1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _LINUX_SCHED_SIGNAL_H
3#define _LINUX_SCHED_SIGNAL_H
4
5#include <linux/rculist.h>
6#include <linux/signal.h>
7#include <linux/sched.h>
8#include <linux/sched/jobctl.h>
9#include <linux/sched/task.h>
10#include <linux/cred.h>
11#include <linux/refcount.h>
12#include <linux/pid.h>
13#include <linux/posix-timers.h>
14#include <linux/mm_types.h>
15#include <asm/ptrace.h>
16
17/*
18 * Types defining task->signal and task->sighand and APIs using them:
19 */
20
21struct sighand_struct {
22 spinlock_t siglock;
23 refcount_t count;
24 wait_queue_head_t signalfd_wqh;
25 struct k_sigaction action[_NSIG];
26};
27
28/*
29 * Per-process accounting stats:
30 */
31struct pacct_struct {
32 int ac_flag;
33 long ac_exitcode;
34 unsigned long ac_mem;
35 u64 ac_utime, ac_stime;
36 unsigned long ac_minflt, ac_majflt;
37};
38
39struct cpu_itimer {
40 u64 expires;
41 u64 incr;
42};
43
44/*
45 * This is the atomic variant of task_cputime, which can be used for
46 * storing and updating task_cputime statistics without locking.
47 */
48struct task_cputime_atomic {
49 atomic64_t utime;
50 atomic64_t stime;
51 atomic64_t sum_exec_runtime;
52};
53
54#define INIT_CPUTIME_ATOMIC \
55 (struct task_cputime_atomic) { \
56 .utime = ATOMIC64_INIT(0), \
57 .stime = ATOMIC64_INIT(0), \
58 .sum_exec_runtime = ATOMIC64_INIT(0), \
59 }
60/**
61 * struct thread_group_cputimer - thread group interval timer counts
62 * @cputime_atomic: atomic thread group interval timers.
63 *
64 * This structure contains the version of task_cputime, above, that is
65 * used for thread group CPU timer calculations.
66 */
67struct thread_group_cputimer {
68 struct task_cputime_atomic cputime_atomic;
69};
70
71struct multiprocess_signals {
72 sigset_t signal;
73 struct hlist_node node;
74};
75
76struct core_thread {
77 struct task_struct *task;
78 struct core_thread *next;
79};
80
81struct core_state {
82 atomic_t nr_threads;
83 struct core_thread dumper;
84 struct completion startup;
85};
86
87/*
88 * NOTE! "signal_struct" does not have its own
89 * locking, because a shared signal_struct always
90 * implies a shared sighand_struct, so locking
91 * sighand_struct is always a proper superset of
92 * the locking of signal_struct.
93 */
94struct signal_struct {
95 refcount_t sigcnt;
96 atomic_t live;
97 int nr_threads;
98 int quick_threads;
99 struct list_head thread_head;
100
101 wait_queue_head_t wait_chldexit; /* for wait4() */
102
103 /* current thread group signal load-balancing target: */
104 struct task_struct *curr_target;
105
106 /* shared signal handling: */
107 struct sigpending shared_pending;
108
109 /* For collecting multiprocess signals during fork */
110 struct hlist_head multiprocess;
111
112 /* thread group exit support */
113 int group_exit_code;
114 /* notify group_exec_task when notify_count is less or equal to 0 */
115 int notify_count;
116 struct task_struct *group_exec_task;
117
118 /* thread group stop support, overloads group_exit_code too */
119 int group_stop_count;
120 unsigned int flags; /* see SIGNAL_* flags below */
121
122 struct core_state *core_state; /* coredumping support */
123
124 /*
125 * PR_SET_CHILD_SUBREAPER marks a process, like a service
126 * manager, to re-parent orphan (double-forking) child processes
127 * to this process instead of 'init'. The service manager is
128 * able to receive SIGCHLD signals and is able to investigate
129 * the process until it calls wait(). All children of this
130 * process will inherit a flag if they should look for a
131 * child_subreaper process at exit.
