? |
3143 | * |
3144 | * (this may occur even though this is a new chain: consider |
3145 | * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3 |
3146 | * chains - the second one will be new, but L1 already has |
3147 | * L2 added to its dependency list, due to the first chain.) |
3148 | */ |
3149 | list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) { |
3150 | if (entry->class == hlock_class(hlock: next)) { |
3151 | if (distance == 1) |
3152 | entry->distance = 1; |
3153 | entry->dep |= calc_dep(prev, next); |
3154 | |
3155 | /* |
3156 | * Also, update the reverse dependency in @next's |
3157 | * ->locks_before list. |
3158 | * |
3159 | * Here we reuse @entry as the cursor, which is fine |
3160 | * because we won't go to the next iteration of the |
3161 | * outer loop: |
3162 | * |
3163 | * For normal cases, we return in the inner loop. |
3164 | * |
3165 | * If we fail to return, we have inconsistency, i.e. |
3166 | * <prev>::locks_after contains <next> while |
3167 | * <next>::locks_before doesn't contain <prev>. In |
3168 | * that case, we return after the inner and indicate |
3169 | * something is wrong. |
3170 | */ |
3171 | list_for_each_entry(entry, &hlock_class(next)->locks_before, entry) { |
3172 | if (entry->class == hlock_class(hlock: prev)) { |
3173 | if (distance == 1) |
3174 | entry->distance = 1; |
3175 | entry->dep |= calc_depb(prev, next); |
3176 | return 1; |
3177 | } |
3178 | } |
3179 | |
3180 | /* <prev> is not found in <next>::locks_before */ |
3181 | return 0; |
3182 | } |
3183 | } |
3184 | |
3185 | /* |
3186 | * Is the <prev> -> <next> link redundant? |
3187 | */ |
3188 | ret = check_redundant(src: prev, target: next); |
3189 | if (bfs_error(res: ret)) |
3190 | return 0; |
3191 | else if (ret == BFS_RMATCH) |
3192 | return 2; |
3193 | |
3194 | if (!*trace) { |
3195 | *trace = save_trace(); |
3196 | if (!*trace) |
3197 | return 0; |
3198 | } |
3199 | |
3200 | /* |
3201 | * Ok, all validations passed, add the new lock |
3202 | * to the previous lock's dependency list: |
3203 | */ |
3204 | ret = add_lock_to_list(this: hlock_class(hlock: next), links_to: hlock_class(hlock: prev), |
3205 | head: &hlock_class(hlock: prev)->locks_after, distance, |
3206 | dep: calc_dep(prev, next), trace: *trace); |
3207 | |
3208 | if (!ret) |
3209 | return 0; |
3210 | |
3211 | ret = add_lock_to_list(this: hlock_class(hlock: prev), links_to: hlock_class(hlock: next), |
3212 | head: &hlock_class(hlock: next)->locks_before, distance, |
3213 | dep: calc_depb(prev, next), trace: *trace); |
3214 | if (!ret) |
3215 | return 0; |
3216 | |
3217 | return 2; |
3218 | } |
3219 | |
3220 | /* |
3221 | * Add the dependency to all directly-previous locks that are 'relevant'. |
3222 | * The ones that are relevant are (in increasing distance from curr): |
3223 | * all consecutive trylock entries and the final non-trylock entry - or |
3224 | * the end of this context's lock-chain - whichever comes first. |
3225 | */ |
3226 | static int |
3227 | check_prevs_add(struct task_struct *curr, struct held_lock *next) |
3228 | { |
3229 | struct lock_trace *trace = NULL; |
3230 | int depth = curr->lockdep_depth; |
3231 | struct held_lock *hlock; |
3232 | |
3233 | /* |
3234 | * Debugging checks. |
3235 | * |
3236 | * Depth must not be zero for a non-head lock: |
3237 | */ |
3238 | if (!depth) |
3239 | goto out_bug; |
3240 | /* |
3241 | * At least two relevant locks must exist for this |
3242 | * to be a head: |
3243 | */ |
3244 | if (curr->held_locks[depth].irq_context != |
3245 | curr->held_locks[depth-1].irq_context) |
3246 | goto out_bug; |
3247 | |
3248 | for (;;) { |
3249 | u16 distance = curr->lockdep_depth - depth + 1; |
3250 | hlock = curr->held_locks + depth - 1; |
3251 | |
3252 | if (hlock->check) { |
3253 | int ret = check_prev_add(curr, prev: hlock, next, distance, trace: &trace); |
3254 | if (!ret) |
3255 | return 0; |
3256 | |
3257 | /* |
3258 | * Stop after the first non-trylock entry, |
3259 | * as non-trylock entries have added their |
3260 | * own direct dependencies already, so this |
3261 | * lock is connected to them indirectly: |
3262 | */ |
3263 | if (!hlock->trylock) |
3264 | break; |
3265 | } |
3266 | |
3267 | depth--; |
3268 | /* |
3269 | * End of lock-stack? |
3270 | */ |
3271 | if (!depth) |
3272 | break; |
3273 | /* |
3274 | * Stop the search if we cross into another context: |
3275 | */ |
3276 | if (curr->held_locks[depth].irq_context != |
3277 | curr->held_locks[depth-1].irq_context) |
3278 | break; |
3279 | } |
3280 | return 1; |
3281 | out_bug: |
3282 | if (!debug_locks_off_graph_unlock()) |
3283 | return 0; |
3284 | |
3285 | /* |
3286 | * Clearly we all shouldn't be here, but since we made it we |
3287 | * can reliable say we messed up our state. See the above two |
3288 | * gotos for reasons why we could possibly end up here. |
3289 | */ |
3290 | WARN_ON(1); |
3291 | |
3292 | return 0; |
3293 | } |
3294 | |
3295 | struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS]; |
3296 | static DECLARE_BITMAP(lock_chains_in_use, MAX_LOCKDEP_CHAINS); |
3297 | static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS]; |
3298 | unsigned long nr_zapped_lock_chains; |
3299 | unsigned int nr_free_chain_hlocks; /* Free chain_hlocks in buckets */ |
3300 | unsigned int nr_lost_chain_hlocks; /* Lost chain_hlocks */ |
3301 | unsigned int nr_large_chain_blocks; /* size > MAX_CHAIN_BUCKETS */ |
3302 | |
3303 | /* |
3304 | * The first 2 chain_hlocks entries in the chain block in the bucket |
3305 | * list contains the following meta data: |
3306 | * |
3307 | * entry[0]: |
3308 | * Bit 15 - always set to 1 (it is not a class index) |
3309 | * Bits 0-14 - upper 15 bits of the next block index |
3310 | * entry[1] - lower 16 bits of next block index |
3311 | * |
3312 | * A next block index of all 1 bits means it is the end of the list. |
3313 | * |
3314 | * On the unsized bucket (bucket-0), the 3rd and 4th entries contain |
3315 | * the chain block size: |
3316 | * |
3317 | * entry[2] - upper 16 bits of the chain block size |
3318 | * entry[3] - lower 16 bits of the chain block size |
3319 | */ |
3320 | #define MAX_CHAIN_BUCKETS 16 |
3321 | #define CHAIN_BLK_FLAG (1U << 15) |
3322 | #define CHAIN_BLK_LIST_END 0xFFFFU |
3323 | |
3324 | static int chain_block_buckets[MAX_CHAIN_BUCKETS]; |
3325 | |
3326 | static inline int size_to_bucket(int size) |
3327 | { |
3328 | if (size > MAX_CHAIN_BUCKETS) |
3329 | return 0; |
3330 | |
3331 | return size - 1; |
3332 | } |
3333 | |
3334 | /* |
3335 | * Iterate all the chain blocks in a bucket. |
3336 | */ |
3337 | #define for_each_chain_block(bucket, prev, curr) \ |
3338 | for ((prev) = -1, (curr) = chain_block_buckets[bucket]; \ |
3339 | (curr) >= 0; \ |
3340 | (prev) = (curr), (curr) = chain_block_next(curr)) |
3341 | |
3342 | /* |
3343 | * next block or -1 |
3344 | */ |
3345 | static inline int chain_block_next(int offset) |
3346 | { |
3347 | int next = chain_hlocks[offset]; |
3348 | |
3349 | WARN_ON_ONCE(!(next & CHAIN_BLK_FLAG)); |
3350 | |
3351 | if (next == CHAIN_BLK_LIST_END) |
3352 | return -1; |
3353 | |
3354 | next &= ~CHAIN_BLK_FLAG; |
3355 | next <<= 16; |
3356 | next |= chain_hlocks[offset + 1]; |
3357 | |
3358 | return next; |
3359 | } |
3360 | |
3361 | /* |
3362 | * bucket-0 only |
3363 | */ |
3364 | static inline int chain_block_size(int offset) |
3365 | { |
3366 | return (chain_hlocks[offset + 2] << 16) | chain_hlocks[offset + 3]; |
3367 | } |
3368 | |
3369 | static inline void init_chain_block(int offset, int next, int bucket, int size) |
3370 | { |
3371 | chain_hlocks[offset] = (next >> 16) | CHAIN_BLK_FLAG; |
3372 | chain_hlocks[offset + 1] = (u16)next; |
3373 | |
3374 | if (size && !bucket) { |
3375 | chain_hlocks[offset + 2] = size >> 16; |
3376 | chain_hlocks[offset + 3] = (u16)size; |
3377 | } |
3378 | } |
3379 | |
3380 | static inline void add_chain_block(int offset, int size) |
3381 | { |
3382 | int bucket = size_to_bucket(size); |
3383 | int next = chain_block_buckets[bucket]; |
3384 | int prev, curr; |
3385 | |
3386 | if (unlikely(size < 2)) { |
3387 | /* |
3388 | * We can't store single entries on the freelist. Leak them. |
3389 | * |
3390 | * One possible way out would be to uniquely mark them, other |
3391 | * than with CHAIN_BLK_FLAG, such that we can recover them when |
3392 | * the block before it is re-added. |
3393 | */ |
3394 | if (size) |
3395 | nr_lost_chain_hlocks++; |
3396 | return; |
3397 | } |
3398 | |
3399 | nr_free_chain_hlocks += size; |
3400 | if (!bucket) { |
3401 | nr_large_chain_blocks++; |
3402 | |
3403 | /* |
3404 | * Variable sized, sort large to small. |
3405 | */ |
3406 | for_each_chain_block(0, prev, curr) { |
3407 | if (size >= chain_block_size(offset: curr)) |
3408 | break; |
3409 | } |
3410 | init_chain_block(offset, next: curr, bucket: 0, size); |
3411 | if (prev < 0) |
3412 | chain_block_buckets[0] = offset; |
3413 | else |
3414 | init_chain_block(offset: prev, next: offset, bucket: 0, size: 0); |
3415 | return; |
3416 | } |
3417 | /* |
3418 | * Fixed size, add to head. |
3419 | */ |
3420 | init_chain_block(offset, next, bucket, size); |
3421 | chain_block_buckets[bucket] = offset; |
3422 | } |
3423 | |
3424 | /* |
3425 | * Only the first block in the list can be deleted. |
3426 | * |
3427 | * For the variable size bucket[0], the first block (the largest one) is |
3428 | * returned, broken up and put back into the pool. So if a chain block of |
3429 | * length > MAX_CHAIN_BUCKETS is ever used and zapped, it will just be |
3430 | * queued up after the primordial chain block and never be used until the |
3431 | * hlock entries in the primordial chain block is almost used up. That |
3432 | * causes fragmentation and reduce allocation efficiency. That can be |
3433 | * monitored by looking at the "large chain blocks" number in lockdep_stats. |
3434 | */ |
3435 | static inline void del_chain_block(int bucket, int size, int next) |
3436 | { |
3437 | nr_free_chain_hlocks -= size; |
3438 | chain_block_buckets[bucket] = next; |
3439 | |
3440 | if (!bucket) |
3441 | nr_large_chain_blocks--; |
3442 | } |
3443 | |
3444 | static void init_chain_block_buckets(void) |
3445 | { |
3446 | int i; |
3447 | |
3448 | for (i = 0; i < MAX_CHAIN_BUCKETS; i++) |
3449 | chain_block_buckets[i] = -1; |
3450 | |
3451 | add_chain_block(offset: 0, ARRAY_SIZE(chain_hlocks)); |
3452 | } |
3453 | |
3454 | /* |
3455 | * Return offset of a chain block of the right size or -1 if not found. |
3456 | * |
3457 | * Fairly simple worst-fit allocator with the addition of a number of size |
3458 | * specific free lists. |
3459 | */ |
3460 | static int alloc_chain_hlocks(int req) |
3461 | { |
3462 | int bucket, curr, size; |
3463 | |
3464 | /* |
3465 | * We rely on the MSB to act as an escape bit to denote freelist |
3466 | * pointers. Make sure this bit isn't set in 'normal' class_idx usage. |
3467 | */ |
3468 | BUILD_BUG_ON((MAX_LOCKDEP_KEYS-1) & CHAIN_BLK_FLAG); |
3469 | |
3470 | init_data_structures_once(); |
3471 | |
3472 | if (nr_free_chain_hlocks < req) |
3473 | return -1; |
3474 | |
3475 | /* |
3476 | * We require a minimum of 2 (u16) entries to encode a freelist |
3477 | * 'pointer'. |
3478 | */ |
3479 | req = max(req, 2); |
3480 | bucket = size_to_bucket(size: req); |
3481 | curr = chain_block_buckets[bucket]; |
3482 | |
3483 | if (bucket) { |
3484 | if (curr >= 0) { |
3485 | del_chain_block(bucket, size: req, next: chain_block_next(offset: curr)); |
3486 | return curr; |
3487 | } |
3488 | /* Try bucket 0 */ |
3489 | curr = chain_block_buckets[0]; |
3490 | } |
3491 | |
3492 | /* |
3493 | * The variable sized freelist is sorted by size; the first entry is |
3494 | * the largest. Use it if it fits. |
3495 | */ |
3496 | if (curr >= 0) { |
3497 | size = chain_block_size(offset: curr); |
3498 | if (likely(size >= req)) { |
3499 | del_chain_block(bucket: 0, size, next: chain_block_next(offset: curr)); |
3500 | add_chain_block(offset: curr + req, size: size - req); |
3501 | return curr; |
3502 | } |
3503 | } |
3504 | |
3505 | /* |
3506 | * Last resort, split a block in a larger sized bucket. |
3507 | */ |
3508 | for (size = MAX_CHAIN_BUCKETS; size > req; size--) { |
3509 | bucket = size_to_bucket(size); |
3510 | curr = chain_block_buckets[bucket]; |
3511 | if (curr < 0) |
3512 | continue; |
3513 | |
3514 | del_chain_block(bucket, size, next: chain_block_next(offset: curr)); |
3515 | add_chain_block(offset: curr + req, size: size - req); |
3516 | return curr; |
3517 | } |
3518 | |
3519 | return -1; |
3520 | } |
3521 | |
3522 | static inline void free_chain_hlocks(int base, int size) |
3523 | { |
3524 | add_chain_block(offset: base, max(size, 2)); |
3525 | } |
3526 | |
3527 | struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i) |
3528 | { |
3529 | u16 chain_hlock = chain_hlocks[chain->base + i]; |
3530 | unsigned int class_idx = chain_hlock_class_idx(hlock_id: chain_hlock); |
3531 | |
3532 | return lock_classes + class_idx; |
3533 | } |
3534 | |
3535 | /* |
3536 | * Returns the index of the first held_lock of the current chain |
3537 | */ |
3538 | static inline int get_first_held_lock(struct task_struct *curr, |
3539 | struct held_lock *hlock) |
3540 | { |
3541 | int i; |
3542 | struct held_lock *hlock_curr; |
3543 | |
3544 | for (i = curr->lockdep_depth - 1; i >= 0; i--) { |
3545 | hlock_curr = curr->held_locks + i; |
3546 | if (hlock_curr->irq_context != hlock->irq_context) |
3547 | break; |
3548 | |
3549 | } |
3550 | |
3551 | return ++i; |
3552 | } |
3553 | |
3554 | #ifdef CONFIG_DEBUG_LOCKDEP |
3555 | /* |
3556 | * Returns the next chain_key iteration |
3557 | */ |
3558 | static u64 print_chain_key_iteration(u16 hlock_id, u64 chain_key) |
3559 | { |
3560 | u64 new_chain_key = iterate_chain_key(key: chain_key, idx: hlock_id); |
3561 | |
3562 | printk(" hlock_id:%d -> chain_key:%016Lx" , |
3563 | (unsigned int)hlock_id, |
3564 | (unsigned long long)new_chain_key); |
3565 | return new_chain_key; |
3566 | } |
3567 | |
3568 | static void |
3569 | print_chain_keys_held_locks(struct task_struct *curr, struct held_lock *hlock_next) |
3570 | { |
3571 | struct held_lock *hlock; |
3572 | u64 chain_key = INITIAL_CHAIN_KEY; |
3573 | int depth = curr->lockdep_depth; |
3574 | int i = get_first_held_lock(curr, hlock: hlock_next); |
3575 | |
3576 | printk("depth: %u (irq_context %u)\n" , depth - i + 1, |
3577 | hlock_next->irq_context); |
3578 | for (; i < depth; i++) { |
3579 | hlock = curr->held_locks + i; |
3580 | chain_key = print_chain_key_iteration(hlock_id: hlock_id(hlock), chain_key); |
3581 | |
3582 | print_lock(hlock); |
3583 | } |
3584 | |
3585 | print_chain_key_iteration(hlock_id: hlock_id(hlock: hlock_next), chain_key); |
3586 | print_lock(hlock: hlock_next); |
3587 | } |
3588 | |
3589 | static void print_chain_keys_chain(struct lock_chain *chain) |
