1// SPDX-License-Identifier: GPL-2.0
2/*
3 * trace task wakeup timings
4 *
5 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
6 * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
7 *
8 * Based on code from the latency_tracer, that is:
9 *
10 * Copyright (C) 2004-2006 Ingo Molnar
11 * Copyright (C) 2004 Nadia Yvette Chambers
12 */
13#include <linux/module.h>
14#include <linux/kallsyms.h>
15#include <linux/uaccess.h>
16#include <linux/ftrace.h>
17#include <linux/sched/rt.h>
18#include <linux/sched/deadline.h>
19#include <trace/events/sched.h>
20#include "trace.h"
21
22static struct trace_array *wakeup_trace;
23static int __read_mostly tracer_enabled;
24
25static struct task_struct *wakeup_task;
26static int wakeup_cpu;
27static int wakeup_current_cpu;
28static unsigned wakeup_prio = -1;
29static bool wakeup_rt;
30static bool wakeup_dl;
31static bool tracing_dl;
32
33static arch_spinlock_t wakeup_lock =
34 (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
35
36static void wakeup_reset(struct trace_array *tr);
37static void __wakeup_reset(struct trace_array *tr);
38static int start_func_tracer(struct trace_array *tr, int graph);
39static void stop_func_tracer(struct trace_array *tr, int graph);
40
41static int save_flags;
42
43#ifdef CONFIG_FUNCTION_GRAPH_TRACER
44# define is_graph(tr) ((tr)->trace_flags & TRACE_ITER_DISPLAY_GRAPH)
45#else
46# define is_graph(tr) false
47#endif
48
49#ifdef CONFIG_FUNCTION_TRACER
50
51static bool function_enabled;
52
53/*
54 * Prologue for the wakeup function tracers.
55 *
56 * Returns 1 if it is OK to continue, and preemption
57 * is disabled and data->disabled is incremented.
58 * 0 if the trace is to be ignored, and preemption
59 * is not disabled and data->disabled is
60 * kept the same.
61 *
62 * Note, this function is also used outside this ifdef but
63 * inside the #ifdef of the function graph tracer below.
64 * This is OK, since the function graph tracer is
65 * dependent on the function tracer.
66 */
67static int
68func_prolog_preempt_disable(struct trace_array *tr,
69 struct trace_array_cpu **data,
70 unsigned int *trace_ctx)
71{
72 long disabled;
73 int cpu;
74
75 if (likely(!wakeup_task))
76 return 0;
77
78 *trace_ctx = tracing_gen_ctx();
79 preempt_disable_notrace();
80
81 cpu = raw_smp_processor_id();
82 if (cpu != wakeup_current_cpu)
83 goto out_enable;
84
85 *data = per_cpu_ptr(tr->array_buffer.data, cpu);
86 disabled = atomic_inc_return(v: &(*data)->disabled);
87 if (unlikely(disabled != 1))
88 goto out;
89
90 return 1;
91
92out:
93 atomic_dec(v: &(*data)->disabled);
94
95out_enable:
96 preempt_enable_notrace();
97 return 0;
98}
99
100#ifdef CONFIG_FUNCTION_GRAPH_TRACER
101
102static int wakeup_display_graph(struct trace_array *tr, int set)
103{
104 if (!(is_graph(tr) ^ set))
105 return 0;
106
107 stop_func_tracer(tr, graph: !set);
108
109 wakeup_reset(tr: wakeup_trace);
110 tr->max_latency = 0;
111
112 return start_func_tracer(tr, graph: set);
113}
114
115static int wakeup_graph_entry(struct ftrace_graph_ent *trace)
116{
117 struct trace_array *tr = wakeup_trace;
118 struct trace_array_cpu *data;
119 unsigned int trace_ctx;
120 int ret = 0;
121
122 if (ftrace_graph_ignore_func(trace))
123 return 0;
124 /*
125 * Do not trace a function if it's filtered by set_graph_notrace.
126 * Make the index of ret stack negative to indicate that it should
127 * ignore further functions. But it needs its own ret stack entry
128 * to recover the original index in order to continue tracing after
129 * returning from the function.