132 */
133 unsigned int is_child_subreaper:1;
134 unsigned int has_child_subreaper:1;
135
136#ifdef CONFIG_POSIX_TIMERS
137
138 /* POSIX.1b Interval Timers */
139 unsigned int next_posix_timer_id;
140 struct list_head posix_timers;
141
142 /* ITIMER_REAL timer for the process */
143 struct hrtimer real_timer;
144 ktime_t it_real_incr;
145
146 /*
147 * ITIMER_PROF and ITIMER_VIRTUAL timers for the process, we use
148 * CPUCLOCK_PROF and CPUCLOCK_VIRT for indexing array as these
149 * values are defined to 0 and 1 respectively
150 */
151 struct cpu_itimer it[2];
152
153 /*
154 * Thread group totals for process CPU timers.
155 * See thread_group_cputimer(), et al, for details.
156 */
157 struct thread_group_cputimer cputimer;
158
159#endif
160 /* Empty if CONFIG_POSIX_TIMERS=n */
161 struct posix_cputimers posix_cputimers;
162
163 /* PID/PID hash table linkage. */
164 struct pid *pids[PIDTYPE_MAX];
165
166#ifdef CONFIG_NO_HZ_FULL
167 atomic_t tick_dep_mask;
168#endif
169
170 struct pid *tty_old_pgrp;
171
172 /* boolean value for session group leader */
173 int leader;
174
175 struct tty_struct *tty; /* NULL if no tty */
176
177#ifdef CONFIG_SCHED_AUTOGROUP
178 struct autogroup *autogroup;
179#endif
180 /*
181 * Cumulative resource counters for dead threads in the group,
182 * and for reaped dead child processes forked by this group.
183 * Live threads maintain their own counters and add to these
184 * in __exit_signal, except for the group leader.
185 */
186 seqlock_t stats_lock;
187 u64 utime, stime, cutime, cstime;
188 u64 gtime;
189 u64 cgtime;
190 struct prev_cputime prev_cputime;
191 unsigned long nvcsw, nivcsw, cnvcsw, cnivcsw;
192 unsigned long min_flt, maj_flt, cmin_flt, cmaj_flt;
193 unsigned long inblock, oublock, cinblock, coublock;
194 unsigned long maxrss, cmaxrss;
195 struct task_io_accounting ioac;
196
197 /*
198 * Cumulative ns of schedule CPU time fo dead threads in the
199 * group, not including a zombie group leader, (This only differs
200 * from jiffies_to_ns(utime + stime) if sched_clock uses something
201 * other than jiffies.)
202 */
203 unsigned long long sum_sched_runtime;
204
205 /*
206 * We don't bother to synchronize most readers of this at all,
207 * because there is no reader checking a limit that actually needs
208 * to get both rlim_cur and rlim_max atomically, and either one
209 * alone is a single word that can safely be read normally.
210 * getrlimit/setrlimit use task_lock(current->group_leader) to
211 * protect this instead of the siglock, because they really
212 * have no need to disable irqs.
213 */
214 struct rlimit rlim[RLIM_NLIMITS];
215
216#ifdef CONFIG_BSD_PROCESS_ACCT
217 struct pacct_struct pacct; /* per-process accounting information */
218#endif
219#ifdef CONFIG_TASKSTATS
220 struct taskstats *stats;
221#endif
222#ifdef CONFIG_AUDIT
223 unsigned audit_tty;
224 struct tty_audit_buf *tty_audit_buf;
225#endif
226
227 /*
228 * Thread is the potential origin of an oom condition; kill first on
229 * oom
230 */
231 bool oom_flag_origin;
232 short oom_score_adj; /* OOM kill score adjustment */
233 short oom_score_adj_min; /* OOM kill score adjustment min value.