3590 | { |
3591 | int i; |
3592 | u64 chain_key = INITIAL_CHAIN_KEY; |
3593 | u16 hlock_id; |
3594 | |
3595 | printk("depth: %u\n" , chain->depth); |
3596 | for (i = 0; i < chain->depth; i++) { |
3597 | hlock_id = chain_hlocks[chain->base + i]; |
3598 | chain_key = print_chain_key_iteration(hlock_id, chain_key); |
3599 | |
3600 | print_lock_name(NULL, class: lock_classes + chain_hlock_class_idx(hlock_id)); |
3601 | printk("\n" ); |
3602 | } |
3603 | } |
3604 | |
3605 | static void print_collision(struct task_struct *curr, |
3606 | struct held_lock *hlock_next, |
3607 | struct lock_chain *chain) |
3608 | { |
3609 | pr_warn("\n" ); |
3610 | pr_warn("============================\n" ); |
3611 | pr_warn("WARNING: chain_key collision\n" ); |
3612 | print_kernel_ident(); |
3613 | pr_warn("----------------------------\n" ); |
3614 | pr_warn("%s/%d: " , current->comm, task_pid_nr(current)); |
3615 | pr_warn("Hash chain already cached but the contents don't match!\n" ); |
3616 | |
3617 | pr_warn("Held locks:" ); |
3618 | print_chain_keys_held_locks(curr, hlock_next); |
3619 | |
3620 | pr_warn("Locks in cached chain:" ); |
3621 | print_chain_keys_chain(chain); |
3622 | |
3623 | pr_warn("\nstack backtrace:\n" ); |
3624 | dump_stack(); |
3625 | } |
3626 | #endif |
3627 | |
3628 | /* |
3629 | * Checks whether the chain and the current held locks are consistent |
3630 | * in depth and also in content. If they are not it most likely means |
3631 | * that there was a collision during the calculation of the chain_key. |
3632 | * Returns: 0 not passed, 1 passed |
3633 | */ |
3634 | static int check_no_collision(struct task_struct *curr, |
3635 | struct held_lock *hlock, |
3636 | struct lock_chain *chain) |
3637 | { |
3638 | #ifdef CONFIG_DEBUG_LOCKDEP |
3639 | int i, j, id; |
3640 | |
3641 | i = get_first_held_lock(curr, hlock); |
3642 | |
3643 | if (DEBUG_LOCKS_WARN_ON(chain->depth != curr->lockdep_depth - (i - 1))) { |
3644 | print_collision(curr, hlock_next: hlock, chain); |
3645 | return 0; |
3646 | } |
3647 | |
3648 | for (j = 0; j < chain->depth - 1; j++, i++) { |
3649 | id = hlock_id(hlock: &curr->held_locks[i]); |
3650 | |
3651 | if (DEBUG_LOCKS_WARN_ON(chain_hlocks[chain->base + j] != id)) { |
3652 | print_collision(curr, hlock_next: hlock, chain); |
3653 | return 0; |
3654 | } |
3655 | } |
3656 | #endif |
3657 | return 1; |
3658 | } |
3659 | |
3660 | /* |
3661 | * Given an index that is >= -1, return the index of the next lock chain. |
3662 | * Return -2 if there is no next lock chain. |
3663 | */ |
3664 | long lockdep_next_lockchain(long i) |
3665 | { |
3666 | i = find_next_bit(addr: lock_chains_in_use, ARRAY_SIZE(lock_chains), offset: i + 1); |
3667 | return i < ARRAY_SIZE(lock_chains) ? i : -2; |
3668 | } |
3669 | |
3670 | unsigned long lock_chain_count(void) |
3671 | { |
3672 | return bitmap_weight(src: lock_chains_in_use, ARRAY_SIZE(lock_chains)); |
3673 | } |
3674 | |
3675 | /* Must be called with the graph lock held. */ |
3676 | static struct lock_chain *alloc_lock_chain(void) |
3677 | { |
3678 | int idx = find_first_zero_bit(addr: lock_chains_in_use, |
3679 | ARRAY_SIZE(lock_chains)); |
3680 | |
3681 | if (unlikely(idx >= ARRAY_SIZE(lock_chains))) |
3682 | return NULL; |
3683 | __set_bit(idx, lock_chains_in_use); |
3684 | return lock_chains + idx; |
3685 | } |
3686 | |
3687 | /* |
3688 | * Adds a dependency chain into chain hashtable. And must be called with |
3689 | * graph_lock held. |
3690 | * |
3691 | * Return 0 if fail, and graph_lock is released. |
3692 | * Return 1 if succeed, with graph_lock held. |
3693 | */ |
3694 | static inline int add_chain_cache(struct task_struct *curr, |
3695 | struct held_lock *hlock, |
3696 | u64 chain_key) |
3697 | { |
3698 | struct hlist_head *hash_head = chainhashentry(chain_key); |
3699 | struct lock_chain *chain; |
3700 | int i, j; |
3701 | |
3702 | /* |
3703 | * The caller must hold the graph lock, ensure we've got IRQs |
3704 | * disabled to make this an IRQ-safe lock.. for recursion reasons |
3705 | * lockdep won't complain about its own locking errors. |
3706 | */ |
3707 | if (lockdep_assert_locked()) |
3708 | return 0; |
3709 | |
3710 | chain = alloc_lock_chain(); |
3711 | if (!chain) { |
3712 | if (!debug_locks_off_graph_unlock()) |
3713 | return 0; |
3714 | |
3715 | print_lockdep_off(bug_msg: "BUG: MAX_LOCKDEP_CHAINS too low!" ); |
3716 | dump_stack(); |
3717 | return 0; |
3718 | } |
3719 | chain->chain_key = chain_key; |
3720 | chain->irq_context = hlock->irq_context; |
3721 | i = get_first_held_lock(curr, hlock); |
3722 | chain->depth = curr->lockdep_depth + 1 - i; |
3723 | |
3724 | BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks)); |
3725 | BUILD_BUG_ON((1UL << 6) <= ARRAY_SIZE(curr->held_locks)); |
3726 | BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks[0])) <= ARRAY_SIZE(lock_classes)); |
3727 | |
3728 | j = alloc_chain_hlocks(req: chain->depth); |
3729 | if (j < 0) { |
3730 | if (!debug_locks_off_graph_unlock()) |
3731 | return 0; |
3732 | |
3733 | print_lockdep_off(bug_msg: "BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!" ); |
3734 | dump_stack(); |
3735 | return 0; |
3736 | } |
3737 | |
3738 | chain->base = j; |
3739 | for (j = 0; j < chain->depth - 1; j++, i++) { |
3740 | int lock_id = hlock_id(hlock: curr->held_locks + i); |
3741 | |
3742 | chain_hlocks[chain->base + j] = lock_id; |
3743 | } |
3744 | chain_hlocks[chain->base + j] = hlock_id(hlock); |
3745 | hlist_add_head_rcu(n: &chain->entry, h: hash_head); |
3746 | debug_atomic_inc(chain_lookup_misses); |
3747 | inc_chains(irq_context: chain->irq_context); |
3748 | |
3749 | return 1; |
3750 | } |
3751 | |
3752 | /* |
3753 | * Look up a dependency chain. Must be called with either the graph lock or |
3754 | * the RCU read lock held. |
3755 | */ |
3756 | static inline struct lock_chain *lookup_chain_cache(u64 chain_key) |
3757 | { |
3758 | struct hlist_head *hash_head = chainhashentry(chain_key); |
3759 | struct lock_chain *chain; |
3760 | |
3761 | hlist_for_each_entry_rcu(chain, hash_head, entry) { |
3762 | if (READ_ONCE(chain->chain_key) == chain_key) { |
3763 | debug_atomic_inc(chain_lookup_hits); |
3764 | return chain; |
3765 | } |
3766 | } |
3767 | return NULL; |
3768 | } |
3769 | |
3770 | /* |
3771 | * If the key is not present yet in dependency chain cache then |
3772 | * add it and return 1 - in this case the new dependency chain is |
3773 | * validated. If the key is already hashed, return 0. |
3774 | * (On return with 1 graph_lock is held.) |
3775 | */ |
3776 | static inline int lookup_chain_cache_add(struct task_struct *curr, |
3777 | struct held_lock *hlock, |
3778 | u64 chain_key) |
3779 | { |
3780 | struct lock_class *class = hlock_class(hlock); |
3781 | struct lock_chain *chain = lookup_chain_cache(chain_key); |
3782 | |
3783 | if (chain) { |
3784 | cache_hit: |
3785 | if (!check_no_collision(curr, hlock, chain)) |
3786 | return 0; |
3787 | |
3788 | if (very_verbose(class)) { |
3789 | printk("\nhash chain already cached, key: " |
3790 | "%016Lx tail class: [%px] %s\n" , |
3791 | (unsigned long long)chain_key, |
3792 | class->key, class->name); |
3793 | } |
3794 | |
3795 | return 0; |
3796 | } |
3797 | |
3798 | if (very_verbose(class)) { |
3799 | printk("\nnew hash chain, key: %016Lx tail class: [%px] %s\n" , |
3800 | (unsigned long long)chain_key, class->key, class->name); |
3801 | } |
3802 | |
3803 | if (!graph_lock()) |
3804 | return 0; |
3805 | |
3806 | /* |
3807 | * We have to walk the chain again locked - to avoid duplicates: |
3808 | */ |
3809 | chain = lookup_chain_cache(chain_key); |
3810 | if (chain) { |
3811 | graph_unlock(); |
3812 | goto cache_hit; |
3813 | } |
3814 | |
3815 | if (!add_chain_cache(curr, hlock, chain_key)) |
3816 | return 0; |
3817 | |
3818 | return 1; |
3819 | } |
3820 | |
3821 | static int validate_chain(struct task_struct *curr, |
3822 | struct held_lock *hlock, |
3823 | int chain_head, u64 chain_key) |
3824 | { |
3825 | /* |
3826 | * Trylock needs to maintain the stack of held locks, but it |
3827 | * does not add new dependencies, because trylock can be done |
3828 | * in any order. |
3829 | * |
3830 | * We look up the chain_key and do the O(N^2) check and update of |
3831 | * the dependencies only if this is a new dependency chain. |
3832 | * (If lookup_chain_cache_add() return with 1 it acquires |
3833 | * graph_lock for us) |
3834 | */ |
3835 | if (!hlock->trylock && hlock->check && |
3836 | lookup_chain_cache_add(curr, hlock, chain_key)) { |
3837 | /* |
3838 | * Check whether last held lock: |
3839 | * |
3840 | * - is irq-safe, if this lock is irq-unsafe |
3841 | * - is softirq-safe, if this lock is hardirq-unsafe |
3842 | * |
3843 | * And check whether the new lock's dependency graph |
3844 | * could lead back to the previous lock: |
3845 | * |
3846 | * - within the current held-lock stack |
3847 | * - across our accumulated lock dependency records |
3848 | * |
3849 | * any of these scenarios could lead to a deadlock. |
3850 | */ |
3851 | /* |
3852 | * The simple case: does the current hold the same lock |
3853 | * already? |
3854 | */ |
3855 | int ret = check_deadlock(curr, next: hlock); |
3856 | |
3857 | if (!ret) |
3858 | return 0; |
3859 | /* |
3860 | * Add dependency only if this lock is not the head |
3861 | * of the chain, and if the new lock introduces no more |
3862 | * lock dependency (because we already hold a lock with the |
3863 | * same lock class) nor deadlock (because the nest_lock |
3864 | * serializes nesting locks), see the comments for |
3865 | * check_deadlock(). |
3866 | */ |
3867 | if (!chain_head && ret != 2) { |
3868 | if (!check_prevs_add(curr, next: hlock)) |
3869 | return 0; |
3870 | } |
3871 | |
3872 | graph_unlock(); |
3873 | } else { |
3874 | /* after lookup_chain_cache_add(): */ |
3875 | if (unlikely(!debug_locks)) |
3876 | return 0; |
3877 | } |
3878 | |
3879 | return 1; |
3880 | } |
3881 | #else |
3882 | static inline int validate_chain(struct task_struct *curr, |
3883 | struct held_lock *hlock, |
3884 | int chain_head, u64 chain_key) |
3885 | { |
3886 | return 1; |
3887 | } |
3888 | |
3889 | static void init_chain_block_buckets(void) { } |
3890 | #endif /* CONFIG_PROVE_LOCKING */ |
3891 | |
3892 | /* |
3893 | * We are building curr_chain_key incrementally, so double-check |
3894 | * it from scratch, to make sure that it's done correctly: |
3895 | */ |
3896 | static void check_chain_key(struct task_struct *curr) |
3897 | { |
3898 | #ifdef CONFIG_DEBUG_LOCKDEP |
3899 | struct held_lock *hlock, *prev_hlock = NULL; |
3900 | unsigned int i; |
3901 | u64 chain_key = INITIAL_CHAIN_KEY; |
3902 | |
3903 | for (i = 0; i < curr->lockdep_depth; i++) { |
3904 | hlock = curr->held_locks + i; |
3905 | if (chain_key != hlock->prev_chain_key) { |
3906 | debug_locks_off(); |
3907 | /* |
3908 | * We got mighty confused, our chain keys don't match |
3909 | * with what we expect, someone trample on our task state? |
3910 | */ |
3911 | WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n" , |
3912 | curr->lockdep_depth, i, |
3913 | (unsigned long long)chain_key, |
3914 | (unsigned long long)hlock->prev_chain_key); |
3915 | return; |
3916 | } |
3917 | |
3918 | /* |
3919 | * hlock->class_idx can't go beyond MAX_LOCKDEP_KEYS, but is |
3920 | * it registered lock class index? |
3921 | */ |
3922 | if (DEBUG_LOCKS_WARN_ON(!test_bit(hlock->class_idx, lock_classes_in_use))) |
3923 | return; |
3924 | |
3925 | if (prev_hlock && (prev_hlock->irq_context != |
3926 | hlock->irq_context)) |
3927 | chain_key = INITIAL_CHAIN_KEY; |
3928 | chain_key = iterate_chain_key(key: chain_key, idx: hlock_id(hlock)); |
3929 | prev_hlock = hlock; |
3930 | } |
3931 | if (chain_key != curr->curr_chain_key) { |
3932 | debug_locks_off(); |
3933 | /* |
3934 | * More smoking hash instead of calculating it, damn see these |
3935 | * numbers float.. I bet that a pink elephant stepped on my memory. |
3936 | */ |
3937 | WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n" , |
3938 | curr->lockdep_depth, i, |
3939 | (unsigned long long)chain_key, |
3940 | (unsigned long long)curr->curr_chain_key); |
3941 | } |
3942 | #endif |
3943 | } |
3944 | |
3945 | #ifdef CONFIG_PROVE_LOCKING |
3946 | static int mark_lock(struct task_struct *curr, struct held_lock *this, |
3947 | enum lock_usage_bit new_bit); |
3948 | |
3949 | static void print_usage_bug_scenario(struct held_lock *lock) |
3950 | { |
3951 | struct lock_class *class = hlock_class(hlock: lock); |
3952 | |
3953 | printk(" Possible unsafe locking scenario:\n\n" ); |
3954 | printk(" CPU0\n" ); |
3955 | printk(" ----\n" ); |
3956 | printk(" lock(" ); |
3957 | __print_lock_name(hlock: lock, class); |
3958 | printk(KERN_CONT ");\n" ); |
3959 | printk(" <Interrupt>\n" ); |
3960 | printk(" lock(" ); |
3961 | __print_lock_name(hlock: lock, class); |
3962 | printk(KERN_CONT ");\n" ); |
3963 | printk("\n *** DEADLOCK ***\n\n" ); |
3964 | } |
3965 | |
3966 | static void |
3967 | print_usage_bug(struct task_struct *curr, struct held_lock *this, |
3968 | enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit) |
3969 | { |
3970 | if (!debug_locks_off() || debug_locks_silent) |
3971 | return; |
3972 | |
3973 | pr_warn("\n" ); |
3974 | pr_warn("================================\n" ); |
3975 | pr_warn("WARNING: inconsistent lock state\n" ); |
3976 | print_kernel_ident(); |
3977 | pr_warn("--------------------------------\n" ); |
3978 | |
3979 | pr_warn("inconsistent {%s} -> {%s} usage.\n" , |
3980 | usage_str[prev_bit], usage_str[new_bit]); |
3981 | |
3982 | pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n" , |
3983 | curr->comm, task_pid_nr(curr), |
3984 | lockdep_hardirq_context(), hardirq_count() >> HARDIRQ_SHIFT, |
3985 | lockdep_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT, |
3986 | lockdep_hardirqs_enabled(), |
3987 | lockdep_softirqs_enabled(curr)); |
3988 | print_lock(hlock: this); |
3989 | |
3990 | pr_warn("{%s} state was registered at:\n" , usage_str[prev_bit]); |
3991 | print_lock_trace(trace: hlock_class(hlock: this)->usage_traces[prev_bit], spaces: 1); |
3992 | |
3993 | print_irqtrace_events(curr); |
3994 | pr_warn("\nother info that might help us debug this:\n" ); |
3995 | print_usage_bug_scenario(lock: this); |
3996 | |
3997 | lockdep_print_held_locks(p: curr); |
3998 | |
3999 | pr_warn("\nstack backtrace:\n" ); |
4000 | dump_stack(); |
4001 | } |
4002 | |
4003 | /* |
4004 | * Print out an error if an invalid bit is set: |
4005 | */ |
4006 | static inline int |
4007 | valid_state(struct task_struct *curr, struct held_lock *this, |
4008 | enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit) |
4009 | { |
4010 | if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit))) { |
4011 | graph_unlock(); |
4012 | print_usage_bug(curr, this, prev_bit: bad_bit, new_bit); |