130 */
131 if (ftrace_graph_notrace_addr(addr: trace->func))
132 return 1;
133
134 if (!func_prolog_preempt_disable(tr, data: &data, trace_ctx: &trace_ctx))
135 return 0;
136
137 ret = __trace_graph_entry(tr, trace, trace_ctx);
138 atomic_dec(v: &data->disabled);
139 preempt_enable_notrace();
140
141 return ret;
142}
143
144static void wakeup_graph_return(struct ftrace_graph_ret *trace)
145{
146 struct trace_array *tr = wakeup_trace;
147 struct trace_array_cpu *data;
148 unsigned int trace_ctx;
149
150 ftrace_graph_addr_finish(trace);
151
152 if (!func_prolog_preempt_disable(tr, data: &data, trace_ctx: &trace_ctx))
153 return;
154
155 __trace_graph_return(tr, trace, trace_ctx);
156 atomic_dec(v: &data->disabled);
157
158 preempt_enable_notrace();
159 return;
160}
161
162static struct fgraph_ops fgraph_wakeup_ops = {
163 .entryfunc = &wakeup_graph_entry,
164 .retfunc = &wakeup_graph_return,
165};
166
167static void wakeup_trace_open(struct trace_iterator *iter)
168{
169 if (is_graph(iter->tr))
170 graph_trace_open(iter);
171 else
172 iter->private = NULL;
173}
174
175static void wakeup_trace_close(struct trace_iterator *iter)
176{
177 if (iter->private)
178 graph_trace_close(iter);
179}
180
181#define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_PROC | \
182 TRACE_GRAPH_PRINT_CPU | \
183 TRACE_GRAPH_PRINT_REL_TIME | \
184 TRACE_GRAPH_PRINT_DURATION | \
185 TRACE_GRAPH_PRINT_OVERHEAD | \
186 TRACE_GRAPH_PRINT_IRQS)
187
188static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
189{
190 /*
191 * In graph mode call the graph tracer output function,
192 * otherwise go with the TRACE_FN event handler
193 */
194 if (is_graph(iter->tr))
195 return print_graph_function_flags(iter, GRAPH_TRACER_FLAGS);
196
197 return TRACE_TYPE_UNHANDLED;
198}
199
200static void wakeup_print_header(struct seq_file *s)
201{
202 if (is_graph(wakeup_trace))
203 print_graph_headers_flags(s, GRAPH_TRACER_FLAGS);
204 else
205 trace_default_header(m: s);
206}
207#endif /* else CONFIG_FUNCTION_GRAPH_TRACER */
208
209/*
210 * wakeup uses its own tracer function to keep the overhead down:
211 */
212static void
213wakeup_tracer_call(unsigned long ip, unsigned long parent_ip,
214 struct ftrace_ops *op, struct ftrace_regs *fregs)
215{
216 struct trace_array *tr = wakeup_trace;
217 struct trace_array_cpu *data;
218 unsigned long flags;
219 unsigned int trace_ctx;
220
221 if (!func_prolog_preempt_disable(tr, data: &data, trace_ctx: &trace_ctx))
222 return;
223
224 local_irq_save(flags);
225 trace_function(tr, ip, parent_ip, trace_ctx);
226 local_irq_restore(flags);
227
228 atomic_dec(v: &data->disabled);
229 preempt_enable_notrace();
230}
231
232static int register_wakeup_function(struct trace_array *tr, int graph, int set)
233{
234 int ret;
235
236 /* 'set' is set if TRACE_ITER_FUNCTION is about to be set */
