xref: /linux/include/linux/sched/signal.h (revision 5e0266f0e5f57617472d5aac4013f58a3ef264ac)
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/posix-timers.h>
13 #include <linux/mm_types.h>
14 #include <asm/ptrace.h>
15 
16 /*
17  * Types defining task->signal and task->sighand and APIs using them:
18  */
19 
20 struct sighand_struct {
21 	spinlock_t		siglock;
22 	refcount_t		count;
23 	wait_queue_head_t	signalfd_wqh;
24 	struct k_sigaction	action[_NSIG];
25 };
26 
27 /*
28  * Per-process accounting stats:
29  */
30 struct pacct_struct {
31 	int			ac_flag;
32 	long			ac_exitcode;
33 	unsigned long		ac_mem;
34 	u64			ac_utime, ac_stime;
35 	unsigned long		ac_minflt, ac_majflt;
36 };
37 
38 struct cpu_itimer {
39 	u64 expires;
40 	u64 incr;
41 };
42 
43 /*
44  * This is the atomic variant of task_cputime, which can be used for
45  * storing and updating task_cputime statistics without locking.
46  */
47 struct task_cputime_atomic {
48 	atomic64_t utime;
49 	atomic64_t stime;
50 	atomic64_t sum_exec_runtime;
51 };
52 
53 #define INIT_CPUTIME_ATOMIC \
54 	(struct task_cputime_atomic) {				\
55 		.utime = ATOMIC64_INIT(0),			\
56 		.stime = ATOMIC64_INIT(0),			\
57 		.sum_exec_runtime = ATOMIC64_INIT(0),		\
58 	}
59 /**
60  * struct thread_group_cputimer - thread group interval timer counts
61  * @cputime_atomic:	atomic thread group interval timers.
62  *
63  * This structure contains the version of task_cputime, above, that is
64  * used for thread group CPU timer calculations.
65  */
66 struct thread_group_cputimer {
67 	struct task_cputime_atomic cputime_atomic;
68 };
69 
70 struct multiprocess_signals {
71 	sigset_t signal;
72 	struct hlist_node node;
73 };
74 
75 struct core_thread {
76 	struct task_struct *task;
77 	struct core_thread *next;
78 };
79 
80 struct core_state {
81 	atomic_t nr_threads;
82 	struct core_thread dumper;
83 	struct completion startup;
84 };
85 
86 /*
87  * NOTE! "signal_struct" does not have its own
88  * locking, because a shared signal_struct always
89  * implies a shared sighand_struct, so locking
90  * sighand_struct is always a proper superset of
91  * the locking of signal_struct.
92  */
93 struct signal_struct {
94 	refcount_t		sigcnt;
95 	atomic_t		live;
96 	int			nr_threads;
97 	int			quick_threads;
98 	struct list_head	thread_head;
99 
100 	wait_queue_head_t	wait_chldexit;	/* for wait4() */
101 
102 	/* current thread group signal load-balancing target: */
103 	struct task_struct	*curr_target;
104 
105 	/* shared signal handling: */
106 	struct sigpending	shared_pending;
107 
108 	/* For collecting multiprocess signals during fork */
109 	struct hlist_head	multiprocess;
110 
111 	/* thread group exit support */
112 	int			group_exit_code;
113 	/* notify group_exec_task when notify_count is less or equal to 0 */
114 	int			notify_count;
115 	struct task_struct	*group_exec_task;
116 
117 	/* thread group stop support, overloads group_exit_code too */
118 	int			group_stop_count;
119 	unsigned int		flags; /* see SIGNAL_* flags below */
120 
121 	struct core_state *core_state; /* coredumping support */
122 
123 	/*
124 	 * PR_SET_CHILD_SUBREAPER marks a process, like a service
125 	 * manager, to re-parent orphan (double-forking) child processes
126 	 * to this process instead of 'init'. The service manager is
127 	 * able to receive SIGCHLD signals and is able to investigate
128 	 * the process until it calls wait(). All children of this
129 	 * process will inherit a flag if they should look for a
130 	 * child_subreaper process at exit.