4013 | return 0; |
4014 | } |
4015 | return 1; |
4016 | } |
4017 | |
4018 | |
4019 | /* |
4020 | * print irq inversion bug: |
4021 | */ |
4022 | static void |
4023 | print_irq_inversion_bug(struct task_struct *curr, |
4024 | struct lock_list *root, struct lock_list *other, |
4025 | struct held_lock *this, int forwards, |
4026 | const char *irqclass) |
4027 | { |
4028 | struct lock_list *entry = other; |
4029 | struct lock_list *middle = NULL; |
4030 | int depth; |
4031 | |
4032 | if (!debug_locks_off_graph_unlock() || debug_locks_silent) |
4033 | return; |
4034 | |
4035 | pr_warn("\n" ); |
4036 | pr_warn("========================================================\n" ); |
4037 | pr_warn("WARNING: possible irq lock inversion dependency detected\n" ); |
4038 | print_kernel_ident(); |
4039 | pr_warn("--------------------------------------------------------\n" ); |
4040 | pr_warn("%s/%d just changed the state of lock:\n" , |
4041 | curr->comm, task_pid_nr(curr)); |
4042 | print_lock(hlock: this); |
4043 | if (forwards) |
4044 | pr_warn("but this lock took another, %s-unsafe lock in the past:\n" , irqclass); |
4045 | else |
4046 | pr_warn("but this lock was taken by another, %s-safe lock in the past:\n" , irqclass); |
4047 | print_lock_name(NULL, class: other->class); |
4048 | pr_warn("\n\nand interrupts could create inverse lock ordering between them.\n\n" ); |
4049 | |
4050 | pr_warn("\nother info that might help us debug this:\n" ); |
4051 | |
4052 | /* Find a middle lock (if one exists) */ |
4053 | depth = get_lock_depth(child: other); |
4054 | do { |
4055 | if (depth == 0 && (entry != root)) { |
4056 | pr_warn("lockdep:%s bad path found in chain graph\n" , __func__); |
4057 | break; |
4058 | } |
4059 | middle = entry; |
4060 | entry = get_lock_parent(child: entry); |
4061 | depth--; |
4062 | } while (entry && entry != root && (depth >= 0)); |
4063 | if (forwards) |
4064 | print_irq_lock_scenario(safe_entry: root, unsafe_entry: other, |
4065 | prev_class: middle ? middle->class : root->class, next_class: other->class); |
4066 | else |
4067 | print_irq_lock_scenario(safe_entry: other, unsafe_entry: root, |
4068 | prev_class: middle ? middle->class : other->class, next_class: root->class); |
4069 | |
4070 | lockdep_print_held_locks(p: curr); |
4071 | |
4072 | pr_warn("\nthe shortest dependencies between 2nd lock and 1st lock:\n" ); |
4073 | root->trace = save_trace(); |
4074 | if (!root->trace) |
4075 | return; |
4076 | print_shortest_lock_dependencies(leaf: other, root); |
4077 | |
4078 | pr_warn("\nstack backtrace:\n" ); |
4079 | dump_stack(); |
4080 | } |
4081 | |
4082 | /* |
4083 | * Prove that in the forwards-direction subgraph starting at <this> |
4084 | * there is no lock matching <mask>: |
4085 | */ |
4086 | static int |
4087 | check_usage_forwards(struct task_struct *curr, struct held_lock *this, |
4088 | enum lock_usage_bit bit) |
4089 | { |
4090 | enum bfs_result ret; |
4091 | struct lock_list root; |
4092 | struct lock_list *target_entry; |
4093 | enum lock_usage_bit read_bit = bit + LOCK_USAGE_READ_MASK; |
4094 | unsigned usage_mask = lock_flag(bit) | lock_flag(bit: read_bit); |
4095 | |
4096 | bfs_init_root(lock: &root, hlock: this); |
4097 | ret = find_usage_forwards(root: &root, usage_mask, target_entry: &target_entry); |
4098 | if (bfs_error(res: ret)) { |
4099 | print_bfs_bug(ret); |
4100 | return 0; |
4101 | } |
4102 | if (ret == BFS_RNOMATCH) |
4103 | return 1; |
4104 | |
4105 | /* Check whether write or read usage is the match */ |
4106 | if (target_entry->class->usage_mask & lock_flag(bit)) { |
4107 | print_irq_inversion_bug(curr, root: &root, other: target_entry, |
4108 | this, forwards: 1, irqclass: state_name(bit)); |
4109 | } else { |
4110 | print_irq_inversion_bug(curr, root: &root, other: target_entry, |
4111 | this, forwards: 1, irqclass: state_name(bit: read_bit)); |
4112 | } |
4113 | |
4114 | return 0; |
4115 | } |
4116 | |
4117 | /* |
4118 | * Prove that in the backwards-direction subgraph starting at <this> |
4119 | * there is no lock matching <mask>: |
4120 | */ |
4121 | static int |
4122 | check_usage_backwards(struct task_struct *curr, struct held_lock *this, |
4123 | enum lock_usage_bit bit) |
4124 | { |
4125 | enum bfs_result ret; |
4126 | struct lock_list root; |
4127 | struct lock_list *target_entry; |
4128 | enum lock_usage_bit read_bit = bit + LOCK_USAGE_READ_MASK; |
4129 | unsigned usage_mask = lock_flag(bit) | lock_flag(bit: read_bit); |
4130 | |
4131 | bfs_init_rootb(lock: &root, hlock: this); |
4132 | ret = find_usage_backwards(root: &root, usage_mask, target_entry: &target_entry); |
4133 | if (bfs_error(res: ret)) { |
4134 | print_bfs_bug(ret); |
4135 | return 0; |
4136 | } |
4137 | if (ret == BFS_RNOMATCH) |
4138 | return 1; |
4139 | |
4140 | /* Check whether write or read usage is the match */ |
4141 | if (target_entry->class->usage_mask & lock_flag(bit)) { |
4142 | print_irq_inversion_bug(curr, root: &root, other: target_entry, |
4143 | this, forwards: 0, irqclass: state_name(bit)); |
4144 | } else { |
4145 | print_irq_inversion_bug(curr, root: &root, other: target_entry, |
4146 | this, forwards: 0, irqclass: state_name(bit: read_bit)); |
4147 | } |
4148 | |
4149 | return 0; |
4150 | } |
4151 | |
4152 | void print_irqtrace_events(struct task_struct *curr) |
4153 | { |
4154 | const struct irqtrace_events *trace = &curr->irqtrace; |
4155 | |
4156 | printk("irq event stamp: %u\n" , trace->irq_events); |
4157 | printk("hardirqs last enabled at (%u): [<%px>] %pS\n" , |
4158 | trace->hardirq_enable_event, (void *)trace->hardirq_enable_ip, |
4159 | (void *)trace->hardirq_enable_ip); |
4160 | printk("hardirqs last disabled at (%u): [<%px>] %pS\n" , |
4161 | trace->hardirq_disable_event, (void *)trace->hardirq_disable_ip, |
4162 | (void *)trace->hardirq_disable_ip); |
4163 | printk("softirqs last enabled at (%u): [<%px>] %pS\n" , |
4164 | trace->softirq_enable_event, (void *)trace->softirq_enable_ip, |
4165 | (void *)trace->softirq_enable_ip); |
4166 | printk("softirqs last disabled at (%u): [<%px>] %pS\n" , |
4167 | trace->softirq_disable_event, (void *)trace->softirq_disable_ip, |
4168 | (void *)trace->softirq_disable_ip); |
4169 | } |
4170 | |
4171 | static int HARDIRQ_verbose(struct lock_class *class) |
4172 | { |
4173 | #if HARDIRQ_VERBOSE |
4174 | return class_filter(class); |
4175 | #endif |
4176 | return 0; |
4177 | } |
4178 | |
4179 | static int SOFTIRQ_verbose(struct lock_class *class) |
4180 | { |
4181 | #if SOFTIRQ_VERBOSE |
4182 | return class_filter(class); |
4183 | #endif |
4184 | return 0; |
4185 | } |
4186 | |
4187 | static int (*state_verbose_f[])(struct lock_class *class) = { |
4188 | #define LOCKDEP_STATE(__STATE) \ |
4189 | __STATE##_verbose, |
4190 | #include "lockdep_states.h" |
4191 | #undef LOCKDEP_STATE |
4192 | }; |
4193 | |
4194 | static inline int state_verbose(enum lock_usage_bit bit, |
4195 | struct lock_class *class) |
4196 | { |
4197 | return state_verbose_f[bit >> LOCK_USAGE_DIR_MASK](class); |
4198 | } |
4199 | |
4200 | typedef int (*check_usage_f)(struct task_struct *, struct held_lock *, |
4201 | enum lock_usage_bit bit, const char *name); |
4202 | |
4203 | static int |
4204 | mark_lock_irq(struct task_struct *curr, struct held_lock *this, |
4205 | enum lock_usage_bit new_bit) |
4206 | { |
4207 | int excl_bit = exclusive_bit(new_bit); |
4208 | int read = new_bit & LOCK_USAGE_READ_MASK; |
4209 | int dir = new_bit & LOCK_USAGE_DIR_MASK; |
4210 | |
4211 | /* |
4212 | * Validate that this particular lock does not have conflicting |
4213 | * usage states. |
4214 | */ |
4215 | if (!valid_state(curr, this, new_bit, bad_bit: excl_bit)) |
4216 | return 0; |
4217 | |
4218 | /* |
4219 | * Check for read in write conflicts |
4220 | */ |
4221 | if (!read && !valid_state(curr, this, new_bit, |
4222 | bad_bit: excl_bit + LOCK_USAGE_READ_MASK)) |
4223 | return 0; |
4224 | |
4225 | |
4226 | /* |
4227 | * Validate that the lock dependencies don't have conflicting usage |
4228 | * states. |
4229 | */ |
4230 | if (dir) { |
4231 | /* |
4232 | * mark ENABLED has to look backwards -- to ensure no dependee |
4233 | * has USED_IN state, which, again, would allow recursion deadlocks. |
4234 | */ |
4235 | if (!check_usage_backwards(curr, this, bit: excl_bit)) |
4236 | return 0; |
4237 | } else { |
4238 | /* |
4239 | * mark USED_IN has to look forwards -- to ensure no dependency |
4240 | * has ENABLED state, which would allow recursion deadlocks. |
4241 | */ |
4242 | if (!check_usage_forwards(curr, this, bit: excl_bit)) |
4243 | return 0; |
4244 | } |
4245 | |
4246 | if (state_verbose(bit: new_bit, class: hlock_class(hlock: this))) |
4247 | return 2; |
4248 | |
4249 | return 1; |
4250 | } |
4251 | |
4252 | /* |
4253 | * Mark all held locks with a usage bit: |
4254 | */ |
4255 | static int |
4256 | mark_held_locks(struct task_struct *curr, enum lock_usage_bit base_bit) |
4257 | { |
4258 | struct held_lock *hlock; |
4259 | int i; |
4260 | |
4261 | for (i = 0; i < curr->lockdep_depth; i++) { |
4262 | enum lock_usage_bit hlock_bit = base_bit; |
4263 | hlock = curr->held_locks + i; |
4264 | |
4265 | if (hlock->read) |
4266 | hlock_bit += LOCK_USAGE_READ_MASK; |
4267 | |
4268 | BUG_ON(hlock_bit >= LOCK_USAGE_STATES); |
4269 | |
4270 | if (!hlock->check) |
4271 | continue; |
4272 | |
4273 | if (!mark_lock(curr, this: hlock, new_bit: hlock_bit)) |
4274 | return 0; |
4275 | } |
4276 | |
4277 | return 1; |
4278 | } |
4279 | |
4280 | /* |
4281 | * Hardirqs will be enabled: |
4282 | */ |
4283 | static void __trace_hardirqs_on_caller(void) |
4284 | { |
4285 | struct task_struct *curr = current; |
4286 | |
4287 | /* |
4288 | * We are going to turn hardirqs on, so set the |
4289 | * usage bit for all held locks: |
4290 | */ |
4291 | if (!mark_held_locks(curr, base_bit: LOCK_ENABLED_HARDIRQ)) |
4292 | return; |
4293 | /* |
4294 | * If we have softirqs enabled, then set the usage |
4295 | * bit for all held locks. (disabled hardirqs prevented |
4296 | * this bit from being set before) |
4297 | */ |
4298 | if (curr->softirqs_enabled) |
4299 | mark_held_locks(curr, base_bit: LOCK_ENABLED_SOFTIRQ); |
4300 | } |
4301 | |
4302 | /** |
4303 | * lockdep_hardirqs_on_prepare - Prepare for enabling interrupts |
4304 | * |
4305 | * Invoked before a possible transition to RCU idle from exit to user or |
4306 | * guest mode. This ensures that all RCU operations are done before RCU |
4307 | * stops watching. After the RCU transition lockdep_hardirqs_on() has to be |
4308 | * invoked to set the final state. |
4309 | */ |
4310 | void lockdep_hardirqs_on_prepare(void) |
4311 | { |
4312 | if (unlikely(!debug_locks)) |
4313 | return; |
4314 | |
4315 | /* |
4316 | * NMIs do not (and cannot) track lock dependencies, nothing to do. |
4317 | */ |
4318 | if (unlikely(in_nmi())) |
4319 | return; |
4320 | |
4321 | if (unlikely(this_cpu_read(lockdep_recursion))) |
4322 | return; |
4323 | |
4324 | if (unlikely(lockdep_hardirqs_enabled())) { |
4325 | /* |
4326 | * Neither irq nor preemption are disabled here |
4327 | * so this is racy by nature but losing one hit |
4328 | * in a stat is not a big deal. |
4329 | */ |
4330 | __debug_atomic_inc(redundant_hardirqs_on); |
4331 | return; |
4332 | } |
4333 | |
4334 | /* |
4335 | * We're enabling irqs and according to our state above irqs weren't |
4336 | * already enabled, yet we find the hardware thinks they are in fact |
4337 | * enabled.. someone messed up their IRQ state tracing. |
4338 | */ |
4339 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
4340 | return; |
4341 | |
4342 | /* |
4343 | * See the fine text that goes along with this variable definition. |
4344 | */ |
4345 | if (DEBUG_LOCKS_WARN_ON(early_boot_irqs_disabled)) |
4346 | return; |
4347 | |
4348 | /* |
4349 | * Can't allow enabling interrupts while in an interrupt handler, |
4350 | * that's general bad form and such. Recursion, limited stack etc.. |
4351 | */ |
4352 | if (DEBUG_LOCKS_WARN_ON(lockdep_hardirq_context())) |
4353 | return; |
4354 | |
4355 | current->hardirq_chain_key = current->curr_chain_key; |
4356 | |
4357 | lockdep_recursion_inc(); |
4358 | __trace_hardirqs_on_caller(); |
4359 | lockdep_recursion_finish(); |
4360 | } |
4361 | EXPORT_SYMBOL_GPL(lockdep_hardirqs_on_prepare); |
4362 | |
4363 | void noinstr lockdep_hardirqs_on(unsigned long ip) |
4364 | { |
4365 | struct irqtrace_events *trace = ¤t->irqtrace; |
4366 | |
4367 | if (unlikely(!debug_locks)) |
4368 | return; |
4369 | |
4370 | /* |
4371 | * NMIs can happen in the middle of local_irq_{en,dis}able() where the |
4372 | * tracking state and hardware state are out of sync. |
4373 | * |
4374 | * NMIs must save lockdep_hardirqs_enabled() to restore IRQ state from, |
4375 | * and not rely on hardware state like normal interrupts. |
4376 | */ |
4377 | if (unlikely(in_nmi())) { |
4378 | if (!IS_ENABLED(CONFIG_TRACE_IRQFLAGS_NMI)) |
4379 | return; |
4380 | |
4381 | /* |
4382 | * Skip: |
4383 | * - recursion check, because NMI can hit lockdep; |
4384 | * - hardware state check, because above; |
4385 | * - chain_key check, see lockdep_hardirqs_on_prepare(). |
4386 | */ |
4387 | goto skip_checks; |
4388 | } |
4389 | |
4390 | if (unlikely(this_cpu_read(lockdep_recursion))) |
4391 | return; |
4392 | |
4393 | if (lockdep_hardirqs_enabled()) { |
4394 | /* |
4395 | * Neither irq nor preemption are disabled here |
4396 | * so this is racy by nature but losing one hit |
4397 | * in a stat is not a big deal. |
4398 | */ |
4399 | __debug_atomic_inc(redundant_hardirqs_on); |
4400 | return; |
4401 | } |
4402 | |
4403 | /* |
4404 | * We're enabling irqs and according to our state above irqs weren't |
4405 | * already enabled, yet we find the hardware thinks they are in fact |
4406 | * enabled.. someone messed up their IRQ state tracing. |
4407 | */ |
4408 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
4409 | return; |
4410 | |
4411 | /* |
4412 | * Ensure the lock stack remained unchanged between |
4413 | * lockdep_hardirqs_on_prepare() and lockdep_hardirqs_on(). |
4414 | */ |
4415 | DEBUG_LOCKS_WARN_ON(current->hardirq_chain_key != |
4416 | current->curr_chain_key); |
4417 | |
4418 | skip_checks: |
4419 | /* we'll do an OFF -> ON transition: */ |
4420 | __this_cpu_write(hardirqs_enabled, 1); |
4421 | trace->hardirq_enable_ip = ip; |
4422 | trace->hardirq_enable_event = ++trace->irq_events; |
4423 | debug_atomic_inc(hardirqs_on_events); |
4424 | } |
4425 | EXPORT_SYMBOL_GPL(lockdep_hardirqs_on); |
4426 | |
4427 | /* |
4428 | * Hardirqs were disabled: |
4429 | */ |
4430 | void noinstr lockdep_hardirqs_off(unsigned long ip) |
4431 | { |
4432 | if (unlikely(!debug_locks)) |
4433 | return; |
4434 | |
4435 | /* |
4436 | * Matching lockdep_hardirqs_on(), allow NMIs in the middle of lockdep; |
4437 | * they will restore the software state. This ensures the software |