237 if (function_enabled || (!set && !(tr->trace_flags & TRACE_ITER_FUNCTION)))
238 return 0;
239
240 if (graph)
241 ret = register_ftrace_graph(ops: &fgraph_wakeup_ops);
242 else
243 ret = register_ftrace_function(ops: tr->ops);
244
245 if (!ret)
246 function_enabled = true;
247
248 return ret;
249}
250
251static void unregister_wakeup_function(struct trace_array *tr, int graph)
252{
253 if (!function_enabled)
254 return;
255
256 if (graph)
257 unregister_ftrace_graph(ops: &fgraph_wakeup_ops);
258 else
259 unregister_ftrace_function(ops: tr->ops);
260
261 function_enabled = false;
262}
263
264static int wakeup_function_set(struct trace_array *tr, u32 mask, int set)
265{
266 if (!(mask & TRACE_ITER_FUNCTION))
267 return 0;
268
269 if (set)
270 register_wakeup_function(tr, is_graph(tr), set: 1);
271 else
272 unregister_wakeup_function(tr, is_graph(tr));
273 return 1;
274}
275#else /* CONFIG_FUNCTION_TRACER */
276static int register_wakeup_function(struct trace_array *tr, int graph, int set)
277{
278 return 0;
279}
280static void unregister_wakeup_function(struct trace_array *tr, int graph) { }
281static int wakeup_function_set(struct trace_array *tr, u32 mask, int set)
282{
283 return 0;
284}
285#endif /* else CONFIG_FUNCTION_TRACER */
286
287#ifndef CONFIG_FUNCTION_GRAPH_TRACER
288static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
289{
290 return TRACE_TYPE_UNHANDLED;
291}
292
293static void wakeup_trace_open(struct trace_iterator *iter) { }
294static void wakeup_trace_close(struct trace_iterator *iter) { }
295
296static void wakeup_print_header(struct seq_file *s)
297{
298 trace_default_header(s);
299}
300#endif /* !CONFIG_FUNCTION_GRAPH_TRACER */
301
302static void
303__trace_function(struct trace_array *tr,
304 unsigned long ip, unsigned long parent_ip,
305 unsigned int trace_ctx)
306{
307 if (is_graph(tr))
308 trace_graph_function(tr, ip, parent_ip, trace_ctx);
309 else
310 trace_function(tr, ip, parent_ip, trace_ctx);
311}
312
313static int wakeup_flag_changed(struct trace_array *tr, u32 mask, int set)
314{
315 struct tracer *tracer = tr->current_trace;
316
317 if (wakeup_function_set(tr, mask, set))
318 return 0;
319
320#ifdef CONFIG_FUNCTION_GRAPH_TRACER
321 if (mask & TRACE_ITER_DISPLAY_GRAPH)
322 return wakeup_display_graph(tr, set);
323#endif
324
325 return trace_keep_overwrite(tracer, mask, set);
326}
327
328static int start_func_tracer(struct trace_array *tr, int graph)
329{
330 int ret;
331
332 ret = register_wakeup_function(tr, graph, set: 0);
333
334 if (!ret && tracing_is_enabled())
335 tracer_enabled = 1;
336 else
337 tracer_enabled = 0;
338
339 return ret;
340}
341
342static void stop_func_tracer(struct trace_array *tr, int graph)
343{
344 tracer_enabled = 0;
345
346 unregister_wakeup_function(tr, graph);
347}
348
349/*
350 * Should this new latency be reported/recorded?