234 * Only settable by CAP_SYS_RESOURCE. */
235 struct mm_struct *oom_mm; /* recorded mm when the thread group got
236 * killed by the oom killer */
237
238 struct mutex cred_guard_mutex; /* guard against foreign influences on
239 * credential calculations
240 * (notably. ptrace)
241 * Deprecated do not use in new code.
242 * Use exec_update_lock instead.
243 */
244 struct rw_semaphore exec_update_lock; /* Held while task_struct is
245 * being updated during exec,
246 * and may have inconsistent
247 * permissions.
248 */
249} __randomize_layout;
250
251/*
252 * Bits in flags field of signal_struct.
253 */
254#define SIGNAL_STOP_STOPPED 0x00000001 /* job control stop in effect */
255#define SIGNAL_STOP_CONTINUED 0x00000002 /* SIGCONT since WCONTINUED reap */
256#define SIGNAL_GROUP_EXIT 0x00000004 /* group exit in progress */
257/*
258 * Pending notifications to parent.
259 */
260#define SIGNAL_CLD_STOPPED 0x00000010
261#define SIGNAL_CLD_CONTINUED 0x00000020
262#define SIGNAL_CLD_MASK (SIGNAL_CLD_STOPPED|SIGNAL_CLD_CONTINUED)
263
264#define SIGNAL_UNKILLABLE 0x00000040 /* for init: ignore fatal signals */
265
266#define SIGNAL_STOP_MASK (SIGNAL_CLD_MASK | SIGNAL_STOP_STOPPED | \
267 SIGNAL_STOP_CONTINUED)
268
269static inline void signal_set_stop_flags(struct signal_struct *sig,
270 unsigned int flags)
271{
272 WARN_ON(sig->flags & SIGNAL_GROUP_EXIT);
273 sig->flags = (sig->flags & ~SIGNAL_STOP_MASK) | flags;
274}
275
276extern void flush_signals(struct task_struct *);
277extern void ignore_signals(struct task_struct *);
278extern void flush_signal_handlers(struct task_struct *, int force_default);
279extern int dequeue_signal(struct task_struct *task, sigset_t *mask,
280 kernel_siginfo_t *info, enum pid_type *type);
281
282static inline int kernel_dequeue_signal(void)
283{
284 struct task_struct *task = current;
285 kernel_siginfo_t __info;
286 enum pid_type __type;
287 int ret;
288
289 spin_lock_irq(lock: &task->sighand->siglock);
290 ret = dequeue_signal(task, mask: &task->blocked, info: &__info, type: &__type);
291 spin_unlock_irq(lock: &task->sighand->siglock);
292
293 return ret;
294}
295
296static inline void kernel_signal_stop(void)
297{
298 spin_lock_irq(lock: &current->sighand->siglock);
299 if (current->jobctl & JOBCTL_STOP_DEQUEUED) {
300 current->jobctl |= JOBCTL_STOPPED;
301 set_special_state(TASK_STOPPED);
302 }
303 spin_unlock_irq(lock: &current->sighand->siglock);
304
305 schedule();
306}
307
308int force_sig_fault_to_task(int sig, int code, void __user *addr,
309 struct task_struct *t);
310int force_sig_fault(int sig, int code, void __user *addr);
311int send_sig_fault(int sig, int code, void __user *addr, struct task_struct *t);
312
313int force_sig_mceerr(int code, void __user *, short);
314int send_sig_mceerr(int code, void __user *, short, struct task_struct *);
315
316int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper);
317int force_sig_pkuerr(void __user *addr, u32 pkey);
318int send_sig_perf(void __user *addr, u32 type, u64 sig_data);
319
320int force_sig_ptrace_errno_trap(int errno, void __user *addr);
321int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno);
322int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
323 struct task_struct *t);
324int force_sig_seccomp(int syscall, int reason, bool force_coredump);
325
326extern int send_sig_info(int, struct kernel_siginfo *, struct task_struct *);
327extern void force_sigsegv(int sig);
328extern int force_sig_info(struct kernel_siginfo *);
329extern int __kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp);