131 	 */
132 	unsigned int		is_child_subreaper:1;
133 	unsigned int		has_child_subreaper:1;
134 
135 #ifdef CONFIG_POSIX_TIMERS
136 
137 	/* POSIX.1b Interval Timers */
138 	int			posix_timer_id;
139 	struct list_head	posix_timers;
140 
141 	/* ITIMER_REAL timer for the process */
142 	struct hrtimer real_timer;
143 	ktime_t it_real_incr;
144 
145 	/*
146 	 * ITIMER_PROF and ITIMER_VIRTUAL timers for the process, we use
147 	 * CPUCLOCK_PROF and CPUCLOCK_VIRT for indexing array as these
148 	 * values are defined to 0 and 1 respectively
149 	 */
150 	struct cpu_itimer it[2];
151 
152 	/*
153 	 * Thread group totals for process CPU timers.
154 	 * See thread_group_cputimer(), et al, for details.
155 	 */
156 	struct thread_group_cputimer cputimer;
157 
158 #endif
159 	/* Empty if CONFIG_POSIX_TIMERS=n */
160 	struct posix_cputimers posix_cputimers;
161 
162 	/* PID/PID hash table linkage. */
163 	struct pid *pids[PIDTYPE_MAX];
164 
165 #ifdef CONFIG_NO_HZ_FULL
166 	atomic_t tick_dep_mask;
167 #endif
168 
169 	struct pid *tty_old_pgrp;
170 
171 	/* boolean value for session group leader */
172 	int leader;
173 
174 	struct tty_struct *tty; /* NULL if no tty */
175 
176 #ifdef CONFIG_SCHED_AUTOGROUP
177 	struct autogroup *autogroup;
178 #endif
179 	/*
180 	 * Cumulative resource counters for dead threads in the group,
181 	 * and for reaped dead child processes forked by this group.
182 	 * Live threads maintain their own counters and add to these
183 	 * in __exit_signal, except for the group leader.
184 	 */
185 	seqlock_t stats_lock;
186 	u64 utime, stime, cutime, cstime;
187 	u64 gtime;
188 	u64 cgtime;
189 	struct prev_cputime prev_cputime;
190 	unsigned long nvcsw, nivcsw, cnvcsw, cnivcsw;
191 	unsigned long min_flt, maj_flt, cmin_flt, cmaj_flt;
192 	unsigned long inblock, oublock, cinblock, coublock;
193 	unsigned long maxrss, cmaxrss;
194 	struct task_io_accounting ioac;
195 
196 	/*
197 	 * Cumulative ns of schedule CPU time fo dead threads in the
198 	 * group, not including a zombie group leader, (This only differs
199 	 * from jiffies_to_ns(utime + stime) if sched_clock uses something
200 	 * other than jiffies.)
201 	 */
202 	unsigned long long sum_sched_runtime;
203 
204 	/*
205 	 * We don't bother to synchronize most readers of this at all,
206 	 * because there is no reader checking a limit that actually needs
207 	 * to get both rlim_cur and rlim_max atomically, and either one
208 	 * alone is a single word that can safely be read normally.
209 	 * getrlimit/setrlimit use task_lock(current->group_leader) to
210 	 * protect this instead of the siglock, because they really
211 	 * have no need to disable irqs.
212 	 */
213 	struct rlimit rlim[RLIM_NLIMITS];
214 
215 #ifdef CONFIG_BSD_PROCESS_ACCT
216 	struct pacct_struct pacct;	/* per-process accounting information */
217 #endif
218 #ifdef CONFIG_TASKSTATS
219 	struct taskstats *stats;
220 #endif
221 #ifdef CONFIG_AUDIT
222 	unsigned audit_tty;
223 	struct tty_audit_buf *tty_audit_buf;
224 #endif
225 
226 	/*
227 	 * Thread is the potential origin of an oom condition; kill first on
228 	 * oom
229 	 */
230 	bool oom_flag_origin;
231 	short oom_score_adj;		/* OOM kill score adjustment */
232 	short oom_score_adj_min;	/* OOM kill score adjustment min value.
233 					 * Only settable by CAP_SYS_RESOURCE. */
234 	struct mm_struct *oom_mm;	/* recorded mm when the thread group got
235 					 * killed by the oom killer */
236 
237 	struct mutex cred_guard_mutex;	/* guard against foreign influences on
238 					 * credential calculations
239 					 * (notably. ptrace)
240 					 * Deprecated do not use in new code.
241 					 * Use exec_update_lock instead.
242 					 */
243 	struct rw_semaphore exec_update_lock;	/* Held while task_struct is
244 						 * being updated during exec,
245 						 * and may have inconsistent
246 						 * permissions.