351 */
352static bool report_latency(struct trace_array *tr, u64 delta)
353{
354 if (tracing_thresh) {
355 if (delta < tracing_thresh)
356 return false;
357 } else {
358 if (delta <= tr->max_latency)
359 return false;
360 }
361 return true;
362}
363
364static void
365probe_wakeup_migrate_task(void *ignore, struct task_struct *task, int cpu)
366{
367 if (task != wakeup_task)
368 return;
369
370 wakeup_current_cpu = cpu;
371}
372
373static void
374tracing_sched_switch_trace(struct trace_array *tr,
375 struct task_struct *prev,
376 struct task_struct *next,
377 unsigned int trace_ctx)
378{
379 struct trace_event_call *call = &event_context_switch;
380 struct trace_buffer *buffer = tr->array_buffer.buffer;
381 struct ring_buffer_event *event;
382 struct ctx_switch_entry *entry;
383
384 event = trace_buffer_lock_reserve(buffer, type: TRACE_CTX,
385 len: sizeof(*entry), trace_ctx);
386 if (!event)
387 return;
388 entry = ring_buffer_event_data(event);
389 entry->prev_pid = prev->pid;
390 entry->prev_prio = prev->prio;
391 entry->prev_state = task_state_index(tsk: prev);
392 entry->next_pid = next->pid;
393 entry->next_prio = next->prio;
394 entry->next_state = task_state_index(tsk: next);
395 entry->next_cpu = task_cpu(p: next);
396
397 if (!call_filter_check_discard(call, rec: entry, buffer, event))
398 trace_buffer_unlock_commit(tr, buffer, event, trace_ctx);
399}
400
401static void
402tracing_sched_wakeup_trace(struct trace_array *tr,
403 struct task_struct *wakee,
404 struct task_struct *curr,
405 unsigned int trace_ctx)
406{
407 struct trace_event_call *call = &event_wakeup;
408 struct ring_buffer_event *event;
409 struct ctx_switch_entry *entry;
410 struct trace_buffer *buffer = tr->array_buffer.buffer;
411
412 event = trace_buffer_lock_reserve(buffer, type: TRACE_WAKE,
413 len: sizeof(*entry), trace_ctx);
414 if (!event)
415 return;
416 entry = ring_buffer_event_data(event);
417 entry->prev_pid = curr->pid;
418 entry->prev_prio = curr->prio;
419 entry->prev_state = task_state_index(tsk: curr);
420 entry->next_pid = wakee->pid;
421 entry->next_prio = wakee->prio;
422 entry->next_state = task_state_index(tsk: wakee);
423 entry->next_cpu = task_cpu(p: wakee);
424
425 if (!call_filter_check_discard(call, rec: entry, buffer, event))
426 trace_buffer_unlock_commit(tr, buffer, event, trace_ctx);
427}
428
429static void notrace
430probe_wakeup_sched_switch(void *ignore, bool preempt,
431 struct task_struct *prev, struct task_struct *next,
432 unsigned int prev_state)
433{
434 struct trace_array_cpu *data;
435 u64 T0, T1, delta;
436 unsigned long flags;
437 long disabled;
438 int cpu;
439 unsigned int trace_ctx;
440
441 tracing_record_cmdline(task: prev);
442
443 if (unlikely(!tracer_enabled))
444 return;
445
446 /*
447 * When we start a new trace, we set wakeup_task to NULL
448 * and then set tracer_enabled = 1. We want to make sure
449 * that another CPU does not see the tracer_enabled = 1
450 * and the wakeup_task with an older task, that might
451 * actually be the same as next.
452 */
453 smp_rmb();
454
455 if (next != wakeup_task)
456 return;
457
458 /* disable local data, not wakeup_cpu data */
459 cpu = raw_smp_processor_id();
460 disabled = atomic_inc_return(v: &per_cpu_ptr(wakeup_trace->array_buffer.data, cpu)->disabled);
461 if (likely(disabled != 1))
462 goto out;
463
464 local_irq_save(flags);
465 trace_ctx = tracing_gen_ctx_flags(irqflags: flags);
466
467 arch_spin_lock(&wakeup_lock);
468
469 /* We could race with grabbing wakeup_lock */
470 if (unlikely(!tracer_enabled || next != wakeup_task))