4438 | * state is consistent inside NMIs as well. |
4439 | */ |
4440 | if (in_nmi()) { |
4441 | if (!IS_ENABLED(CONFIG_TRACE_IRQFLAGS_NMI)) |
4442 | return; |
4443 | } else if (__this_cpu_read(lockdep_recursion)) |
4444 | return; |
4445 | |
4446 | /* |
4447 | * So we're supposed to get called after you mask local IRQs, but for |
4448 | * some reason the hardware doesn't quite think you did a proper job. |
4449 | */ |
4450 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
4451 | return; |
4452 | |
4453 | if (lockdep_hardirqs_enabled()) { |
4454 | struct irqtrace_events *trace = ¤t->irqtrace; |
4455 | |
4456 | /* |
4457 | * We have done an ON -> OFF transition: |
4458 | */ |
4459 | __this_cpu_write(hardirqs_enabled, 0); |
4460 | trace->hardirq_disable_ip = ip; |
4461 | trace->hardirq_disable_event = ++trace->irq_events; |
4462 | debug_atomic_inc(hardirqs_off_events); |
4463 | } else { |
4464 | debug_atomic_inc(redundant_hardirqs_off); |
4465 | } |
4466 | } |
4467 | EXPORT_SYMBOL_GPL(lockdep_hardirqs_off); |
4468 | |
4469 | /* |
4470 | * Softirqs will be enabled: |
4471 | */ |
4472 | void lockdep_softirqs_on(unsigned long ip) |
4473 | { |
4474 | struct irqtrace_events *trace = ¤t->irqtrace; |
4475 | |
4476 | if (unlikely(!lockdep_enabled())) |
4477 | return; |
4478 | |
4479 | /* |
4480 | * We fancy IRQs being disabled here, see softirq.c, avoids |
4481 | * funny state and nesting things. |
4482 | */ |
4483 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
4484 | return; |
4485 | |
4486 | if (current->softirqs_enabled) { |
4487 | debug_atomic_inc(redundant_softirqs_on); |
4488 | return; |
4489 | } |
4490 | |
4491 | lockdep_recursion_inc(); |
4492 | /* |
4493 | * We'll do an OFF -> ON transition: |
4494 | */ |
4495 | current->softirqs_enabled = 1; |
4496 | trace->softirq_enable_ip = ip; |
4497 | trace->softirq_enable_event = ++trace->irq_events; |
4498 | debug_atomic_inc(softirqs_on_events); |
4499 | /* |
4500 | * We are going to turn softirqs on, so set the |
4501 | * usage bit for all held locks, if hardirqs are |
4502 | * enabled too: |
4503 | */ |
4504 | if (lockdep_hardirqs_enabled()) |
4505 | mark_held_locks(current, base_bit: LOCK_ENABLED_SOFTIRQ); |
4506 | lockdep_recursion_finish(); |
4507 | } |
4508 | |
4509 | /* |
4510 | * Softirqs were disabled: |
4511 | */ |
4512 | void lockdep_softirqs_off(unsigned long ip) |
4513 | { |
4514 | if (unlikely(!lockdep_enabled())) |
4515 | return; |
4516 | |
4517 | /* |
4518 | * We fancy IRQs being disabled here, see softirq.c |
4519 | */ |
4520 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
4521 | return; |
4522 | |
4523 | if (current->softirqs_enabled) { |
4524 | struct irqtrace_events *trace = ¤t->irqtrace; |
4525 | |
4526 | /* |
4527 | * We have done an ON -> OFF transition: |
4528 | */ |
4529 | current->softirqs_enabled = 0; |
4530 | trace->softirq_disable_ip = ip; |
4531 | trace->softirq_disable_event = ++trace->irq_events; |
4532 | debug_atomic_inc(softirqs_off_events); |
4533 | /* |
4534 | * Whoops, we wanted softirqs off, so why aren't they? |
4535 | */ |
4536 | DEBUG_LOCKS_WARN_ON(!softirq_count()); |
4537 | } else |
4538 | debug_atomic_inc(redundant_softirqs_off); |
4539 | } |
4540 | |
4541 | static int |
4542 | mark_usage(struct task_struct *curr, struct held_lock *hlock, int check) |
4543 | { |
4544 | if (!check) |
4545 | goto lock_used; |
4546 | |
4547 | /* |
4548 | * If non-trylock use in a hardirq or softirq context, then |
4549 | * mark the lock as used in these contexts: |
4550 | */ |
4551 | if (!hlock->trylock) { |
4552 | if (hlock->read) { |
4553 | if (lockdep_hardirq_context()) |
4554 | if (!mark_lock(curr, this: hlock, |
4555 | new_bit: LOCK_USED_IN_HARDIRQ_READ)) |
4556 | return 0; |
4557 | if (curr->softirq_context) |
4558 | if (!mark_lock(curr, this: hlock, |
4559 | new_bit: LOCK_USED_IN_SOFTIRQ_READ)) |
4560 | return 0; |
4561 | } else { |
4562 | if (lockdep_hardirq_context()) |
4563 | if (!mark_lock(curr, this: hlock, new_bit: LOCK_USED_IN_HARDIRQ)) |
4564 | return 0; |
4565 | if (curr->softirq_context) |
4566 | if (!mark_lock(curr, this: hlock, new_bit: LOCK_USED_IN_SOFTIRQ)) |
4567 | return 0; |
4568 | } |
4569 | } |
4570 | |
4571 | /* |
4572 | * For lock_sync(), don't mark the ENABLED usage, since lock_sync() |
4573 | * creates no critical section and no extra dependency can be introduced |
4574 | * by interrupts |
4575 | */ |
4576 | if (!hlock->hardirqs_off && !hlock->sync) { |
4577 | if (hlock->read) { |
4578 | if (!mark_lock(curr, this: hlock, |
4579 | new_bit: LOCK_ENABLED_HARDIRQ_READ)) |
4580 | return 0; |
4581 | if (curr->softirqs_enabled) |
4582 | if (!mark_lock(curr, this: hlock, |
4583 | new_bit: LOCK_ENABLED_SOFTIRQ_READ)) |
4584 | return 0; |
4585 | } else { |
4586 | if (!mark_lock(curr, this: hlock, |
4587 | new_bit: LOCK_ENABLED_HARDIRQ)) |
4588 | return 0; |
4589 | if (curr->softirqs_enabled) |
4590 | if (!mark_lock(curr, this: hlock, |
4591 | new_bit: LOCK_ENABLED_SOFTIRQ)) |
4592 | return 0; |
4593 | } |
4594 | } |
4595 | |
4596 | lock_used: |
4597 | /* mark it as used: */ |
4598 | if (!mark_lock(curr, this: hlock, new_bit: LOCK_USED)) |
4599 | return 0; |
4600 | |
4601 | return 1; |
4602 | } |
4603 | |
4604 | static inline unsigned int task_irq_context(struct task_struct *task) |
4605 | { |
4606 | return LOCK_CHAIN_HARDIRQ_CONTEXT * !!lockdep_hardirq_context() + |
4607 | LOCK_CHAIN_SOFTIRQ_CONTEXT * !!task->softirq_context; |
4608 | } |
4609 | |
4610 | static int separate_irq_context(struct task_struct *curr, |
4611 | struct held_lock *hlock) |
4612 | { |
4613 | unsigned int depth = curr->lockdep_depth; |
4614 | |
4615 | /* |
4616 | * Keep track of points where we cross into an interrupt context: |
4617 | */ |
4618 | if (depth) { |
4619 | struct held_lock *prev_hlock; |
4620 | |
4621 | prev_hlock = curr->held_locks + depth-1; |
4622 | /* |
4623 | * If we cross into another context, reset the |
4624 | * hash key (this also prevents the checking and the |
4625 | * adding of the dependency to 'prev'): |
4626 | */ |
4627 | if (prev_hlock->irq_context != hlock->irq_context) |
4628 | return 1; |
4629 | } |
4630 | return 0; |
4631 | } |
4632 | |
4633 | /* |
4634 | * Mark a lock with a usage bit, and validate the state transition: |
4635 | */ |
4636 | static int mark_lock(struct task_struct *curr, struct held_lock *this, |
4637 | enum lock_usage_bit new_bit) |
4638 | { |
4639 | unsigned int new_mask, ret = 1; |
4640 | |
4641 | if (new_bit >= LOCK_USAGE_STATES) { |
4642 | DEBUG_LOCKS_WARN_ON(1); |
4643 | return 0; |
4644 | } |
4645 | |
4646 | if (new_bit == LOCK_USED && this->read) |
4647 | new_bit = LOCK_USED_READ; |
4648 | |
4649 | new_mask = 1 << new_bit; |
4650 | |
4651 | /* |
4652 | * If already set then do not dirty the cacheline, |
4653 | * nor do any checks: |
4654 | */ |
4655 | if (likely(hlock_class(this)->usage_mask & new_mask)) |
4656 | return 1; |
4657 | |
4658 | if (!graph_lock()) |
4659 | return 0; |
4660 | /* |
4661 | * Make sure we didn't race: |
4662 | */ |
4663 | if (unlikely(hlock_class(this)->usage_mask & new_mask)) |
4664 | goto unlock; |
4665 | |
4666 | if (!hlock_class(hlock: this)->usage_mask) |
4667 | debug_atomic_dec(nr_unused_locks); |
4668 | |
4669 | hlock_class(hlock: this)->usage_mask |= new_mask; |
4670 | |
4671 | if (new_bit < LOCK_TRACE_STATES) { |
4672 | if (!(hlock_class(hlock: this)->usage_traces[new_bit] = save_trace())) |
4673 | return 0; |
4674 | } |
4675 | |
4676 | if (new_bit < LOCK_USED) { |
4677 | ret = mark_lock_irq(curr, this, new_bit); |
4678 | if (!ret) |
4679 | return 0; |
4680 | } |
4681 | |
4682 | unlock: |
4683 | graph_unlock(); |
4684 | |
4685 | /* |
4686 | * We must printk outside of the graph_lock: |
4687 | */ |
4688 | if (ret == 2) { |
4689 | printk("\nmarked lock as {%s}:\n" , usage_str[new_bit]); |
4690 | print_lock(hlock: this); |
4691 | print_irqtrace_events(curr); |
4692 | dump_stack(); |
4693 | } |
4694 | |
4695 | return ret; |
4696 | } |
4697 | |
4698 | static inline short task_wait_context(struct task_struct *curr) |
4699 | { |
4700 | /* |
4701 | * Set appropriate wait type for the context; for IRQs we have to take |
4702 | * into account force_irqthread as that is implied by PREEMPT_RT. |
4703 | */ |
4704 | if (lockdep_hardirq_context()) { |
4705 | /* |
4706 | * Check if force_irqthreads will run us threaded. |
4707 | */ |
4708 | if (curr->hardirq_threaded || curr->irq_config) |
4709 | return LD_WAIT_CONFIG; |
4710 | |
4711 | return LD_WAIT_SPIN; |
4712 | } else if (curr->softirq_context) { |
4713 | /* |
4714 | * Softirqs are always threaded. |
4715 | */ |
4716 | return LD_WAIT_CONFIG; |
4717 | } |
4718 | |
4719 | return LD_WAIT_MAX; |
4720 | } |
4721 | |
4722 | static int |
4723 | print_lock_invalid_wait_context(struct task_struct *curr, |
4724 | struct held_lock *hlock) |
4725 | { |
4726 | short curr_inner; |
4727 | |
4728 | if (!debug_locks_off()) |
4729 | return 0; |
4730 | if (debug_locks_silent) |
4731 | return 0; |
4732 | |
4733 | pr_warn("\n" ); |
4734 | pr_warn("=============================\n" ); |
4735 | pr_warn("[ BUG: Invalid wait context ]\n" ); |
4736 | print_kernel_ident(); |
4737 | pr_warn("-----------------------------\n" ); |
4738 | |
4739 | pr_warn("%s/%d is trying to lock:\n" , curr->comm, task_pid_nr(curr)); |
4740 | print_lock(hlock); |
4741 | |
4742 | pr_warn("other info that might help us debug this:\n" ); |
4743 | |
4744 | curr_inner = task_wait_context(curr); |
4745 | pr_warn("context-{%d:%d}\n" , curr_inner, curr_inner); |
4746 | |
4747 | lockdep_print_held_locks(p: curr); |
4748 | |
4749 | pr_warn("stack backtrace:\n" ); |
4750 | dump_stack(); |
4751 | |
4752 | return 0; |
4753 | } |
4754 | |
4755 | /* |
4756 | * Verify the wait_type context. |
4757 | * |
4758 | * This check validates we take locks in the right wait-type order; that is it |
4759 | * ensures that we do not take mutexes inside spinlocks and do not attempt to |
4760 | * acquire spinlocks inside raw_spinlocks and the sort. |
4761 | * |
4762 | * The entire thing is slightly more complex because of RCU, RCU is a lock that |
4763 | * can be taken from (pretty much) any context but also has constraints. |
4764 | * However when taken in a stricter environment the RCU lock does not loosen |
4765 | * the constraints. |
4766 | * |
4767 | * Therefore we must look for the strictest environment in the lock stack and |
4768 | * compare that to the lock we're trying to acquire. |
4769 | */ |
4770 | static int check_wait_context(struct task_struct *curr, struct held_lock *next) |
4771 | { |
4772 | u8 next_inner = hlock_class(hlock: next)->wait_type_inner; |
4773 | u8 next_outer = hlock_class(hlock: next)->wait_type_outer; |
4774 | u8 curr_inner; |
4775 | int depth; |
4776 | |
4777 | if (!next_inner || next->trylock) |
4778 | return 0; |
4779 | |
4780 | if (!next_outer) |
4781 | next_outer = next_inner; |
4782 | |
4783 | /* |
4784 | * Find start of current irq_context.. |
4785 | */ |
4786 | for (depth = curr->lockdep_depth - 1; depth >= 0; depth--) { |
4787 | struct held_lock *prev = curr->held_locks + depth; |
4788 | if (prev->irq_context != next->irq_context) |
4789 | break; |
4790 | } |
4791 | depth++; |
4792 | |
4793 | curr_inner = task_wait_context(curr); |
4794 | |
4795 | for (; depth < curr->lockdep_depth; depth++) { |
4796 | struct held_lock *prev = curr->held_locks + depth; |
4797 | struct lock_class *class = hlock_class(hlock: prev); |
4798 | u8 prev_inner = class->wait_type_inner; |
4799 | |
4800 | if (prev_inner) { |
4801 | /* |
4802 | * We can have a bigger inner than a previous one |
4803 | * when outer is smaller than inner, as with RCU. |
4804 | * |
4805 | * Also due to trylocks. |
4806 | */ |
4807 | curr_inner = min(curr_inner, prev_inner); |
4808 | |
4809 | /* |
4810 | * Allow override for annotations -- this is typically |
4811 | * only valid/needed for code that only exists when |
4812 | * CONFIG_PREEMPT_RT=n. |
4813 | */ |
4814 | if (unlikely(class->lock_type == LD_LOCK_WAIT_OVERRIDE)) |
4815 | curr_inner = prev_inner; |
4816 | } |
4817 | } |
4818 | |
4819 | if (next_outer > curr_inner) |
4820 | return print_lock_invalid_wait_context(curr, hlock: next); |
4821 | |
4822 | return 0; |
4823 | } |
4824 | |
4825 | #else /* CONFIG_PROVE_LOCKING */ |
4826 | |
4827 | static inline int |
4828 | mark_usage(struct task_struct *curr, struct held_lock *hlock, int check) |
4829 | { |
4830 | return 1; |
4831 | } |
4832 | |
4833 | static inline unsigned int task_irq_context(struct task_struct *task) |
4834 | { |
4835 | return 0; |
4836 | } |
4837 | |
4838 | static inline int separate_irq_context(struct task_struct *curr, |
4839 | struct held_lock *hlock) |
4840 | { |
4841 | return 0; |
4842 | } |
4843 | |
4844 | static inline int check_wait_context(struct task_struct *curr, |
4845 | struct held_lock *next) |
4846 | { |
4847 | return 0; |
4848 | } |
4849 | |
4850 | #endif /* CONFIG_PROVE_LOCKING */ |
4851 | |
4852 | /* |
4853 | * Initialize a lock instance's lock-class mapping info: |
4854 | */ |
4855 | void lockdep_init_map_type(struct lockdep_map *lock, const char *name, |
4856 | struct lock_class_key *key, int subclass, |
4857 | u8 inner, u8 outer, u8 lock_type) |
4858 | { |
4859 | int i; |
4860 | |
4861 | for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++) |
4862 | lock->class_cache[i] = NULL; |
4863 | |
4864 | #ifdef CONFIG_LOCK_STAT |
4865 | lock->cpu = raw_smp_processor_id(); |
4866 | #endif |
4867 | |
4868 | /* |
4869 | * Can't be having no nameless bastards around this place! |
4870 | */ |
4871 | if (DEBUG_LOCKS_WARN_ON(!name)) { |
4872 | lock->name = "NULL" ; |
4873 | return; |
4874 | } |
4875 | |
4876 | lock->name = name; |
4877 | |
4878 | lock->wait_type_outer = outer; |
4879 | lock->wait_type_inner = inner; |
4880 | lock->lock_type = lock_type; |
4881 | |
4882 | /* |
4883 | * No key, no joy, we need to hash something. |
4884 | */ |
4885 | if (DEBUG_LOCKS_WARN_ON(!key)) |
4886 | return; |
4887 | /* |
4888 | * Sanity check, the lock-class key must either have been allocated |
4889 | * statically or must have been registered as a dynamic key. |
4890 | */ |
4891 | if (!static_obj(obj: key) && !is_dynamic_key(key)) { |
4892 | if (debug_locks) |
4893 | printk(KERN_ERR "BUG: key %px has not been registered!\n" , key); |
4894 | DEBUG_LOCKS_WARN_ON(1); |
4895 | return; |
4896 | } |
4897 | lock->key = key; |
4898 | |
4899 | if (unlikely(!debug_locks)) |
4900 | return; |
4901 | |
4902 | if (subclass) { |
4903 | unsigned long flags; |
4904 | |
4905 | if (DEBUG_LOCKS_WARN_ON(!lockdep_enabled())) |
4906 | return; |
4907 | |
4908 | raw_local_irq_save(flags); |
4909 | lockdep_recursion_inc(); |
4910 | register_lock_class(lock, subclass, force: 1); |
4911 | lockdep_recursion_finish(); |
4912 | raw_local_irq_restore(flags); |
4913 | } |
4914 | } |