247 						 */
248 } __randomize_layout;
249 
250 /*
251  * Bits in flags field of signal_struct.
252  */
253 #define SIGNAL_STOP_STOPPED	0x00000001 /* job control stop in effect */
254 #define SIGNAL_STOP_CONTINUED	0x00000002 /* SIGCONT since WCONTINUED reap */
255 #define SIGNAL_GROUP_EXIT	0x00000004 /* group exit in progress */
256 /*
257  * Pending notifications to parent.
258  */
259 #define SIGNAL_CLD_STOPPED	0x00000010
260 #define SIGNAL_CLD_CONTINUED	0x00000020
261 #define SIGNAL_CLD_MASK		(SIGNAL_CLD_STOPPED|SIGNAL_CLD_CONTINUED)
262 
263 #define SIGNAL_UNKILLABLE	0x00000040 /* for init: ignore fatal signals */
264 
265 #define SIGNAL_STOP_MASK (SIGNAL_CLD_MASK | SIGNAL_STOP_STOPPED | \
266 			  SIGNAL_STOP_CONTINUED)
267 
268 static inline void signal_set_stop_flags(struct signal_struct *sig,
269 					 unsigned int flags)
270 {
271 	WARN_ON(sig->flags & SIGNAL_GROUP_EXIT);
272 	sig->flags = (sig->flags & ~SIGNAL_STOP_MASK) | flags;
273 }
274 
275 extern void flush_signals(struct task_struct *);
276 extern void ignore_signals(struct task_struct *);
277 extern void flush_signal_handlers(struct task_struct *, int force_default);
278 extern int dequeue_signal(struct task_struct *task, sigset_t *mask,
279 			  kernel_siginfo_t *info, enum pid_type *type);
280 
281 static inline int kernel_dequeue_signal(void)
282 {
283 	struct task_struct *task = current;
284 	kernel_siginfo_t __info;
285 	enum pid_type __type;
286 	int ret;
287 
288 	spin_lock_irq(&task->sighand->siglock);
289 	ret = dequeue_signal(task, &task->blocked, &__info, &__type);
290 	spin_unlock_irq(&task->sighand->siglock);
291 
292 	return ret;
293 }
294 
295 static inline void kernel_signal_stop(void)
296 {
297 	spin_lock_irq(&current->sighand->siglock);
298 	if (current->jobctl & JOBCTL_STOP_DEQUEUED) {
299 		current->jobctl |= JOBCTL_STOPPED;
300 		set_special_state(TASK_STOPPED);
301 	}
302 	spin_unlock_irq(&current->sighand->siglock);
303 
304 	schedule();
305 }
306 #ifdef __ia64__
307 # define ___ARCH_SI_IA64(_a1, _a2, _a3) , _a1, _a2, _a3
308 #else
309 # define ___ARCH_SI_IA64(_a1, _a2, _a3)
310 #endif
311 
312 int force_sig_fault_to_task(int sig, int code, void __user *addr
313 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
314 	, struct task_struct *t);
315 int force_sig_fault(int sig, int code, void __user *addr
316 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr));
317 int send_sig_fault(int sig, int code, void __user *addr
318 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
319 	, struct task_struct *t);
320 
321 int force_sig_mceerr(int code, void __user *, short);
322 int send_sig_mceerr(int code, void __user *, short, struct task_struct *);
323 
324 int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper);
325 int force_sig_pkuerr(void __user *addr, u32 pkey);
326 int send_sig_perf(void __user *addr, u32 type, u64 sig_data);
327 
328 int force_sig_ptrace_errno_trap(int errno, void __user *addr);
329 int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno);
330 int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
331 			struct task_struct *t);
332 int force_sig_seccomp(int syscall, int reason, bool force_coredump);
333 
334 extern int send_sig_info(int, struct kernel_siginfo *, struct task_struct *);
335 extern void force_sigsegv(int sig);
336 extern int force_sig_info(struct kernel_siginfo *);
337 extern int __kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp);
338 extern int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid);
339 extern int kill_pid_usb_asyncio(int sig, int errno, sigval_t addr, struct pid *,
340 				const struct cred *);
341 extern int kill_pgrp(struct pid *pid, int sig, int priv);
342 extern int kill_pid(struct pid *pid, int sig, int priv);
343 extern __must_check bool do_notify_parent(struct task_struct *, int);
344 extern void __wake_up_parent(struct task_struct *p, struct task_struct *parent);
345 extern void force_sig(int);
346 extern void force_fatal_sig(int);
347 extern void force_exit_sig(int);
348 extern int send_sig(int, struct task_struct *, int);
349 extern int zap_other_threads(struct task_struct *p);
350 extern struct sigqueue *sigqueue_alloc(void);
351 extern void sigqueue_free(struct sigqueue *);
352 extern int send_sigqueue(struct sigqueue *, struct pid *, enum pid_type);
353 extern int do_sigaction(int, struct k_sigaction *, struct k_sigaction *);
354 
355 static inline void clear_notify_signal(void)
356 {
357 	clear_thread_flag(TIF_NOTIFY_SIGNAL);
358 	smp_mb__after_atomic();
359 }
360 
361 /*
362  * Returns 'true' if kick_process() is needed to force a transition from
363  * user -> kernel to guarantee expedient run of TWA_SIGNAL based task_work.