330extern int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid);
331extern int kill_pid_usb_asyncio(int sig, int errno, sigval_t addr, struct pid *,
332 const struct cred *);
333extern int kill_pgrp(struct pid *pid, int sig, int priv);
334extern int kill_pid(struct pid *pid, int sig, int priv);
335extern __must_check bool do_notify_parent(struct task_struct *, int);
336extern void __wake_up_parent(struct task_struct *p, struct task_struct *parent);
337extern void force_sig(int);
338extern void force_fatal_sig(int);
339extern void force_exit_sig(int);
340extern int send_sig(int, struct task_struct *, int);
341extern int zap_other_threads(struct task_struct *p);
342extern struct sigqueue *sigqueue_alloc(void);
343extern void sigqueue_free(struct sigqueue *);
344extern int send_sigqueue(struct sigqueue *, struct pid *, enum pid_type);
345extern int do_sigaction(int, struct k_sigaction *, struct k_sigaction *);
346
347static inline void clear_notify_signal(void)
348{
349 clear_thread_flag(TIF_NOTIFY_SIGNAL);
350 smp_mb__after_atomic();
351}
352
353/*
354 * Returns 'true' if kick_process() is needed to force a transition from
355 * user -> kernel to guarantee expedient run of TWA_SIGNAL based task_work.
356 */
357static inline bool __set_notify_signal(struct task_struct *task)
358{
359 return !test_and_set_tsk_thread_flag(tsk: task, TIF_NOTIFY_SIGNAL) &&
360 !wake_up_state(tsk: task, TASK_INTERRUPTIBLE);
361}
362
363/*
364 * Called to break out of interruptible wait loops, and enter the
365 * exit_to_user_mode_loop().
366 */
367static inline void set_notify_signal(struct task_struct *task)
368{
369 if (__set_notify_signal(task))
370 kick_process(tsk: task);
371}
372
373static inline int restart_syscall(void)
374{
375 set_tsk_thread_flag(current, TIF_SIGPENDING);
376 return -ERESTARTNOINTR;
377}
378
379static inline int task_sigpending(struct task_struct *p)
380{
381 return unlikely(test_tsk_thread_flag(p,TIF_SIGPENDING));
382}
383
384static inline int signal_pending(struct task_struct *p)
385{
386 /*
387 * TIF_NOTIFY_SIGNAL isn't really a signal, but it requires the same
388 * behavior in terms of ensuring that we break out of wait loops
389 * so that notify signal callbacks can be processed.
390 */
391 if (unlikely(test_tsk_thread_flag(p, TIF_NOTIFY_SIGNAL)))
392 return 1;
393 return task_sigpending(p);
394}
395
396static inline int __fatal_signal_pending(struct task_struct *p)
397{
398 return unlikely(sigismember(&p->pending.signal, SIGKILL));
399}
400
401static inline int fatal_signal_pending(struct task_struct *p)
402{
403 return task_sigpending(p) && __fatal_signal_pending(p);
404}
405
406static inline int signal_pending_state(unsigned int state, struct task_struct *p)
407{
408 if (!(state & (TASK_INTERRUPTIBLE | TASK_WAKEKILL)))
409 return 0;
410 if (!signal_pending(p))
411 return 0;
412
413 return (state & TASK_INTERRUPTIBLE) || __fatal_signal_pending(p);
414}
415
416/*
417 * This should only be used in fault handlers to decide whether we
418 * should stop the current fault routine to handle the signals
419 * instead, especially with the case where we've got interrupted with
420 * a VM_FAULT_RETRY.
421 */
422static inline bool fault_signal_pending(vm_fault_t fault_flags,
423 struct pt_regs *regs)
424{
425 return unlikely((fault_flags & VM_FAULT_RETRY) &&
426 (fatal_signal_pending(current) ||
427 (user_mode(regs) && signal_pending(current))));
428}
429
430/*
431 * Reevaluate whether the task has signals pending delivery.
432 * Wake the task if so.