4915 | EXPORT_SYMBOL_GPL(lockdep_init_map_type); |
4916 | |
4917 | struct lock_class_key __lockdep_no_validate__; |
4918 | EXPORT_SYMBOL_GPL(__lockdep_no_validate__); |
4919 | |
4920 | #ifdef CONFIG_PROVE_LOCKING |
4921 | void lockdep_set_lock_cmp_fn(struct lockdep_map *lock, lock_cmp_fn cmp_fn, |
4922 | lock_print_fn print_fn) |
4923 | { |
4924 | struct lock_class *class = lock->class_cache[0]; |
4925 | unsigned long flags; |
4926 | |
4927 | raw_local_irq_save(flags); |
4928 | lockdep_recursion_inc(); |
4929 | |
4930 | if (!class) |
4931 | class = register_lock_class(lock, subclass: 0, force: 0); |
4932 | |
4933 | if (class) { |
4934 | WARN_ON(class->cmp_fn && class->cmp_fn != cmp_fn); |
4935 | WARN_ON(class->print_fn && class->print_fn != print_fn); |
4936 | |
4937 | class->cmp_fn = cmp_fn; |
4938 | class->print_fn = print_fn; |
4939 | } |
4940 | |
4941 | lockdep_recursion_finish(); |
4942 | raw_local_irq_restore(flags); |
4943 | } |
4944 | EXPORT_SYMBOL_GPL(lockdep_set_lock_cmp_fn); |
4945 | #endif |
4946 | |
4947 | static void |
4948 | print_lock_nested_lock_not_held(struct task_struct *curr, |
4949 | struct held_lock *hlock) |
4950 | { |
4951 | if (!debug_locks_off()) |
4952 | return; |
4953 | if (debug_locks_silent) |
4954 | return; |
4955 | |
4956 | pr_warn("\n" ); |
4957 | pr_warn("==================================\n" ); |
4958 | pr_warn("WARNING: Nested lock was not taken\n" ); |
4959 | print_kernel_ident(); |
4960 | pr_warn("----------------------------------\n" ); |
4961 | |
4962 | pr_warn("%s/%d is trying to lock:\n" , curr->comm, task_pid_nr(curr)); |
4963 | print_lock(hlock); |
4964 | |
4965 | pr_warn("\nbut this task is not holding:\n" ); |
4966 | pr_warn("%s\n" , hlock->nest_lock->name); |
4967 | |
4968 | pr_warn("\nstack backtrace:\n" ); |
4969 | dump_stack(); |
4970 | |
4971 | pr_warn("\nother info that might help us debug this:\n" ); |
4972 | lockdep_print_held_locks(p: curr); |
4973 | |
4974 | pr_warn("\nstack backtrace:\n" ); |
4975 | dump_stack(); |
4976 | } |
4977 | |
4978 | static int __lock_is_held(const struct lockdep_map *lock, int read); |
4979 | |
4980 | /* |
4981 | * This gets called for every mutex_lock*()/spin_lock*() operation. |
4982 | * We maintain the dependency maps and validate the locking attempt: |
4983 | * |
4984 | * The callers must make sure that IRQs are disabled before calling it, |
4985 | * otherwise we could get an interrupt which would want to take locks, |
4986 | * which would end up in lockdep again. |
4987 | */ |
4988 | static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, |
4989 | int trylock, int read, int check, int hardirqs_off, |
4990 | struct lockdep_map *nest_lock, unsigned long ip, |
4991 | int references, int pin_count, int sync) |
4992 | { |
4993 | struct task_struct *curr = current; |
4994 | struct lock_class *class = NULL; |
4995 | struct held_lock *hlock; |
4996 | unsigned int depth; |
4997 | int chain_head = 0; |
4998 | int class_idx; |
4999 | u64 chain_key; |
5000 | |
5001 | if (unlikely(!debug_locks)) |
5002 | return 0; |
5003 | |
5004 | if (!prove_locking || lock->key == &__lockdep_no_validate__) |
5005 | check = 0; |
5006 | |
5007 | if (subclass < NR_LOCKDEP_CACHING_CLASSES) |
5008 | class = lock->class_cache[subclass]; |
5009 | /* |
5010 | * Not cached? |
5011 | */ |
5012 | if (unlikely(!class)) { |
5013 | class = register_lock_class(lock, subclass, force: 0); |
5014 | if (!class) |
5015 | return 0; |
5016 | } |
5017 | |
5018 | debug_class_ops_inc(class); |
5019 | |
5020 | if (very_verbose(class)) { |
5021 | printk("\nacquire class [%px] %s" , class->key, class->name); |
5022 | if (class->name_version > 1) |
5023 | printk(KERN_CONT "#%d" , class->name_version); |
5024 | printk(KERN_CONT "\n" ); |
5025 | dump_stack(); |
5026 | } |
5027 | |
5028 | /* |
5029 | * Add the lock to the list of currently held locks. |
5030 | * (we dont increase the depth just yet, up until the |
5031 | * dependency checks are done) |
5032 | */ |
5033 | depth = curr->lockdep_depth; |
5034 | /* |
5035 | * Ran out of static storage for our per-task lock stack again have we? |
5036 | */ |
5037 | if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH)) |
5038 | return 0; |
5039 | |
5040 | class_idx = class - lock_classes; |
5041 | |
5042 | if (depth && !sync) { |
5043 | /* we're holding locks and the new held lock is not a sync */ |
5044 | hlock = curr->held_locks + depth - 1; |
5045 | if (hlock->class_idx == class_idx && nest_lock) { |
5046 | if (!references) |
5047 | references++; |
5048 | |
5049 | if (!hlock->references) |
5050 | hlock->references++; |
5051 | |
5052 | hlock->references += references; |
5053 | |
5054 | /* Overflow */ |
5055 | if (DEBUG_LOCKS_WARN_ON(hlock->references < references)) |
5056 | return 0; |
5057 | |
5058 | return 2; |
5059 | } |
5060 | } |
5061 | |
5062 | hlock = curr->held_locks + depth; |
5063 | /* |
5064 | * Plain impossible, we just registered it and checked it weren't no |
5065 | * NULL like.. I bet this mushroom I ate was good! |
5066 | */ |
5067 | if (DEBUG_LOCKS_WARN_ON(!class)) |
5068 | return 0; |
5069 | hlock->class_idx = class_idx; |
5070 | hlock->acquire_ip = ip; |
5071 | hlock->instance = lock; |
5072 | hlock->nest_lock = nest_lock; |
5073 | hlock->irq_context = task_irq_context(task: curr); |
5074 | hlock->trylock = trylock; |
5075 | hlock->read = read; |
5076 | hlock->check = check; |
5077 | hlock->sync = !!sync; |
5078 | hlock->hardirqs_off = !!hardirqs_off; |
5079 | hlock->references = references; |
5080 | #ifdef CONFIG_LOCK_STAT |
5081 | hlock->waittime_stamp = 0; |
5082 | hlock->holdtime_stamp = lockstat_clock(); |
5083 | #endif |
5084 | hlock->pin_count = pin_count; |
5085 | |
5086 | if (check_wait_context(curr, next: hlock)) |
5087 | return 0; |
5088 | |
5089 | /* Initialize the lock usage bit */ |
5090 | if (!mark_usage(curr, hlock, check)) |
5091 | return 0; |
5092 | |
5093 | /* |
5094 | * Calculate the chain hash: it's the combined hash of all the |
5095 | * lock keys along the dependency chain. We save the hash value |
5096 | * at every step so that we can get the current hash easily |
5097 | * after unlock. The chain hash is then used to cache dependency |
5098 | * results. |
5099 | * |
5100 | * The 'key ID' is what is the most compact key value to drive |
5101 | * the hash, not class->key. |
5102 | */ |
5103 | /* |
5104 | * Whoops, we did it again.. class_idx is invalid. |
5105 | */ |
5106 | if (DEBUG_LOCKS_WARN_ON(!test_bit(class_idx, lock_classes_in_use))) |
5107 | return 0; |
5108 | |
5109 | chain_key = curr->curr_chain_key; |
5110 | if (!depth) { |
5111 | /* |
5112 | * How can we have a chain hash when we ain't got no keys?! |
5113 | */ |
5114 | if (DEBUG_LOCKS_WARN_ON(chain_key != INITIAL_CHAIN_KEY)) |
5115 | return 0; |
5116 | chain_head = 1; |
5117 | } |
5118 | |
5119 | hlock->prev_chain_key = chain_key; |
5120 | if (separate_irq_context(curr, hlock)) { |
5121 | chain_key = INITIAL_CHAIN_KEY; |
5122 | chain_head = 1; |
5123 | } |
5124 | chain_key = iterate_chain_key(key: chain_key, idx: hlock_id(hlock)); |
5125 | |
5126 | if (nest_lock && !__lock_is_held(lock: nest_lock, read: -1)) { |
5127 | print_lock_nested_lock_not_held(curr, hlock); |
5128 | return 0; |
5129 | } |
5130 | |
5131 | if (!debug_locks_silent) { |
5132 | WARN_ON_ONCE(depth && !hlock_class(hlock - 1)->key); |
5133 | WARN_ON_ONCE(!hlock_class(hlock)->key); |
5134 | } |
5135 | |
5136 | if (!validate_chain(curr, hlock, chain_head, chain_key)) |
5137 | return 0; |
5138 | |
5139 | /* For lock_sync(), we are done here since no actual critical section */ |
5140 | if (hlock->sync) |
5141 | return 1; |
5142 | |
5143 | curr->curr_chain_key = chain_key; |
5144 | curr->lockdep_depth++; |
5145 | check_chain_key(curr); |
5146 | #ifdef CONFIG_DEBUG_LOCKDEP |
5147 | if (unlikely(!debug_locks)) |
5148 | return 0; |
5149 | #endif |
5150 | if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) { |
5151 | debug_locks_off(); |
5152 | print_lockdep_off(bug_msg: "BUG: MAX_LOCK_DEPTH too low!" ); |
5153 | printk(KERN_DEBUG "depth: %i max: %lu!\n" , |
5154 | curr->lockdep_depth, MAX_LOCK_DEPTH); |
5155 | |
5156 | lockdep_print_held_locks(current); |
5157 | debug_show_all_locks(); |
5158 | dump_stack(); |
5159 | |
5160 | return 0; |
5161 | } |
5162 | |
5163 | if (unlikely(curr->lockdep_depth > max_lockdep_depth)) |
5164 | max_lockdep_depth = curr->lockdep_depth; |
5165 | |
5166 | return 1; |
5167 | } |
5168 | |
5169 | static void print_unlock_imbalance_bug(struct task_struct *curr, |
5170 | struct lockdep_map *lock, |
5171 | unsigned long ip) |
5172 | { |
5173 | if (!debug_locks_off()) |
5174 | return; |
5175 | if (debug_locks_silent) |
5176 | return; |
5177 | |
5178 | pr_warn("\n" ); |
5179 | pr_warn("=====================================\n" ); |
5180 | pr_warn("WARNING: bad unlock balance detected!\n" ); |
5181 | print_kernel_ident(); |
5182 | pr_warn("-------------------------------------\n" ); |
5183 | pr_warn("%s/%d is trying to release lock (" , |
5184 | curr->comm, task_pid_nr(curr)); |
5185 | print_lockdep_cache(lock); |
5186 | pr_cont(") at:\n" ); |
5187 | print_ip_sym(KERN_WARNING, ip); |
5188 | pr_warn("but there are no more locks to release!\n" ); |
5189 | pr_warn("\nother info that might help us debug this:\n" ); |
5190 | lockdep_print_held_locks(p: curr); |
5191 | |
5192 | pr_warn("\nstack backtrace:\n" ); |
5193 | dump_stack(); |
5194 | } |
5195 | |
5196 | static noinstr int match_held_lock(const struct held_lock *hlock, |
5197 | const struct lockdep_map *lock) |
5198 | { |
5199 | if (hlock->instance == lock) |
5200 | return 1; |
5201 | |
5202 | if (hlock->references) { |
5203 | const struct lock_class *class = lock->class_cache[0]; |
5204 | |
5205 | if (!class) |
5206 | class = look_up_lock_class(lock, subclass: 0); |
5207 | |
5208 | /* |
5209 | * If look_up_lock_class() failed to find a class, we're trying |
5210 | * to test if we hold a lock that has never yet been acquired. |
5211 | * Clearly if the lock hasn't been acquired _ever_, we're not |
5212 | * holding it either, so report failure. |
5213 | */ |
5214 | if (!class) |
5215 | return 0; |
5216 | |
5217 | /* |
5218 | * References, but not a lock we're actually ref-counting? |
5219 | * State got messed up, follow the sites that change ->references |
5220 | * and try to make sense of it. |
5221 | */ |
5222 | if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock)) |
5223 | return 0; |
5224 | |
5225 | if (hlock->class_idx == class - lock_classes) |
5226 | return 1; |
5227 | } |
5228 | |
5229 | return 0; |
5230 | } |
5231 | |
5232 | /* @depth must not be zero */ |
5233 | static struct held_lock *find_held_lock(struct task_struct *curr, |
5234 | struct lockdep_map *lock, |
5235 | unsigned int depth, int *idx) |
5236 | { |
5237 | struct held_lock *ret, *hlock, *prev_hlock; |
5238 | int i; |
5239 | |
5240 | i = depth - 1; |
5241 | hlock = curr->held_locks + i; |
5242 | ret = hlock; |
5243 | if (match_held_lock(hlock, lock)) |
5244 | goto out; |
5245 | |
5246 | ret = NULL; |
5247 | for (i--, prev_hlock = hlock--; |
5248 | i >= 0; |
5249 | i--, prev_hlock = hlock--) { |
5250 | /* |
5251 | * We must not cross into another context: |
5252 | */ |
5253 | if (prev_hlock->irq_context != hlock->irq_context) { |
5254 | ret = NULL; |
5255 | break; |
5256 | } |
5257 | if (match_held_lock(hlock, lock)) { |
5258 | ret = hlock; |
5259 | break; |
5260 | } |
5261 | } |
5262 | |
5263 | out: |
5264 | *idx = i; |
5265 | return ret; |
5266 | } |
5267 | |
5268 | static int reacquire_held_locks(struct task_struct *curr, unsigned int depth, |
5269 | int idx, unsigned int *merged) |
5270 | { |
5271 | struct held_lock *hlock; |
5272 | int first_idx = idx; |
5273 | |
5274 | if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) |
5275 | return 0; |
5276 | |
5277 | for (hlock = curr->held_locks + idx; idx < depth; idx++, hlock++) { |
5278 | switch (__lock_acquire(lock: hlock->instance, |
5279 | subclass: hlock_class(hlock)->subclass, |
5280 | trylock: hlock->trylock, |
5281 | read: hlock->read, check: hlock->check, |
5282 | hardirqs_off: hlock->hardirqs_off, |
5283 | nest_lock: hlock->nest_lock, ip: hlock->acquire_ip, |
5284 | references: hlock->references, pin_count: hlock->pin_count, sync: 0)) { |
5285 | case 0: |
5286 | return 1; |
5287 | case 1: |
5288 | break; |
5289 | case 2: |
5290 | *merged += (idx == first_idx); |
5291 | break; |
5292 | default: |
5293 | WARN_ON(1); |
5294 | return 0; |
5295 | } |
5296 | } |
5297 | return 0; |
5298 | } |
5299 | |
5300 | static int |
5301 | __lock_set_class(struct lockdep_map *lock, const char *name, |
5302 | struct lock_class_key *key, unsigned int subclass, |
5303 | unsigned long ip) |
5304 | { |
5305 | struct task_struct *curr = current; |
5306 | unsigned int depth, merged = 0; |
5307 | struct held_lock *hlock; |
5308 | struct lock_class *class; |
5309 | int i; |
5310 | |
5311 | if (unlikely(!debug_locks)) |
5312 | return 0; |
5313 | |
5314 | depth = curr->lockdep_depth; |
5315 | /* |
5316 | * This function is about (re)setting the class of a held lock, |
5317 | * yet we're not actually holding any locks. Naughty user! |
5318 | */ |
5319 | if (DEBUG_LOCKS_WARN_ON(!depth)) |
5320 | return 0; |
5321 | |
5322 | hlock = find_held_lock(curr, lock, depth, idx: &i); |
5323 | if (!hlock) { |
5324 | print_unlock_imbalance_bug(curr, lock, ip); |
5325 | return 0; |
5326 | } |
5327 | |
5328 | lockdep_init_map_type(lock, name, key, 0, |
5329 | lock->wait_type_inner, |
5330 | lock->wait_type_outer, |
5331 | lock->lock_type); |
5332 | class = register_lock_class(lock, subclass, force: 0); |
5333 | hlock->class_idx = class - lock_classes; |
5334 | |
5335 | curr->lockdep_depth = i; |
5336 | curr->curr_chain_key = hlock->prev_chain_key; |
5337 | |
5338 | if (reacquire_held_locks(curr, depth, idx: i, merged: &merged)) |
5339 | return 0; |
5340 | |
5341 | /* |
5342 | * I took it apart and put it back together again, except now I have |
5343 | * these 'spare' parts.. where shall I put them. |
5344 | */ |
5345 | if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - merged)) |
5346 | return 0; |
5347 | return 1; |
5348 | } |
5349 | |
5350 | static int __lock_downgrade(struct lockdep_map *lock, unsigned long ip) |
5351 | { |
5352 | struct task_struct *curr = current; |
5353 | unsigned int depth, merged = 0; |
5354 | struct held_lock *hlock; |
5355 | int i; |
5356 | |
5357 | if (unlikely(!debug_locks)) |
5358 | return 0; |
5359 | |
5360 | depth = curr->lockdep_depth; |
5361 | /* |
5362 | * This function is about (re)setting the class of a held lock, |
5363 | * yet we're not actually holding any locks. Naughty user! |
5364 | */ |
5365 | if (DEBUG_LOCKS_WARN_ON(!depth)) |
5366 | return 0; |
5367 | |
5368 | hlock = find_held_lock(curr, lock, depth, idx: &i); |
5369 | if (!hlock) { |