364  */
365 static inline bool __set_notify_signal(struct task_struct *task)
366 {
367 	return !test_and_set_tsk_thread_flag(task, TIF_NOTIFY_SIGNAL) &&
368 	       !wake_up_state(task, TASK_INTERRUPTIBLE);
369 }
370 
371 /*
372  * Called to break out of interruptible wait loops, and enter the
373  * exit_to_user_mode_loop().
374  */
375 static inline void set_notify_signal(struct task_struct *task)
376 {
377 	if (__set_notify_signal(task))
378 		kick_process(task);
379 }
380 
381 static inline int restart_syscall(void)
382 {
383 	set_tsk_thread_flag(current, TIF_SIGPENDING);
384 	return -ERESTARTNOINTR;
385 }
386 
387 static inline int task_sigpending(struct task_struct *p)
388 {
389 	return unlikely(test_tsk_thread_flag(p,TIF_SIGPENDING));
390 }
391 
392 static inline int signal_pending(struct task_struct *p)
393 {
394 	/*
395 	 * TIF_NOTIFY_SIGNAL isn't really a signal, but it requires the same
396 	 * behavior in terms of ensuring that we break out of wait loops
397 	 * so that notify signal callbacks can be processed.
398 	 */
399 	if (unlikely(test_tsk_thread_flag(p, TIF_NOTIFY_SIGNAL)))
400 		return 1;
401 	return task_sigpending(p);
402 }
403 
404 static inline int __fatal_signal_pending(struct task_struct *p)
405 {
406 	return unlikely(sigismember(&p->pending.signal, SIGKILL));
407 }
408 
409 static inline int fatal_signal_pending(struct task_struct *p)
410 {
411 	return task_sigpending(p) && __fatal_signal_pending(p);
412 }
413 
414 static inline int signal_pending_state(unsigned int state, struct task_struct *p)
415 {
416 	if (!(state & (TASK_INTERRUPTIBLE | TASK_WAKEKILL)))
417 		return 0;
418 	if (!signal_pending(p))
419 		return 0;
420 
421 	return (state & TASK_INTERRUPTIBLE) || __fatal_signal_pending(p);
422 }
423 
424 /*
425  * This should only be used in fault handlers to decide whether we
426  * should stop the current fault routine to handle the signals
427  * instead, especially with the case where we've got interrupted with
428  * a VM_FAULT_RETRY.
429  */
430 static inline bool fault_signal_pending(vm_fault_t fault_flags,
431 					struct pt_regs *regs)
432 {
433 	return unlikely((fault_flags & VM_FAULT_RETRY) &&
434 			(fatal_signal_pending(current) ||
435 			 (user_mode(regs) && signal_pending(current))));
436 }
437 
438 /*
439  * Reevaluate whether the task has signals pending delivery.
440  * Wake the task if so.
441  * This is required every time the blocked sigset_t changes.
442  * callers must hold sighand->siglock.