471 goto out_unlock;
472
473 /* The task we are waiting for is waking up */
474 data = per_cpu_ptr(wakeup_trace->array_buffer.data, wakeup_cpu);
475
476 __trace_function(tr: wakeup_trace, CALLER_ADDR0, CALLER_ADDR1, trace_ctx);
477 tracing_sched_switch_trace(tr: wakeup_trace, prev, next, trace_ctx);
478 __trace_stack(tr: wakeup_trace, trace_ctx, skip: 0);
479
480 T0 = data->preempt_timestamp;
481 T1 = ftrace_now(cpu);
482 delta = T1-T0;
483
484 if (!report_latency(tr: wakeup_trace, delta))
485 goto out_unlock;
486
487 if (likely(!is_tracing_stopped())) {
488 wakeup_trace->max_latency = delta;
489 update_max_tr(tr: wakeup_trace, tsk: wakeup_task, cpu: wakeup_cpu, NULL);
490 }
491
492out_unlock:
493 __wakeup_reset(tr: wakeup_trace);
494 arch_spin_unlock(&wakeup_lock);
495 local_irq_restore(flags);
496out:
497 atomic_dec(v: &per_cpu_ptr(wakeup_trace->array_buffer.data, cpu)->disabled);
498}
499
500static void __wakeup_reset(struct trace_array *tr)
501{
502 wakeup_cpu = -1;
503 wakeup_prio = -1;
504 tracing_dl = false;
505
506 if (wakeup_task)
507 put_task_struct(t: wakeup_task);
508
509 wakeup_task = NULL;
510}
511
512static void wakeup_reset(struct trace_array *tr)
513{
514 unsigned long flags;
515
516 tracing_reset_online_cpus(buf: &tr->array_buffer);
517
518 local_irq_save(flags);
519 arch_spin_lock(&wakeup_lock);
520 __wakeup_reset(tr);
521 arch_spin_unlock(&wakeup_lock);
522 local_irq_restore(flags);
523}
524
525static void
526probe_wakeup(void *ignore, struct task_struct *p)
527{
528 struct trace_array_cpu *data;
529 int cpu = smp_processor_id();
530 long disabled;
531 unsigned int trace_ctx;
532
533 if (likely(!tracer_enabled))
534 return;
535
536 tracing_record_cmdline(task: p);
537 tracing_record_cmdline(current);
538
539 /*
540 * Semantic is like this:
541 * - wakeup tracer handles all tasks in the system, independently
542 * from their scheduling class;
543 * - wakeup_rt tracer handles tasks belonging to sched_dl and
544 * sched_rt class;
545 * - wakeup_dl handles tasks belonging to sched_dl class only.
546 */
547 if (tracing_dl || (wakeup_dl && !dl_task(p)) ||
548 (wakeup_rt && !dl_task(p) && !rt_task(p)) ||
549 (!dl_task(p) && (p->prio >= wakeup_prio || p->prio >= current->prio)))
550 return;
551
552 disabled = atomic_inc_return(v: &per_cpu_ptr(wakeup_trace->array_buffer.data, cpu)->disabled);
553 if (unlikely(disabled != 1))
554 goto out;
555
556 trace_ctx = tracing_gen_ctx();
557
558 /* interrupts should be off from try_to_wake_up */
559 arch_spin_lock(&wakeup_lock);
560
561 /* check for races. */
562 if (!tracer_enabled || tracing_dl ||
563 (!dl_task(p) && p->prio >= wakeup_prio))
564 goto out_locked;
565
566 /* reset the trace */
567 __wakeup_reset(tr: wakeup_trace);
568
569 wakeup_cpu = task_cpu(p);
570 wakeup_current_cpu = wakeup_cpu;
571 wakeup_prio = p->prio;
572
573 /*
574 * Once you start tracing a -deadline task, don't bother tracing
575 * another task until the first one wakes up.
576 */
577 if (dl_task(p))
578 tracing_dl = true;
579 else
580 tracing_dl = false;
581
582 wakeup_task = get_task_struct(t: p);
583
584 data = per_cpu_ptr(wakeup_trace->array_buffer.data, wakeup_cpu);
585 data->preempt_timestamp = ftrace_now(cpu);
586 tracing_sched_wakeup_trace(tr: wakeup_trace, wakee: p, current, trace_ctx);
587 __trace_stack(tr: wakeup_trace, trace_ctx, skip: 0);
588
589 /*
590 * We must be careful in using CALLER_ADDR2. But since wake_up
591 * is not called by an assembly function (where as schedule is)
592 * it should be safe to use it here.