433 * This is required every time the blocked sigset_t changes.
434 * callers must hold sighand->siglock.
435 */
436extern void recalc_sigpending(void);
437extern void calculate_sigpending(void);
438
439extern void signal_wake_up_state(struct task_struct *t, unsigned int state);
440
441static inline void signal_wake_up(struct task_struct *t, bool fatal)
442{
443 unsigned int state = 0;
444 if (fatal && !(t->jobctl & JOBCTL_PTRACE_FROZEN)) {
445 t->jobctl &= ~(JOBCTL_STOPPED | JOBCTL_TRACED);
446 state = TASK_WAKEKILL | __TASK_TRACED;
447 }
448 signal_wake_up_state(t, state);
449}
450static inline void ptrace_signal_wake_up(struct task_struct *t, bool resume)
451{
452 unsigned int state = 0;
453 if (resume) {
454 t->jobctl &= ~JOBCTL_TRACED;
455 state = __TASK_TRACED;
456 }
457 signal_wake_up_state(t, state);
458}
459
460void task_join_group_stop(struct task_struct *task);
461
462#ifdef TIF_RESTORE_SIGMASK
463/*
464 * Legacy restore_sigmask accessors. These are inefficient on
465 * SMP architectures because they require atomic operations.
466 */
467
468/**
469 * set_restore_sigmask() - make sure saved_sigmask processing gets done
470 *
471 * This sets TIF_RESTORE_SIGMASK and ensures that the arch signal code
472 * will run before returning to user mode, to process the flag. For
473 * all callers, TIF_SIGPENDING is already set or it's no harm to set
474 * it. TIF_RESTORE_SIGMASK need not be in the set of bits that the
475 * arch code will notice on return to user mode, in case those bits
476 * are scarce. We set TIF_SIGPENDING here to ensure that the arch
477 * signal code always gets run when TIF_RESTORE_SIGMASK is set.
478 */
479static inline void set_restore_sigmask(void)
480{
481 set_thread_flag(TIF_RESTORE_SIGMASK);
482}
483
484static inline void clear_tsk_restore_sigmask(struct task_struct *task)
485{
486 clear_tsk_thread_flag(task, TIF_RESTORE_SIGMASK);
487}
488
489static inline void clear_restore_sigmask(void)
490{
491 clear_thread_flag(TIF_RESTORE_SIGMASK);
492}
493static inline bool test_tsk_restore_sigmask(struct task_struct *task)
494{
495 return test_tsk_thread_flag(task, TIF_RESTORE_SIGMASK);
496}
497static inline bool test_restore_sigmask(void)
498{
499 return test_thread_flag(TIF_RESTORE_SIGMASK);
500}
501static inline bool test_and_clear_restore_sigmask(void)
502{
503 return test_and_clear_thread_flag(TIF_RESTORE_SIGMASK);
504}
505
506#else /* TIF_RESTORE_SIGMASK */
507
508/* Higher-quality implementation, used if TIF_RESTORE_SIGMASK doesn't exist. */
509static inline void set_restore_sigmask(void)
510{
511 current->restore_sigmask = true;
512}
513static inline void clear_tsk_restore_sigmask(struct task_struct *task)
514{
515 task->restore_sigmask = false;
516}
517static inline void clear_restore_sigmask(void)
518{
519 current->restore_sigmask = false;
520}
521static inline bool test_restore_sigmask(void)
522{
523 return current->restore_sigmask;
524}
525static inline bool test_tsk_restore_sigmask(struct task_struct *task)
526{
527 return task->restore_sigmask;
528}
529static inline bool test_and_clear_restore_sigmask(void)
530{
531 if (!current->restore_sigmask)
532 return false;