5370 | print_unlock_imbalance_bug(curr, lock, ip); |
5371 | return 0; |
5372 | } |
5373 | |
5374 | curr->lockdep_depth = i; |
5375 | curr->curr_chain_key = hlock->prev_chain_key; |
5376 | |
5377 | WARN(hlock->read, "downgrading a read lock" ); |
5378 | hlock->read = 1; |
5379 | hlock->acquire_ip = ip; |
5380 | |
5381 | if (reacquire_held_locks(curr, depth, idx: i, merged: &merged)) |
5382 | return 0; |
5383 | |
5384 | /* Merging can't happen with unchanged classes.. */ |
5385 | if (DEBUG_LOCKS_WARN_ON(merged)) |
5386 | return 0; |
5387 | |
5388 | /* |
5389 | * I took it apart and put it back together again, except now I have |
5390 | * these 'spare' parts.. where shall I put them. |
5391 | */ |
5392 | if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth)) |
5393 | return 0; |
5394 | |
5395 | return 1; |
5396 | } |
5397 | |
5398 | /* |
5399 | * Remove the lock from the list of currently held locks - this gets |
5400 | * called on mutex_unlock()/spin_unlock*() (or on a failed |
5401 | * mutex_lock_interruptible()). |
5402 | */ |
5403 | static int |
5404 | __lock_release(struct lockdep_map *lock, unsigned long ip) |
5405 | { |
5406 | struct task_struct *curr = current; |
5407 | unsigned int depth, merged = 1; |
5408 | struct held_lock *hlock; |
5409 | int i; |
5410 | |
5411 | if (unlikely(!debug_locks)) |
5412 | return 0; |
5413 | |
5414 | depth = curr->lockdep_depth; |
5415 | /* |
5416 | * So we're all set to release this lock.. wait what lock? We don't |
5417 | * own any locks, you've been drinking again? |
5418 | */ |
5419 | if (depth <= 0) { |
5420 | print_unlock_imbalance_bug(curr, lock, ip); |
5421 | return 0; |
5422 | } |
5423 | |
5424 | /* |
5425 | * Check whether the lock exists in the current stack |
5426 | * of held locks: |
5427 | */ |
5428 | hlock = find_held_lock(curr, lock, depth, idx: &i); |
5429 | if (!hlock) { |
5430 | print_unlock_imbalance_bug(curr, lock, ip); |
5431 | return 0; |
5432 | } |
5433 | |
5434 | if (hlock->instance == lock) |
5435 | lock_release_holdtime(hlock); |
5436 | |
5437 | WARN(hlock->pin_count, "releasing a pinned lock\n" ); |
5438 | |
5439 | if (hlock->references) { |
5440 | hlock->references--; |
5441 | if (hlock->references) { |
5442 | /* |
5443 | * We had, and after removing one, still have |
5444 | * references, the current lock stack is still |
5445 | * valid. We're done! |
5446 | */ |
5447 | return 1; |
5448 | } |
5449 | } |
5450 | |
5451 | /* |
5452 | * We have the right lock to unlock, 'hlock' points to it. |
5453 | * Now we remove it from the stack, and add back the other |
5454 | * entries (if any), recalculating the hash along the way: |
5455 | */ |
5456 | |
5457 | curr->lockdep_depth = i; |
5458 | curr->curr_chain_key = hlock->prev_chain_key; |
5459 | |
5460 | /* |
5461 | * The most likely case is when the unlock is on the innermost |
5462 | * lock. In this case, we are done! |
5463 | */ |
5464 | if (i == depth-1) |
5465 | return 1; |
5466 | |
5467 | if (reacquire_held_locks(curr, depth, idx: i + 1, merged: &merged)) |
5468 | return 0; |
5469 | |
5470 | /* |
5471 | * We had N bottles of beer on the wall, we drank one, but now |
5472 | * there's not N-1 bottles of beer left on the wall... |
5473 | * Pouring two of the bottles together is acceptable. |
5474 | */ |
5475 | DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - merged); |
5476 | |
5477 | /* |
5478 | * Since reacquire_held_locks() would have called check_chain_key() |
5479 | * indirectly via __lock_acquire(), we don't need to do it again |
5480 | * on return. |
5481 | */ |
5482 | return 0; |
5483 | } |
5484 | |
5485 | static __always_inline |
5486 | int __lock_is_held(const struct lockdep_map *lock, int read) |
5487 | { |
5488 | struct task_struct *curr = current; |
5489 | int i; |
5490 | |
5491 | for (i = 0; i < curr->lockdep_depth; i++) { |
5492 | struct held_lock *hlock = curr->held_locks + i; |
5493 | |
5494 | if (match_held_lock(hlock, lock)) { |
5495 | if (read == -1 || !!hlock->read == read) |
5496 | return LOCK_STATE_HELD; |
5497 | |
5498 | return LOCK_STATE_NOT_HELD; |
5499 | } |
5500 | } |
5501 | |
5502 | return LOCK_STATE_NOT_HELD; |
5503 | } |
5504 | |
5505 | static struct pin_cookie __lock_pin_lock(struct lockdep_map *lock) |
5506 | { |
5507 | struct pin_cookie cookie = NIL_COOKIE; |
5508 | struct task_struct *curr = current; |
5509 | int i; |
5510 | |
5511 | if (unlikely(!debug_locks)) |
5512 | return cookie; |
5513 | |
5514 | for (i = 0; i < curr->lockdep_depth; i++) { |
5515 | struct held_lock *hlock = curr->held_locks + i; |
5516 | |
5517 | if (match_held_lock(hlock, lock)) { |
5518 | /* |
5519 | * Grab 16bits of randomness; this is sufficient to not |
5520 | * be guessable and still allows some pin nesting in |
5521 | * our u32 pin_count. |
5522 | */ |
5523 | cookie.val = 1 + (sched_clock() & 0xffff); |
5524 | hlock->pin_count += cookie.val; |
5525 | return cookie; |
5526 | } |
5527 | } |
5528 | |
5529 | WARN(1, "pinning an unheld lock\n" ); |
5530 | return cookie; |
5531 | } |
5532 | |
5533 | static void __lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie) |
5534 | { |
5535 | struct task_struct *curr = current; |
5536 | int i; |
5537 | |
5538 | if (unlikely(!debug_locks)) |
5539 | return; |
5540 | |
5541 | for (i = 0; i < curr->lockdep_depth; i++) { |
5542 | struct held_lock *hlock = curr->held_locks + i; |
5543 | |
5544 | if (match_held_lock(hlock, lock)) { |
5545 | hlock->pin_count += cookie.val; |
5546 | return; |
5547 | } |
5548 | } |
5549 | |
5550 | WARN(1, "pinning an unheld lock\n" ); |
5551 | } |
5552 | |
5553 | static void __lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie) |
5554 | { |
5555 | struct task_struct *curr = current; |
5556 | int i; |
5557 | |
5558 | if (unlikely(!debug_locks)) |
5559 | return; |
5560 | |
5561 | for (i = 0; i < curr->lockdep_depth; i++) { |
5562 | struct held_lock *hlock = curr->held_locks + i; |
5563 | |
5564 | if (match_held_lock(hlock, lock)) { |
5565 | if (WARN(!hlock->pin_count, "unpinning an unpinned lock\n" )) |
5566 | return; |
5567 | |
5568 | hlock->pin_count -= cookie.val; |
5569 | |
5570 | if (WARN((int)hlock->pin_count < 0, "pin count corrupted\n" )) |
5571 | hlock->pin_count = 0; |
5572 | |
5573 | return; |
5574 | } |
5575 | } |
5576 | |
5577 | WARN(1, "unpinning an unheld lock\n" ); |
5578 | } |
5579 | |
5580 | /* |
5581 | * Check whether we follow the irq-flags state precisely: |
5582 | */ |
5583 | static noinstr void check_flags(unsigned long flags) |
5584 | { |
5585 | #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) |
5586 | if (!debug_locks) |
5587 | return; |
5588 | |
5589 | /* Get the warning out.. */ |
5590 | instrumentation_begin(); |
5591 | |
5592 | if (irqs_disabled_flags(flags)) { |
5593 | if (DEBUG_LOCKS_WARN_ON(lockdep_hardirqs_enabled())) { |
5594 | printk("possible reason: unannotated irqs-off.\n" ); |
5595 | } |
5596 | } else { |
5597 | if (DEBUG_LOCKS_WARN_ON(!lockdep_hardirqs_enabled())) { |
5598 | printk("possible reason: unannotated irqs-on.\n" ); |
5599 | } |
5600 | } |
5601 | |
5602 | #ifndef CONFIG_PREEMPT_RT |
5603 | /* |
5604 | * We dont accurately track softirq state in e.g. |
5605 | * hardirq contexts (such as on 4KSTACKS), so only |
5606 | * check if not in hardirq contexts: |
5607 | */ |
5608 | if (!hardirq_count()) { |
5609 | if (softirq_count()) { |
5610 | /* like the above, but with softirqs */ |
5611 | DEBUG_LOCKS_WARN_ON(current->softirqs_enabled); |
5612 | } else { |
5613 | /* lick the above, does it taste good? */ |
5614 | DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled); |
5615 | } |
5616 | } |
5617 | #endif |
5618 | |
5619 | if (!debug_locks) |
5620 | print_irqtrace_events(current); |
5621 | |
5622 | instrumentation_end(); |
5623 | #endif |
5624 | } |
5625 | |
5626 | void lock_set_class(struct lockdep_map *lock, const char *name, |
5627 | struct lock_class_key *key, unsigned int subclass, |
5628 | unsigned long ip) |
5629 | { |
5630 | unsigned long flags; |
5631 | |
5632 | if (unlikely(!lockdep_enabled())) |
5633 | return; |
5634 | |
5635 | raw_local_irq_save(flags); |
5636 | lockdep_recursion_inc(); |
5637 | check_flags(flags); |
5638 | if (__lock_set_class(lock, name, key, subclass, ip)) |
5639 | check_chain_key(current); |
5640 | lockdep_recursion_finish(); |
5641 | raw_local_irq_restore(flags); |
5642 | } |
5643 | EXPORT_SYMBOL_GPL(lock_set_class); |
5644 | |
5645 | void lock_downgrade(struct lockdep_map *lock, unsigned long ip) |
5646 | { |
5647 | unsigned long flags; |
5648 | |
5649 | if (unlikely(!lockdep_enabled())) |
5650 | return; |
5651 | |
5652 | raw_local_irq_save(flags); |
5653 | lockdep_recursion_inc(); |
5654 | check_flags(flags); |
5655 | if (__lock_downgrade(lock, ip)) |
5656 | check_chain_key(current); |
5657 | lockdep_recursion_finish(); |
5658 | raw_local_irq_restore(flags); |
5659 | } |
5660 | EXPORT_SYMBOL_GPL(lock_downgrade); |
5661 | |
5662 | /* NMI context !!! */ |
5663 | static void verify_lock_unused(struct lockdep_map *lock, struct held_lock *hlock, int subclass) |
5664 | { |
5665 | #ifdef CONFIG_PROVE_LOCKING |
5666 | struct lock_class *class = look_up_lock_class(lock, subclass); |
5667 | unsigned long mask = LOCKF_USED; |
5668 | |
5669 | /* if it doesn't have a class (yet), it certainly hasn't been used yet */ |
5670 | if (!class) |
5671 | return; |
5672 | |
5673 | /* |
5674 | * READ locks only conflict with USED, such that if we only ever use |
5675 | * READ locks, there is no deadlock possible -- RCU. |
5676 | */ |
5677 | if (!hlock->read) |
5678 | mask |= LOCKF_USED_READ; |
5679 | |
5680 | if (!(class->usage_mask & mask)) |
5681 | return; |
5682 | |
5683 | hlock->class_idx = class - lock_classes; |
5684 | |
5685 | print_usage_bug(current, this: hlock, prev_bit: LOCK_USED, new_bit: LOCK_USAGE_STATES); |
5686 | #endif |
5687 | } |
5688 | |
5689 | static bool lockdep_nmi(void) |
5690 | { |
5691 | if (raw_cpu_read(lockdep_recursion)) |
5692 | return false; |
5693 | |
5694 | if (!in_nmi()) |
5695 | return false; |
5696 | |
5697 | return true; |
5698 | } |
5699 | |
5700 | /* |
5701 | * read_lock() is recursive if: |
5702 | * 1. We force lockdep think this way in selftests or |
5703 | * 2. The implementation is not queued read/write lock or |
5704 | * 3. The locker is at an in_interrupt() context. |
5705 | */ |
5706 | bool read_lock_is_recursive(void) |
5707 | { |
5708 | return force_read_lock_recursive || |
5709 | !IS_ENABLED(CONFIG_QUEUED_RWLOCKS) || |
5710 | in_interrupt(); |
5711 | } |
5712 | EXPORT_SYMBOL_GPL(read_lock_is_recursive); |
5713 | |
5714 | /* |
5715 | * We are not always called with irqs disabled - do that here, |
5716 | * and also avoid lockdep recursion: |
5717 | */ |
5718 | void lock_acquire(struct lockdep_map *lock, unsigned int subclass, |
5719 | int trylock, int read, int check, |
5720 | struct lockdep_map *nest_lock, unsigned long ip) |
5721 | { |
5722 | unsigned long flags; |
5723 | |
5724 | trace_lock_acquire(lock, subclass, trylock, read, check, next_lock: nest_lock, ip); |
5725 | |
5726 | if (!debug_locks) |
5727 | return; |
5728 | |
5729 | if (unlikely(!lockdep_enabled())) { |
5730 | /* XXX allow trylock from NMI ?!? */ |
5731 | if (lockdep_nmi() && !trylock) { |
5732 | struct held_lock hlock; |
5733 | |
5734 | hlock.acquire_ip = ip; |
5735 | hlock.instance = lock; |
5736 | hlock.nest_lock = nest_lock; |
5737 | hlock.irq_context = 2; // XXX |
5738 | hlock.trylock = trylock; |
5739 | hlock.read = read; |
5740 | hlock.check = check; |
5741 | hlock.hardirqs_off = true; |
5742 | hlock.references = 0; |
5743 | |
5744 | verify_lock_unused(lock, hlock: &hlock, subclass); |
5745 | } |
5746 | return; |
5747 | } |
5748 | |
5749 | raw_local_irq_save(flags); |
5750 | check_flags(flags); |
5751 | |
5752 | lockdep_recursion_inc(); |
5753 | __lock_acquire(lock, subclass, trylock, read, check, |
5754 | irqs_disabled_flags(flags), nest_lock, ip, references: 0, pin_count: 0, sync: 0); |
5755 | lockdep_recursion_finish(); |
5756 | raw_local_irq_restore(flags); |
5757 | } |
5758 | EXPORT_SYMBOL_GPL(lock_acquire); |
5759 | |
5760 | void lock_release(struct lockdep_map *lock, unsigned long ip) |
5761 | { |
5762 | unsigned long flags; |
5763 | |
5764 | trace_lock_release(lock, ip); |
5765 | |
5766 | if (unlikely(!lockdep_enabled())) |
5767 | return; |
5768 | |
5769 | raw_local_irq_save(flags); |
5770 | check_flags(flags); |
5771 | |
5772 | lockdep_recursion_inc(); |
5773 | if (__lock_release(lock, ip)) |
5774 | check_chain_key(current); |
5775 | lockdep_recursion_finish(); |
5776 | raw_local_irq_restore(flags); |
5777 | } |
5778 | EXPORT_SYMBOL_GPL(lock_release); |
5779 | |
5780 | /* |
5781 | * lock_sync() - A special annotation for synchronize_{s,}rcu()-like API. |
5782 | * |
5783 | * No actual critical section is created by the APIs annotated with this: these |
5784 | * APIs are used to wait for one or multiple critical sections (on other CPUs |
5785 | * or threads), and it means that calling these APIs inside these critical |
5786 | * sections is potential deadlock. |
5787 | */ |
5788 | void lock_sync(struct lockdep_map *lock, unsigned subclass, int read, |
5789 | int check, struct lockdep_map *nest_lock, unsigned long ip) |
5790 | { |
5791 | unsigned long flags; |
5792 | |
5793 | if (unlikely(!lockdep_enabled())) |
5794 | return; |
5795 | |
5796 | raw_local_irq_save(flags); |
5797 | check_flags(flags); |
5798 | |
5799 | lockdep_recursion_inc(); |
5800 | __lock_acquire(lock, subclass, trylock: 0, read, check, |
5801 | irqs_disabled_flags(flags), nest_lock, ip, references: 0, pin_count: 0, sync: 1); |
5802 | check_chain_key(current); |
5803 | lockdep_recursion_finish(); |
5804 | raw_local_irq_restore(flags); |
5805 | } |
5806 | EXPORT_SYMBOL_GPL(lock_sync); |
5807 | |
5808 | noinstr int lock_is_held_type(const struct lockdep_map *lock, int read) |
5809 | { |
5810 | unsigned long flags; |
5811 | int ret = LOCK_STATE_NOT_HELD; |
5812 | |
5813 | /* |
5814 | * Avoid false negative lockdep_assert_held() and |
5815 | * lockdep_assert_not_held(). |
5816 | */ |
5817 | if (unlikely(!lockdep_enabled())) |
5818 | return LOCK_STATE_UNKNOWN; |
5819 | |
5820 | raw_local_irq_save(flags); |
5821 | check_flags(flags); |
5822 | |
5823 | lockdep_recursion_inc(); |
5824 | ret = __lock_is_held(lock, read); |
5825 | lockdep_recursion_finish(); |
5826 | raw_local_irq_restore(flags); |
5827 | |
5828 | return ret; |
5829 | } |
5830 | EXPORT_SYMBOL_GPL(lock_is_held_type); |
5831 | NOKPROBE_SYMBOL(lock_is_held_type); |
5832 | |
5833 | struct pin_cookie lock_pin_lock(struct lockdep_map *lock) |
5834 | { |
5835 | struct pin_cookie cookie = NIL_COOKIE; |
5836 | unsigned long flags; |
5837 | |
5838 | if (unlikely(!lockdep_enabled())) |
5839 | return cookie; |
5840 | |
5841 | raw_local_irq_save(flags); |
5842 | check_flags(flags); |
5843 | |