593 */
594 __trace_function(tr: wakeup_trace, CALLER_ADDR1, CALLER_ADDR2, trace_ctx);
595
596out_locked:
597 arch_spin_unlock(&wakeup_lock);
598out:
599 atomic_dec(v: &per_cpu_ptr(wakeup_trace->array_buffer.data, cpu)->disabled);
600}
601
602static void start_wakeup_tracer(struct trace_array *tr)
603{
604 int ret;
605
606 ret = register_trace_sched_wakeup(probe: probe_wakeup, NULL);
607 if (ret) {
608 pr_info("wakeup trace: Couldn't activate tracepoint"
609 " probe to kernel_sched_wakeup\n");
610 return;
611 }
612
613 ret = register_trace_sched_wakeup_new(probe: probe_wakeup, NULL);
614 if (ret) {
615 pr_info("wakeup trace: Couldn't activate tracepoint"
616 " probe to kernel_sched_wakeup_new\n");
617 goto fail_deprobe;
618 }
619
620 ret = register_trace_sched_switch(probe: probe_wakeup_sched_switch, NULL);
621 if (ret) {
622 pr_info("sched trace: Couldn't activate tracepoint"
623 " probe to kernel_sched_switch\n");
624 goto fail_deprobe_wake_new;
625 }
626
627 ret = register_trace_sched_migrate_task(probe: probe_wakeup_migrate_task, NULL);
628 if (ret) {
629 pr_info("wakeup trace: Couldn't activate tracepoint"
630 " probe to kernel_sched_migrate_task\n");
631 goto fail_deprobe_sched_switch;
632 }
633
634 wakeup_reset(tr);
635
636 /*
637 * Don't let the tracer_enabled = 1 show up before
638 * the wakeup_task is reset. This may be overkill since
639 * wakeup_reset does a spin_unlock after setting the
640 * wakeup_task to NULL, but I want to be safe.
641 * This is a slow path anyway.
642 */
643 smp_wmb();
644
645 if (start_func_tracer(tr, is_graph(tr)))
646 printk(KERN_ERR "failed to start wakeup tracer\n");
647
648 return;
649fail_deprobe_sched_switch:
650 unregister_trace_sched_switch(probe: probe_wakeup_sched_switch, NULL);
651fail_deprobe_wake_new:
652 unregister_trace_sched_wakeup_new(probe: probe_wakeup, NULL);
653fail_deprobe:
654 unregister_trace_sched_wakeup(probe: probe_wakeup, NULL);
655}
656
657static void stop_wakeup_tracer(struct trace_array *tr)
658{
659 tracer_enabled = 0;
660 stop_func_tracer(tr, is_graph(tr));
661 unregister_trace_sched_switch(probe: probe_wakeup_sched_switch, NULL);
662 unregister_trace_sched_wakeup_new(probe: probe_wakeup, NULL);
663 unregister_trace_sched_wakeup(probe: probe_wakeup, NULL);
664 unregister_trace_sched_migrate_task(probe: probe_wakeup_migrate_task, NULL);
665}
666
667static bool wakeup_busy;
668
669static int __wakeup_tracer_init(struct trace_array *tr)
670{
671 save_flags = tr->trace_flags;
672
673 /* non overwrite screws up the latency tracers */
674 set_tracer_flag(tr, mask: TRACE_ITER_OVERWRITE, enabled: 1);
675 set_tracer_flag(tr, mask: TRACE_ITER_LATENCY_FMT, enabled: 1);
676
677 tr->max_latency = 0;
678 wakeup_trace = tr;
679 ftrace_init_array_ops(tr, func: wakeup_tracer_call);
680 start_wakeup_tracer(tr);
681
682 wakeup_busy = true;
683 return 0;
684}
685
686static int wakeup_tracer_init(struct trace_array *tr)
687{
688 if (wakeup_busy)
689 return -EBUSY;
690
691 wakeup_dl = false;
692 wakeup_rt = false;
693 return __wakeup_tracer_init(tr);
694}
695
696static int wakeup_rt_tracer_init(struct trace_array *tr)
697{
698 if (wakeup_busy)
699 return -EBUSY;
700