533 current->restore_sigmask = false;
534 return true;
535}
536#endif
537
538static inline void restore_saved_sigmask(void)
539{
540 if (test_and_clear_restore_sigmask())
541 __set_current_blocked(&current->saved_sigmask);
542}
543
544extern int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize);
545
546static inline void restore_saved_sigmask_unless(bool interrupted)
547{
548 if (interrupted)
549 WARN_ON(!signal_pending(current));
550 else
551 restore_saved_sigmask();
552}
553
554static inline sigset_t *sigmask_to_save(void)
555{
556 sigset_t *res = &current->blocked;
557 if (unlikely(test_restore_sigmask()))
558 res = &current->saved_sigmask;
559 return res;
560}
561
562static inline int kill_cad_pid(int sig, int priv)
563{
564 return kill_pid(pid: cad_pid, sig, priv);
565}
566
567/* These can be the second arg to send_sig_info/send_group_sig_info. */
568#define SEND_SIG_NOINFO ((struct kernel_siginfo *) 0)
569#define SEND_SIG_PRIV ((struct kernel_siginfo *) 1)
570
571static inline int __on_sig_stack(unsigned long sp)
572{
573#ifdef CONFIG_STACK_GROWSUP
574 return sp >= current->sas_ss_sp &&
575 sp - current->sas_ss_sp < current->sas_ss_size;
576#else
577 return sp > current->sas_ss_sp &&
578 sp - current->sas_ss_sp <= current->sas_ss_size;
579#endif
580}
581
582/*
583 * True if we are on the alternate signal stack.
584 */
585static inline int on_sig_stack(unsigned long sp)
586{
587 /*
588 * If the signal stack is SS_AUTODISARM then, by construction, we
589 * can't be on the signal stack unless user code deliberately set
590 * SS_AUTODISARM when we were already on it.
591 *
592 * This improves reliability: if user state gets corrupted such that
593 * the stack pointer points very close to the end of the signal stack,
594 * then this check will enable the signal to be handled anyway.
595 */
596 if (current->sas_ss_flags & SS_AUTODISARM)
597 return 0;
598
599 return __on_sig_stack(sp);
600}
601
602static inline int sas_ss_flags(unsigned long sp)
603{
604 if (!current->sas_ss_size)
605 return SS_DISABLE;
606
607 return on_sig_stack(sp) ? SS_ONSTACK : 0;
608}
609
610static inline void sas_ss_reset(struct task_struct *p)
611{
612 p->sas_ss_sp = 0;
613 p->sas_ss_size = 0;
614 p->sas_ss_flags = SS_DISABLE;
615}
616
617static inline unsigned long sigsp(unsigned long sp, struct ksignal *ksig)
618{
619 if (unlikely((ksig->ka.sa.sa_flags & SA_ONSTACK)) && ! sas_ss_flags(sp))
620#ifdef CONFIG_STACK_GROWSUP
621 return current->sas_ss_sp;
622#else
623 return current->sas_ss_sp + current->sas_ss_size;
624#endif
625 return sp;
626}
627
628extern void __cleanup_sighand(struct sighand_struct *);
629extern void flush_itimer_signals(void);
630
631#define tasklist_empty() \
632 list_empty(&init_task.tasks)
633
634#define next_task(p) \
635 list_entry_rcu((p)->tasks.next, struct task_struct, tasks)
636
637#define for_each_process(p) \
638 for (p = &init_task ; (p = next_task(p)) != &init_task ; )
639
640extern bool current_is_single_threaded(void);
641
642/*
643 * Without tasklist/siglock it is only rcu-safe if g can't exit/exec,
644 * otherwise next_thread(t) will never reach g after list_del_rcu(g).