5844 | lockdep_recursion_inc(); |
5845 | cookie = __lock_pin_lock(lock); |
5846 | lockdep_recursion_finish(); |
5847 | raw_local_irq_restore(flags); |
5848 | |
5849 | return cookie; |
5850 | } |
5851 | EXPORT_SYMBOL_GPL(lock_pin_lock); |
5852 | |
5853 | void lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie) |
5854 | { |
5855 | unsigned long flags; |
5856 | |
5857 | if (unlikely(!lockdep_enabled())) |
5858 | return; |
5859 | |
5860 | raw_local_irq_save(flags); |
5861 | check_flags(flags); |
5862 | |
5863 | lockdep_recursion_inc(); |
5864 | __lock_repin_lock(lock, cookie); |
5865 | lockdep_recursion_finish(); |
5866 | raw_local_irq_restore(flags); |
5867 | } |
5868 | EXPORT_SYMBOL_GPL(lock_repin_lock); |
5869 | |
5870 | void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie) |
5871 | { |
5872 | unsigned long flags; |
5873 | |
5874 | if (unlikely(!lockdep_enabled())) |
5875 | return; |
5876 | |
5877 | raw_local_irq_save(flags); |
5878 | check_flags(flags); |
5879 | |
5880 | lockdep_recursion_inc(); |
5881 | __lock_unpin_lock(lock, cookie); |
5882 | lockdep_recursion_finish(); |
5883 | raw_local_irq_restore(flags); |
5884 | } |
5885 | EXPORT_SYMBOL_GPL(lock_unpin_lock); |
5886 | |
5887 | #ifdef CONFIG_LOCK_STAT |
5888 | static void print_lock_contention_bug(struct task_struct *curr, |
5889 | struct lockdep_map *lock, |
5890 | unsigned long ip) |
5891 | { |
5892 | if (!debug_locks_off()) |
5893 | return; |
5894 | if (debug_locks_silent) |
5895 | return; |
5896 | |
5897 | pr_warn("\n" ); |
5898 | pr_warn("=================================\n" ); |
5899 | pr_warn("WARNING: bad contention detected!\n" ); |
5900 | print_kernel_ident(); |
5901 | pr_warn("---------------------------------\n" ); |
5902 | pr_warn("%s/%d is trying to contend lock (" , |
5903 | curr->comm, task_pid_nr(curr)); |
5904 | print_lockdep_cache(lock); |
5905 | pr_cont(") at:\n" ); |
5906 | print_ip_sym(KERN_WARNING, ip); |
5907 | pr_warn("but there are no locks held!\n" ); |
5908 | pr_warn("\nother info that might help us debug this:\n" ); |
5909 | lockdep_print_held_locks(p: curr); |
5910 | |
5911 | pr_warn("\nstack backtrace:\n" ); |
5912 | dump_stack(); |
5913 | } |
5914 | |
5915 | static void |
5916 | __lock_contended(struct lockdep_map *lock, unsigned long ip) |
5917 | { |
5918 | struct task_struct *curr = current; |
5919 | struct held_lock *hlock; |
5920 | struct lock_class_stats *stats; |
5921 | unsigned int depth; |
5922 | int i, contention_point, contending_point; |
5923 | |
5924 | depth = curr->lockdep_depth; |
5925 | /* |
5926 | * Whee, we contended on this lock, except it seems we're not |
5927 | * actually trying to acquire anything much at all.. |
5928 | */ |
5929 | if (DEBUG_LOCKS_WARN_ON(!depth)) |
5930 | return; |
5931 | |
5932 | hlock = find_held_lock(curr, lock, depth, idx: &i); |
5933 | if (!hlock) { |
5934 | print_lock_contention_bug(curr, lock, ip); |
5935 | return; |
5936 | } |
5937 | |
5938 | if (hlock->instance != lock) |
5939 | return; |
5940 | |
5941 | hlock->waittime_stamp = lockstat_clock(); |
5942 | |
5943 | contention_point = lock_point(points: hlock_class(hlock)->contention_point, ip); |
5944 | contending_point = lock_point(points: hlock_class(hlock)->contending_point, |
5945 | ip: lock->ip); |
5946 | |
5947 | stats = get_lock_stats(class: hlock_class(hlock)); |
5948 | if (contention_point < LOCKSTAT_POINTS) |
5949 | stats->contention_point[contention_point]++; |
5950 | if (contending_point < LOCKSTAT_POINTS) |
5951 | stats->contending_point[contending_point]++; |
5952 | if (lock->cpu != smp_processor_id()) |
5953 | stats->bounces[bounce_contended + !!hlock->read]++; |
5954 | } |
5955 | |
5956 | static void |
5957 | __lock_acquired(struct lockdep_map *lock, unsigned long ip) |
5958 | { |
5959 | struct task_struct *curr = current; |
5960 | struct held_lock *hlock; |
5961 | struct lock_class_stats *stats; |
5962 | unsigned int depth; |
5963 | u64 now, waittime = 0; |
5964 | int i, cpu; |
5965 | |
5966 | depth = curr->lockdep_depth; |
5967 | /* |
5968 | * Yay, we acquired ownership of this lock we didn't try to |
5969 | * acquire, how the heck did that happen? |
5970 | */ |
5971 | if (DEBUG_LOCKS_WARN_ON(!depth)) |
5972 | return; |
5973 | |
5974 | hlock = find_held_lock(curr, lock, depth, idx: &i); |
5975 | if (!hlock) { |
5976 | print_lock_contention_bug(curr, lock, _RET_IP_); |
5977 | return; |
5978 | } |
5979 | |
5980 | if (hlock->instance != lock) |
5981 | return; |
5982 | |
5983 | cpu = smp_processor_id(); |
5984 | if (hlock->waittime_stamp) { |
5985 | now = lockstat_clock(); |
5986 | waittime = now - hlock->waittime_stamp; |
5987 | hlock->holdtime_stamp = now; |
5988 | } |
5989 | |
5990 | stats = get_lock_stats(class: hlock_class(hlock)); |
5991 | if (waittime) { |
5992 | if (hlock->read) |
5993 | lock_time_inc(lt: &stats->read_waittime, time: waittime); |
5994 | else |
5995 | lock_time_inc(lt: &stats->write_waittime, time: waittime); |
5996 | } |
5997 | if (lock->cpu != cpu) |
5998 | stats->bounces[bounce_acquired + !!hlock->read]++; |
5999 | |
6000 | lock->cpu = cpu; |
6001 | lock->ip = ip; |
6002 | } |
6003 | |
6004 | void lock_contended(struct lockdep_map *lock, unsigned long ip) |
6005 | { |
6006 | unsigned long flags; |
6007 | |
6008 | trace_lock_contended(lock, ip); |
6009 | |
6010 | if (unlikely(!lock_stat || !lockdep_enabled())) |
6011 | return; |
6012 | |
6013 | raw_local_irq_save(flags); |
6014 | check_flags(flags); |
6015 | lockdep_recursion_inc(); |
6016 | __lock_contended(lock, ip); |
6017 | lockdep_recursion_finish(); |
6018 | raw_local_irq_restore(flags); |
6019 | } |
6020 | EXPORT_SYMBOL_GPL(lock_contended); |
6021 | |
6022 | void lock_acquired(struct lockdep_map *lock, unsigned long ip) |
6023 | { |
6024 | unsigned long flags; |
6025 | |
6026 | trace_lock_acquired(lock, ip); |
6027 | |
6028 | if (unlikely(!lock_stat || !lockdep_enabled())) |
6029 | return; |
6030 | |
6031 | raw_local_irq_save(flags); |
6032 | check_flags(flags); |
6033 | lockdep_recursion_inc(); |
6034 | __lock_acquired(lock, ip); |
6035 | lockdep_recursion_finish(); |
6036 | raw_local_irq_restore(flags); |
6037 | } |
6038 | EXPORT_SYMBOL_GPL(lock_acquired); |
6039 | #endif |
6040 | |
6041 | /* |
6042 | * Used by the testsuite, sanitize the validator state |
6043 | * after a simulated failure: |
6044 | */ |
6045 | |
6046 | void lockdep_reset(void) |
6047 | { |
6048 | unsigned long flags; |
6049 | int i; |
6050 | |
6051 | raw_local_irq_save(flags); |
6052 | lockdep_init_task(current); |
6053 | memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock)); |
6054 | nr_hardirq_chains = 0; |
6055 | nr_softirq_chains = 0; |
6056 | nr_process_chains = 0; |
6057 | debug_locks = 1; |
6058 | for (i = 0; i < CHAINHASH_SIZE; i++) |
6059 | INIT_HLIST_HEAD(chainhash_table + i); |
6060 | raw_local_irq_restore(flags); |
6061 | } |
6062 | |
6063 | /* Remove a class from a lock chain. Must be called with the graph lock held. */ |
6064 | static void remove_class_from_lock_chain(struct pending_free *pf, |
6065 | struct lock_chain *chain, |
6066 | struct lock_class *class) |
6067 | { |
6068 | #ifdef CONFIG_PROVE_LOCKING |
6069 | int i; |
6070 | |
6071 | for (i = chain->base; i < chain->base + chain->depth; i++) { |
6072 | if (chain_hlock_class_idx(hlock_id: chain_hlocks[i]) != class - lock_classes) |
6073 | continue; |
6074 | /* |
6075 | * Each lock class occurs at most once in a lock chain so once |
6076 | * we found a match we can break out of this loop. |
6077 | */ |
6078 | goto free_lock_chain; |
6079 | } |
6080 | /* Since the chain has not been modified, return. */ |
6081 | return; |
6082 | |
6083 | free_lock_chain: |
6084 | free_chain_hlocks(base: chain->base, size: chain->depth); |
6085 | /* Overwrite the chain key for concurrent RCU readers. */ |
6086 | WRITE_ONCE(chain->chain_key, INITIAL_CHAIN_KEY); |
6087 | dec_chains(irq_context: chain->irq_context); |
6088 | |
6089 | /* |
6090 | * Note: calling hlist_del_rcu() from inside a |
6091 | * hlist_for_each_entry_rcu() loop is safe. |
6092 | */ |
6093 | hlist_del_rcu(n: &chain->entry); |
6094 | __set_bit(chain - lock_chains, pf->lock_chains_being_freed); |
6095 | nr_zapped_lock_chains++; |
6096 | #endif |
6097 | } |
6098 | |
6099 | /* Must be called with the graph lock held. */ |
6100 | static void remove_class_from_lock_chains(struct pending_free *pf, |
6101 | struct lock_class *class) |
6102 | { |
6103 | struct lock_chain *chain; |
6104 | struct hlist_head *head; |
6105 | int i; |
6106 | |
6107 | for (i = 0; i < ARRAY_SIZE(chainhash_table); i++) { |
6108 | head = chainhash_table + i; |
6109 | hlist_for_each_entry_rcu(chain, head, entry) { |
6110 | remove_class_from_lock_chain(pf, chain, class); |
6111 | } |
6112 | } |
6113 | } |
6114 | |
6115 | /* |
6116 | * Remove all references to a lock class. The caller must hold the graph lock. |
6117 | */ |
6118 | static void zap_class(struct pending_free *pf, struct lock_class *class) |
6119 | { |
6120 | struct lock_list *entry; |
6121 | int i; |
6122 | |
6123 | WARN_ON_ONCE(!class->key); |
6124 | |
6125 | /* |
6126 | * Remove all dependencies this lock is |
6127 | * involved in: |
6128 | */ |
6129 | for_each_set_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) { |
6130 | entry = list_entries + i; |
6131 | if (entry->class != class && entry->links_to != class) |
6132 | continue; |
6133 | __clear_bit(i, list_entries_in_use); |
6134 | nr_list_entries--; |
6135 | list_del_rcu(entry: &entry->entry); |
6136 | } |
6137 | if (list_empty(head: &class->locks_after) && |
6138 | list_empty(head: &class->locks_before)) { |
6139 | list_move_tail(list: &class->lock_entry, head: &pf->zapped); |
6140 | hlist_del_rcu(n: &class->hash_entry); |
6141 | WRITE_ONCE(class->key, NULL); |
6142 | WRITE_ONCE(class->name, NULL); |
6143 | nr_lock_classes--; |
6144 | __clear_bit(class - lock_classes, lock_classes_in_use); |
6145 | if (class - lock_classes == max_lock_class_idx) |
6146 | max_lock_class_idx--; |
6147 | } else { |
6148 | WARN_ONCE(true, "%s() failed for class %s\n" , __func__, |
6149 | class->name); |
6150 | } |
6151 | |
6152 | remove_class_from_lock_chains(pf, class); |
6153 | nr_zapped_classes++; |
6154 | } |
6155 | |
6156 | static void reinit_class(struct lock_class *class) |
6157 | { |
6158 | WARN_ON_ONCE(!class->lock_entry.next); |
6159 | WARN_ON_ONCE(!list_empty(&class->locks_after)); |
6160 | WARN_ON_ONCE(!list_empty(&class->locks_before)); |
6161 | memset_startat(class, 0, key); |
6162 | WARN_ON_ONCE(!class->lock_entry.next); |
6163 | WARN_ON_ONCE(!list_empty(&class->locks_after)); |
6164 | WARN_ON_ONCE(!list_empty(&class->locks_before)); |
6165 | } |
6166 | |
6167 | static inline int within(const void *addr, void *start, unsigned long size) |
6168 | { |
6169 | return addr >= start && addr < start + size; |
6170 | } |
6171 | |
6172 | static bool inside_selftest(void) |
6173 | { |
6174 | return current == lockdep_selftest_task_struct; |
6175 | } |
6176 | |
6177 | /* The caller must hold the graph lock. */ |
6178 | static struct pending_free *get_pending_free(void) |
6179 | { |
6180 | return delayed_free.pf + delayed_free.index; |
6181 | } |
6182 | |
6183 | static void free_zapped_rcu(struct rcu_head *cb); |
6184 | |
6185 | /* |
6186 | * Schedule an RCU callback if no RCU callback is pending. Must be called with |
6187 | * the graph lock held. |
6188 | */ |
6189 | static void call_rcu_zapped(struct pending_free *pf) |
6190 | { |
6191 | WARN_ON_ONCE(inside_selftest()); |
6192 | |
6193 | if (list_empty(head: &pf->zapped)) |
6194 | return; |
6195 | |
6196 | if (delayed_free.scheduled) |
6197 | return; |
6198 | |
6199 | delayed_free.scheduled = true; |
6200 | |
6201 | WARN_ON_ONCE(delayed_free.pf + delayed_free.index != pf); |
6202 | delayed_free.index ^= 1; |
6203 | |
6204 | call_rcu(head: &delayed_free.rcu_head, func: free_zapped_rcu); |
6205 | } |
6206 | |
6207 | /* The caller must hold the graph lock. May be called from RCU context. */ |
6208 | static void __free_zapped_classes(struct pending_free *pf) |
6209 | { |
6210 | struct lock_class *class; |
6211 | |
6212 | check_data_structures(); |
6213 | |
6214 | list_for_each_entry(class, &pf->zapped, lock_entry) |
6215 | reinit_class(class); |
6216 | |
6217 | list_splice_init(list: &pf->zapped, head: &free_lock_classes); |
6218 | |
6219 | #ifdef CONFIG_PROVE_LOCKING |
6220 | bitmap_andnot(dst: lock_chains_in_use, src1: lock_chains_in_use, |
6221 | src2: pf->lock_chains_being_freed, ARRAY_SIZE(lock_chains)); |
6222 | bitmap_clear(map: pf->lock_chains_being_freed, start: 0, ARRAY_SIZE(lock_chains)); |
6223 | #endif |
6224 | } |
6225 | |
6226 | static void free_zapped_rcu(struct rcu_head *ch) |
6227 | { |
6228 | struct pending_free *pf; |
6229 | unsigned long flags; |
6230 | |
6231 | if (WARN_ON_ONCE(ch != &delayed_free.rcu_head)) |
6232 | return; |
6233 | |
6234 | raw_local_irq_save(flags); |
6235 | lockdep_lock(); |
6236 | |
6237 | /* closed head */ |
6238 | pf = delayed_free.pf + (delayed_free.index ^ 1); |
6239 | __free_zapped_classes(pf); |
6240 | delayed_free.scheduled = false; |
6241 | |
6242 | /* |
6243 | * If there's anything on the open list, close and start a new callback. |
6244 | */ |
6245 | call_rcu_zapped(pf: delayed_free.pf + delayed_free.index); |
6246 | |
6247 | lockdep_unlock(); |
6248 | raw_local_irq_restore(flags); |
6249 | } |
6250 | |
6251 | /* |
6252 | * Remove all lock classes from the class hash table and from the |
6253 | * all_lock_classes list whose key or name is in the address range [start, |
6254 | * start + size). Move these lock classes to the zapped_classes list. Must |
6255 | * be called with the graph lock held. |
6256 | */ |
6257 | static void __lockdep_free_key_range(struct pending_free *pf, void *start, |
6258 | unsigned long size) |
6259 | { |
6260 | struct lock_class *class; |
6261 | struct hlist_head *head; |
6262 | int i; |
6263 | |
6264 | /* Unhash all classes that were created by a module. */ |
6265 | for (i = 0; i < CLASSHASH_SIZE; i++) { |
6266 | head = classhash_table + i; |
6267 | hlist_for_each_entry_rcu(class, head, hash_entry) { |
6268 | if (!within(addr: class->key, start, size) && |
6269 | !within(addr: class->name, start, size)) |
6270 | continue; |
6271 | zap_class(pf, class); |
6272 | } |
6273 | } |
6274 | } |
6275 | |
6276 | /* |
6277 | * Used in module.c to remove lock classes from memory that is going to be |
6278 | * freed; and possibly re-used by other modules. |
6279 | * |
6280 | * We will have had one synchronize_rcu() before getting here, so we're |
6281 | * guaranteed nobody will look up these exact classes -- they're properly dead |
6282 | * but still allocated. |
6283 | */ |
6284 | static void lockdep_free_key_range_reg(void *start, unsigned long size) |
6285 | { |
6286 | struct pending_free *pf; |
6287 | unsigned long flags; |
6288 | |