701 wakeup_dl = false;
702 wakeup_rt = true;
703 return __wakeup_tracer_init(tr);
704}
705
706static int wakeup_dl_tracer_init(struct trace_array *tr)
707{
708 if (wakeup_busy)
709 return -EBUSY;
710
711 wakeup_dl = true;
712 wakeup_rt = false;
713 return __wakeup_tracer_init(tr);
714}
715
716static void wakeup_tracer_reset(struct trace_array *tr)
717{
718 int lat_flag = save_flags & TRACE_ITER_LATENCY_FMT;
719 int overwrite_flag = save_flags & TRACE_ITER_OVERWRITE;
720
721 stop_wakeup_tracer(tr);
722 /* make sure we put back any tasks we are tracing */
723 wakeup_reset(tr);
724
725 set_tracer_flag(tr, mask: TRACE_ITER_LATENCY_FMT, enabled: lat_flag);
726 set_tracer_flag(tr, mask: TRACE_ITER_OVERWRITE, enabled: overwrite_flag);
727 ftrace_reset_array_ops(tr);
728 wakeup_busy = false;
729}
730
731static void wakeup_tracer_start(struct trace_array *tr)
732{
733 wakeup_reset(tr);
734 tracer_enabled = 1;
735}
736
737static void wakeup_tracer_stop(struct trace_array *tr)
738{
739 tracer_enabled = 0;
740}
741
742static struct tracer wakeup_tracer __read_mostly =
743{
744 .name = "wakeup",
745 .init = wakeup_tracer_init,
746 .reset = wakeup_tracer_reset,
747 .start = wakeup_tracer_start,
748 .stop = wakeup_tracer_stop,
749 .print_max = true,
750 .print_header = wakeup_print_header,
751 .print_line = wakeup_print_line,
752 .flag_changed = wakeup_flag_changed,
753#ifdef CONFIG_FTRACE_SELFTEST
754 .selftest = trace_selftest_startup_wakeup,
755#endif
756 .open = wakeup_trace_open,
757 .close = wakeup_trace_close,
758 .allow_instances = true,
759 .use_max_tr = true,
760};
761
762static struct tracer wakeup_rt_tracer __read_mostly =
763{
764 .name = "wakeup_rt",
765 .init = wakeup_rt_tracer_init,
766 .reset = wakeup_tracer_reset,
767 .start = wakeup_tracer_start,
768 .stop = wakeup_tracer_stop,
769 .print_max = true,
770 .print_header = wakeup_print_header,
771 .print_line = wakeup_print_line,
772 .flag_changed = wakeup_flag_changed,
773#ifdef CONFIG_FTRACE_SELFTEST
774 .selftest = trace_selftest_startup_wakeup,
775#endif
776 .open = wakeup_trace_open,
777 .close = wakeup_trace_close,
778 .allow_instances = true,
779 .use_max_tr = true,
780};
781
782static struct tracer wakeup_dl_tracer __read_mostly =
783{
784 .name = "wakeup_dl",
785 .init = wakeup_dl_tracer_init,
786 .reset = wakeup_tracer_reset,
787 .start = wakeup_tracer_start,
788 .stop = wakeup_tracer_stop,
789 .print_max = true,
790 .print_header = wakeup_print_header,
791 .print_line = wakeup_print_line,
792 .flag_changed = wakeup_flag_changed,
793#ifdef CONFIG_FTRACE_SELFTEST
794 .selftest = trace_selftest_startup_wakeup,
795#endif
796 .open = wakeup_trace_open,
797 .close = wakeup_trace_close,
798 .allow_instances = true,
799 .use_max_tr = true,
800};
801
802__init static int init_wakeup_tracer(void)
803{
804 int ret;
805
806 ret = register_tracer(type: &wakeup_tracer);
807 if (ret)
808 return ret;
809
810 ret = register_tracer(type: &wakeup_rt_tracer);
811 if (ret)
812 return ret;
813
814 ret = register_tracer(type: &wakeup_dl_tracer);
815 if (ret)
816 return ret;
817
818 return 0;
819}
820core_initcall(init_wakeup_tracer);
821

source code of linux/kernel/trace/trace_sched_wakeup.c