645 */
646#define while_each_thread(g, t) \
647 while ((t = next_thread(t)) != g)
648
649#define for_other_threads(p, t) \
650 for (t = p; (t = next_thread(t)) != p; )
651
652#define __for_each_thread(signal, t) \
653 list_for_each_entry_rcu(t, &(signal)->thread_head, thread_node, \
654 lockdep_is_held(&tasklist_lock))
655
656#define for_each_thread(p, t) \
657 __for_each_thread((p)->signal, t)
658
659/* Careful: this is a double loop, 'break' won't work as expected. */
660#define for_each_process_thread(p, t) \
661 for_each_process(p) for_each_thread(p, t)
662
663typedef int (*proc_visitor)(struct task_struct *p, void *data);
664void walk_process_tree(struct task_struct *top, proc_visitor, void *);
665
666static inline
667struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
668{
669 struct pid *pid;
670 if (type == PIDTYPE_PID)
671 pid = task_pid(task);
672 else
673 pid = task->signal->pids[type];
674 return pid;
675}
676
677static inline struct pid *task_tgid(struct task_struct *task)
678{
679 return task->signal->pids[PIDTYPE_TGID];
680}
681
682/*
683 * Without tasklist or RCU lock it is not safe to dereference
684 * the result of task_pgrp/task_session even if task == current,
685 * we can race with another thread doing sys_setsid/sys_setpgid.
686 */
687static inline struct pid *task_pgrp(struct task_struct *task)
688{
689 return task->signal->pids[PIDTYPE_PGID];
690}
691
692static inline struct pid *task_session(struct task_struct *task)
693{
694 return task->signal->pids[PIDTYPE_SID];
695}
696
697static inline int get_nr_threads(struct task_struct *task)
698{
699 return task->signal->nr_threads;
700}
701
702static inline bool thread_group_leader(struct task_struct *p)
703{
704 return p->exit_signal >= 0;
705}
706
707static inline
708bool same_thread_group(struct task_struct *p1, struct task_struct *p2)
709{
710 return p1->signal == p2->signal;
711}
712
713/*
714 * returns NULL if p is the last thread in the thread group
715 */
716static inline struct task_struct *__next_thread(struct task_struct *p)
717{
718 return list_next_or_null_rcu(&p->signal->thread_head,
719 &p->thread_node,
720 struct task_struct,
721 thread_node);
722}
723
724static inline struct task_struct *next_thread(struct task_struct *p)
725{
726 return __next_thread(p) ?: p->group_leader;
727}
728
729static inline int thread_group_empty(struct task_struct *p)
730{
731 return thread_group_leader(p) &&
732 list_is_last(list: &p->thread_node, head: &p->signal->thread_head);
733}
734
735#define delay_group_leader(p) \
736 (thread_group_leader(p) && !thread_group_empty(p))
737
738extern struct sighand_struct *__lock_task_sighand(struct task_struct *task,
739 unsigned long *flags);
740
741static inline struct sighand_struct *lock_task_sighand(struct task_struct *task,
742 unsigned long *flags)
743{
744 struct sighand_struct *ret;
745
746 ret = __lock_task_sighand(task, flags);
747 (void)__cond_lock(&task->sighand->siglock, ret);
748 return ret;
749}
750
751static inline void unlock_task_sighand(struct task_struct *task,
752 unsigned long *flags)
753{
754 spin_unlock_irqrestore(lock: &task->sighand->siglock, flags: *flags);
755}
756
757#ifdef CONFIG_LOCKDEP
758extern void lockdep_assert_task_sighand_held(struct task_struct *task);
759#else
760static inline void lockdep_assert_task_sighand_held(struct task_struct *task) { }
761#endif
762
763static inline unsigned long task_rlimit(const struct task_struct *task,
764 unsigned int limit)
765{
766 return READ_ONCE(task->signal->rlim[limit].rlim_cur);
767}
768
769static inline unsigned long task_rlimit_max(const struct task_struct *task,
770 unsigned int limit)
771{
772 return READ_ONCE(task->signal->rlim[limit].rlim_max);
773}
774
775static inline unsigned long rlimit(unsigned int limit)
776{
777 return task_rlimit(current, limit);
778}
779
780static inline unsigned long rlimit_max(unsigned int limit)
781{
782 return task_rlimit_max(current, limit);
783}
784
785#endif /* _LINUX_SCHED_SIGNAL_H */
786

source code of linux/include/linux/sched/signal.h