6289 | init_data_structures_once(); |
6290 | |
6291 | raw_local_irq_save(flags); |
6292 | lockdep_lock(); |
6293 | pf = get_pending_free(); |
6294 | __lockdep_free_key_range(pf, start, size); |
6295 | call_rcu_zapped(pf); |
6296 | lockdep_unlock(); |
6297 | raw_local_irq_restore(flags); |
6298 | |
6299 | /* |
6300 | * Wait for any possible iterators from look_up_lock_class() to pass |
6301 | * before continuing to free the memory they refer to. |
6302 | */ |
6303 | synchronize_rcu(); |
6304 | } |
6305 | |
6306 | /* |
6307 | * Free all lockdep keys in the range [start, start+size). Does not sleep. |
6308 | * Ignores debug_locks. Must only be used by the lockdep selftests. |
6309 | */ |
6310 | static void lockdep_free_key_range_imm(void *start, unsigned long size) |
6311 | { |
6312 | struct pending_free *pf = delayed_free.pf; |
6313 | unsigned long flags; |
6314 | |
6315 | init_data_structures_once(); |
6316 | |
6317 | raw_local_irq_save(flags); |
6318 | lockdep_lock(); |
6319 | __lockdep_free_key_range(pf, start, size); |
6320 | __free_zapped_classes(pf); |
6321 | lockdep_unlock(); |
6322 | raw_local_irq_restore(flags); |
6323 | } |
6324 | |
6325 | void lockdep_free_key_range(void *start, unsigned long size) |
6326 | { |
6327 | init_data_structures_once(); |
6328 | |
6329 | if (inside_selftest()) |
6330 | lockdep_free_key_range_imm(start, size); |
6331 | else |
6332 | lockdep_free_key_range_reg(start, size); |
6333 | } |
6334 | |
6335 | /* |
6336 | * Check whether any element of the @lock->class_cache[] array refers to a |
6337 | * registered lock class. The caller must hold either the graph lock or the |
6338 | * RCU read lock. |
6339 | */ |
6340 | static bool lock_class_cache_is_registered(struct lockdep_map *lock) |
6341 | { |
6342 | struct lock_class *class; |
6343 | struct hlist_head *head; |
6344 | int i, j; |
6345 | |
6346 | for (i = 0; i < CLASSHASH_SIZE; i++) { |
6347 | head = classhash_table + i; |
6348 | hlist_for_each_entry_rcu(class, head, hash_entry) { |
6349 | for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++) |
6350 | if (lock->class_cache[j] == class) |
6351 | return true; |
6352 | } |
6353 | } |
6354 | return false; |
6355 | } |
6356 | |
6357 | /* The caller must hold the graph lock. Does not sleep. */ |
6358 | static void __lockdep_reset_lock(struct pending_free *pf, |
6359 | struct lockdep_map *lock) |
6360 | { |
6361 | struct lock_class *class; |
6362 | int j; |
6363 | |
6364 | /* |
6365 | * Remove all classes this lock might have: |
6366 | */ |
6367 | for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) { |
6368 | /* |
6369 | * If the class exists we look it up and zap it: |
6370 | */ |
6371 | class = look_up_lock_class(lock, subclass: j); |
6372 | if (class) |
6373 | zap_class(pf, class); |
6374 | } |
6375 | /* |
6376 | * Debug check: in the end all mapped classes should |
6377 | * be gone. |
6378 | */ |
6379 | if (WARN_ON_ONCE(lock_class_cache_is_registered(lock))) |
6380 | debug_locks_off(); |
6381 | } |
6382 | |
6383 | /* |
6384 | * Remove all information lockdep has about a lock if debug_locks == 1. Free |
6385 | * released data structures from RCU context. |
6386 | */ |
6387 | static void lockdep_reset_lock_reg(struct lockdep_map *lock) |
6388 | { |
6389 | struct pending_free *pf; |
6390 | unsigned long flags; |
6391 | int locked; |
6392 | |
6393 | raw_local_irq_save(flags); |
6394 | locked = graph_lock(); |
6395 | if (!locked) |
6396 | goto out_irq; |
6397 | |
6398 | pf = get_pending_free(); |
6399 | __lockdep_reset_lock(pf, lock); |
6400 | call_rcu_zapped(pf); |
6401 | |
6402 | graph_unlock(); |
6403 | out_irq: |
6404 | raw_local_irq_restore(flags); |
6405 | } |
6406 | |
6407 | /* |
6408 | * Reset a lock. Does not sleep. Ignores debug_locks. Must only be used by the |
6409 | * lockdep selftests. |
6410 | */ |
6411 | static void lockdep_reset_lock_imm(struct lockdep_map *lock) |
6412 | { |
6413 | struct pending_free *pf = delayed_free.pf; |
6414 | unsigned long flags; |
6415 | |
6416 | raw_local_irq_save(flags); |
6417 | lockdep_lock(); |
6418 | __lockdep_reset_lock(pf, lock); |
6419 | __free_zapped_classes(pf); |
6420 | lockdep_unlock(); |
6421 | raw_local_irq_restore(flags); |
6422 | } |
6423 | |
6424 | void lockdep_reset_lock(struct lockdep_map *lock) |
6425 | { |
6426 | init_data_structures_once(); |
6427 | |
6428 | if (inside_selftest()) |
6429 | lockdep_reset_lock_imm(lock); |
6430 | else |
6431 | lockdep_reset_lock_reg(lock); |
6432 | } |
6433 | |
6434 | /* |
6435 | * Unregister a dynamically allocated key. |
6436 | * |
6437 | * Unlike lockdep_register_key(), a search is always done to find a matching |
6438 | * key irrespective of debug_locks to avoid potential invalid access to freed |
6439 | * memory in lock_class entry. |
6440 | */ |
6441 | void lockdep_unregister_key(struct lock_class_key *key) |
6442 | { |
6443 | struct hlist_head *hash_head = keyhashentry(key); |
6444 | struct lock_class_key *k; |
6445 | struct pending_free *pf; |
6446 | unsigned long flags; |
6447 | bool found = false; |
6448 | |
6449 | might_sleep(); |
6450 | |
6451 | if (WARN_ON_ONCE(static_obj(key))) |
6452 | return; |
6453 | |
6454 | raw_local_irq_save(flags); |
6455 | lockdep_lock(); |
6456 | |
6457 | hlist_for_each_entry_rcu(k, hash_head, hash_entry) { |
6458 | if (k == key) { |
6459 | hlist_del_rcu(n: &k->hash_entry); |
6460 | found = true; |
6461 | break; |
6462 | } |
6463 | } |
6464 | WARN_ON_ONCE(!found && debug_locks); |
6465 | if (found) { |
6466 | pf = get_pending_free(); |
6467 | __lockdep_free_key_range(pf, start: key, size: 1); |
6468 | call_rcu_zapped(pf); |
6469 | } |
6470 | lockdep_unlock(); |
6471 | raw_local_irq_restore(flags); |
6472 | |
6473 | /* Wait until is_dynamic_key() has finished accessing k->hash_entry. */ |
6474 | synchronize_rcu(); |
6475 | } |
6476 | EXPORT_SYMBOL_GPL(lockdep_unregister_key); |
6477 | |
6478 | void __init lockdep_init(void) |
6479 | { |
6480 | printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n" ); |
6481 | |
6482 | printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n" , MAX_LOCKDEP_SUBCLASSES); |
6483 | printk("... MAX_LOCK_DEPTH: %lu\n" , MAX_LOCK_DEPTH); |
6484 | printk("... MAX_LOCKDEP_KEYS: %lu\n" , MAX_LOCKDEP_KEYS); |
6485 | printk("... CLASSHASH_SIZE: %lu\n" , CLASSHASH_SIZE); |
6486 | printk("... MAX_LOCKDEP_ENTRIES: %lu\n" , MAX_LOCKDEP_ENTRIES); |
6487 | printk("... MAX_LOCKDEP_CHAINS: %lu\n" , MAX_LOCKDEP_CHAINS); |
6488 | printk("... CHAINHASH_SIZE: %lu\n" , CHAINHASH_SIZE); |
6489 | |
6490 | printk(" memory used by lock dependency info: %zu kB\n" , |
6491 | (sizeof(lock_classes) + |
6492 | sizeof(lock_classes_in_use) + |
6493 | sizeof(classhash_table) + |
6494 | sizeof(list_entries) + |
6495 | sizeof(list_entries_in_use) + |
6496 | sizeof(chainhash_table) + |
6497 | sizeof(delayed_free) |
6498 | #ifdef CONFIG_PROVE_LOCKING |
6499 | + sizeof(lock_cq) |
6500 | + sizeof(lock_chains) |
6501 | + sizeof(lock_chains_in_use) |
6502 | + sizeof(chain_hlocks) |
6503 | #endif |
6504 | ) / 1024 |
6505 | ); |
6506 | |
6507 | #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) |
6508 | printk(" memory used for stack traces: %zu kB\n" , |
6509 | (sizeof(stack_trace) + sizeof(stack_trace_hash)) / 1024 |
6510 | ); |
6511 | #endif |
6512 | |
6513 | printk(" per task-struct memory footprint: %zu bytes\n" , |
6514 | sizeof(((struct task_struct *)NULL)->held_locks)); |
6515 | } |
6516 | |
6517 | static void |
6518 | print_freed_lock_bug(struct task_struct *curr, const void *mem_from, |
6519 | const void *mem_to, struct held_lock *hlock) |
6520 | { |
6521 | if (!debug_locks_off()) |
6522 | return; |
6523 | if (debug_locks_silent) |
6524 | return; |
6525 | |
6526 | pr_warn("\n" ); |
6527 | pr_warn("=========================\n" ); |
6528 | pr_warn("WARNING: held lock freed!\n" ); |
6529 | print_kernel_ident(); |
6530 | pr_warn("-------------------------\n" ); |
6531 | pr_warn("%s/%d is freeing memory %px-%px, with a lock still held there!\n" , |
6532 | curr->comm, task_pid_nr(curr), mem_from, mem_to-1); |
6533 | print_lock(hlock); |
6534 | lockdep_print_held_locks(p: curr); |
6535 | |
6536 | pr_warn("\nstack backtrace:\n" ); |
6537 | dump_stack(); |
6538 | } |
6539 | |
6540 | static inline int not_in_range(const void* mem_from, unsigned long mem_len, |
6541 | const void* lock_from, unsigned long lock_len) |
6542 | { |
6543 | return lock_from + lock_len <= mem_from || |
6544 | mem_from + mem_len <= lock_from; |
6545 | } |
6546 | |
6547 | /* |
6548 | * Called when kernel memory is freed (or unmapped), or if a lock |
6549 | * is destroyed or reinitialized - this code checks whether there is |
6550 | * any held lock in the memory range of <from> to <to>: |
6551 | */ |
6552 | void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len) |
6553 | { |
6554 | struct task_struct *curr = current; |
6555 | struct held_lock *hlock; |
6556 | unsigned long flags; |
6557 | int i; |
6558 | |
6559 | if (unlikely(!debug_locks)) |
6560 | return; |
6561 | |
6562 | raw_local_irq_save(flags); |
6563 | for (i = 0; i < curr->lockdep_depth; i++) { |
6564 | hlock = curr->held_locks + i; |
6565 | |
6566 | if (not_in_range(mem_from, mem_len, lock_from: hlock->instance, |
6567 | lock_len: sizeof(*hlock->instance))) |
6568 | continue; |
6569 | |
6570 | print_freed_lock_bug(curr, mem_from, mem_to: mem_from + mem_len, hlock); |
6571 | break; |
6572 | } |
6573 | raw_local_irq_restore(flags); |
6574 | } |
6575 | EXPORT_SYMBOL_GPL(debug_check_no_locks_freed); |
6576 | |
6577 | static void print_held_locks_bug(void) |
6578 | { |
6579 | if (!debug_locks_off()) |
6580 | return; |
6581 | if (debug_locks_silent) |
6582 | return; |
6583 | |
6584 | pr_warn("\n" ); |
6585 | pr_warn("====================================\n" ); |
6586 | pr_warn("WARNING: %s/%d still has locks held!\n" , |
6587 | current->comm, task_pid_nr(current)); |
6588 | print_kernel_ident(); |
6589 | pr_warn("------------------------------------\n" ); |
6590 | lockdep_print_held_locks(current); |
6591 | pr_warn("\nstack backtrace:\n" ); |
6592 | dump_stack(); |
6593 | } |
6594 | |
6595 | void debug_check_no_locks_held(void) |
6596 | { |
6597 | if (unlikely(current->lockdep_depth > 0)) |
6598 | print_held_locks_bug(); |
6599 | } |
6600 | EXPORT_SYMBOL_GPL(debug_check_no_locks_held); |
6601 | |
6602 | #ifdef __KERNEL__ |
6603 | void debug_show_all_locks(void) |
6604 | { |
6605 | struct task_struct *g, *p; |
6606 | |
6607 | if (unlikely(!debug_locks)) { |
6608 | pr_warn("INFO: lockdep is turned off.\n" ); |
6609 | return; |
6610 | } |
6611 | pr_warn("\nShowing all locks held in the system:\n" ); |
6612 | |
6613 | rcu_read_lock(); |
6614 | for_each_process_thread(g, p) { |
6615 | if (!p->lockdep_depth) |
6616 | continue; |
6617 | lockdep_print_held_locks(p); |
6618 | touch_nmi_watchdog(); |
6619 | touch_all_softlockup_watchdogs(); |
6620 | } |
6621 | rcu_read_unlock(); |
6622 | |
6623 | pr_warn("\n" ); |
6624 | pr_warn("=============================================\n\n" ); |
6625 | } |
6626 | EXPORT_SYMBOL_GPL(debug_show_all_locks); |
6627 | #endif |
6628 | |
6629 | /* |
6630 | * Careful: only use this function if you are sure that |
6631 | * the task cannot run in parallel! |
6632 | */ |
6633 | void debug_show_held_locks(struct task_struct *task) |
6634 | { |
6635 | if (unlikely(!debug_locks)) { |
6636 | printk("INFO: lockdep is turned off.\n" ); |
6637 | return; |
6638 | } |
6639 | lockdep_print_held_locks(p: task); |
6640 | } |
6641 | EXPORT_SYMBOL_GPL(debug_show_held_locks); |
6642 | |
6643 | asmlinkage __visible void lockdep_sys_exit(void) |
6644 | { |
6645 | struct task_struct *curr = current; |
6646 | |
6647 | if (unlikely(curr->lockdep_depth)) { |
6648 | if (!debug_locks_off()) |
6649 | return; |
6650 | pr_warn("\n" ); |
6651 | pr_warn("================================================\n" ); |
6652 | pr_warn("WARNING: lock held when returning to user space!\n" ); |
6653 | print_kernel_ident(); |
6654 | pr_warn("------------------------------------------------\n" ); |
6655 | pr_warn("%s/%d is leaving the kernel with locks still held!\n" , |
6656 | curr->comm, curr->pid); |
6657 | lockdep_print_held_locks(p: curr); |
6658 | } |
6659 | |
6660 | /* |
6661 | * The lock history for each syscall should be independent. So wipe the |
6662 | * slate clean on return to userspace. |
6663 | */ |
6664 | lockdep_invariant_state(force: false); |
6665 | } |
6666 | |
6667 | void lockdep_rcu_suspicious(const char *file, const int line, const char *s) |
6668 | { |
6669 | struct task_struct *curr = current; |
6670 | int dl = READ_ONCE(debug_locks); |
6671 | bool rcu = warn_rcu_enter(); |
6672 | |
6673 | /* Note: the following can be executed concurrently, so be careful. */ |
6674 | pr_warn("\n" ); |
6675 | pr_warn("=============================\n" ); |
6676 | pr_warn("WARNING: suspicious RCU usage\n" ); |
6677 | print_kernel_ident(); |
6678 | pr_warn("-----------------------------\n" ); |
6679 | pr_warn("%s:%d %s!\n" , file, line, s); |
6680 | pr_warn("\nother info that might help us debug this:\n\n" ); |
6681 | pr_warn("\n%srcu_scheduler_active = %d, debug_locks = %d\n%s" , |
6682 | !rcu_lockdep_current_cpu_online() |
6683 | ? "RCU used illegally from offline CPU!\n" |
6684 | : "" , |
6685 | rcu_scheduler_active, dl, |
6686 | dl ? "" : "Possible false positive due to lockdep disabling via debug_locks = 0\n" ); |
6687 | |
6688 | /* |
6689 | * If a CPU is in the RCU-free window in idle (ie: in the section |
6690 | * between ct_idle_enter() and ct_idle_exit(), then RCU |
6691 | * considers that CPU to be in an "extended quiescent state", |
6692 | * which means that RCU will be completely ignoring that CPU. |
6693 | * Therefore, rcu_read_lock() and friends have absolutely no |
6694 | * effect on a CPU running in that state. In other words, even if |
6695 | * such an RCU-idle CPU has called rcu_read_lock(), RCU might well |
6696 | * delete data structures out from under it. RCU really has no |
6697 | * choice here: we need to keep an RCU-free window in idle where |
6698 | * the CPU may possibly enter into low power mode. This way we can |
6699 | * notice an extended quiescent state to other CPUs that started a grace |
6700 | * period. Otherwise we would delay any grace period as long as we run |
6701 | * in the idle task. |
6702 | * |
6703 | * So complain bitterly if someone does call rcu_read_lock(), |
6704 | * rcu_read_lock_bh() and so on from extended quiescent states. |
6705 | */ |
6706 | if (!rcu_is_watching()) |
6707 | pr_warn("RCU used illegally from extended quiescent state!\n" ); |
6708 | |
6709 | lockdep_print_held_locks(p: curr); |
6710 | pr_warn("\nstack backtrace:\n" ); |
6711 | dump_stack(); |
6712 | warn_rcu_exit(rcu); |
6713 | } |
6714 | EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious); |
6715 | |