443  */
444 extern void recalc_sigpending_and_wake(struct task_struct *t);
445 extern void recalc_sigpending(void);
446 extern void calculate_sigpending(void);
447 
448 extern void signal_wake_up_state(struct task_struct *t, unsigned int state);
449 
450 static inline void signal_wake_up(struct task_struct *t, bool fatal)
451 {
452 	unsigned int state = 0;
453 	if (fatal && !(t->jobctl & JOBCTL_PTRACE_FROZEN)) {
454 		t->jobctl &= ~(JOBCTL_STOPPED | JOBCTL_TRACED);
455 		state = TASK_WAKEKILL | __TASK_TRACED;
456 	}
457 	signal_wake_up_state(t, state);
458 }
459 static inline void ptrace_signal_wake_up(struct task_struct *t, bool resume)
460 {
461 	unsigned int state = 0;
462 	if (resume) {
463 		t->jobctl &= ~JOBCTL_TRACED;
464 		state = __TASK_TRACED;
465 	}
466 	signal_wake_up_state(t, state);
467 }
468 
469 void task_join_group_stop(struct task_struct *task);
470 
471 #ifdef TIF_RESTORE_SIGMASK
472 /*
473  * Legacy restore_sigmask accessors.  These are inefficient on
474  * SMP architectures because they require atomic operations.
475  */
476 
477 /**
478  * set_restore_sigmask() - make sure saved_sigmask processing gets done
479  *
480  * This sets TIF_RESTORE_SIGMASK and ensures that the arch signal code
481  * will run before returning to user mode, to process the flag.  For
482  * all callers, TIF_SIGPENDING is already set or it's no harm to set
483  * it.  TIF_RESTORE_SIGMASK need not be in the set of bits that the
484  * arch code will notice on return to user mode, in case those bits
485  * are scarce.  We set TIF_SIGPENDING here to ensure that the arch
486  * signal code always gets run when TIF_RESTORE_SIGMASK is set.
487  */
488 static inline void set_restore_sigmask(void)
489 {
490 	set_thread_flag(TIF_RESTORE_SIGMASK);
491 }
492 
493 static inline void clear_tsk_restore_sigmask(struct task_struct *task)
494 {
495 	clear_tsk_thread_flag(task, TIF_RESTORE_SIGMASK);
496 }
497 
498 static inline void clear_restore_sigmask(void)
499 {
500 	clear_thread_flag(TIF_RESTORE_SIGMASK);
501 }
502 static inline bool test_tsk_restore_sigmask(struct task_struct *task)
503 {
504 	return test_tsk_thread_flag(task, TIF_RESTORE_SIGMASK);
505 }
506 static inline bool test_restore_sigmask(void)
507 {
508 	return test_thread_flag(TIF_RESTORE_SIGMASK);
509 }
510 static inline bool test_and_clear_restore_sigmask(void)
511 {
512 	return test_and_clear_thread_flag(TIF_RESTORE_SIGMASK);
513 }
514 
515 #else	/* TIF_RESTORE_SIGMASK */
516 
517 /* Higher-quality implementation, used if TIF_RESTORE_SIGMASK doesn't exist. */
518 static inline void set_restore_sigmask(void)
519 {
520 	current->restore_sigmask = true;
521 }
522 static inline void clear_tsk_restore_sigmask(struct task_struct *task)
523 {
524 	task->restore_sigmask = false;
525 }
526 static inline void clear_restore_sigmask(void)
527 {
528 	current->restore_sigmask = false;
529 }
530 static inline bool test_restore_sigmask(void)
531 {
532 	return current->restore_sigmask;
533 }
534 static inline bool test_tsk_restore_sigmask(struct task_struct *task)
535 {
536 	return task->restore_sigmask;
537 }
538 static inline bool test_and_clear_restore_sigmask(void)
539 {
540 	if (!current->restore_sigmask)
541 		return false;
542 	current->restore_sigmask = false;
543 	return true;
544 }
545 #endif
546 
547 static inline void restore_saved_sigmask(void)
548 {
549 	if (test_and_clear_restore_sigmask())
550 		__set_current_blocked(&current->saved_sigmask);
551 }
552 
553 extern int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize);
554 
555 static inline void restore_saved_sigmask_unless(bool interrupted)
556 {
557 	if (interrupted)
558 		WARN_ON(!signal_pending(current));
559 	else
560 		restore_saved_sigmask();
561 }
562 
563 static inline sigset_t *sigmask_to_save(void)
564 {
565 	sigset_t *res = &current->blocked;
566 	if (unlikely(test_restore_sigmask()))
567 		res = &current->saved_sigmask;
568 	return res;
569 }
570 
571 static inline int kill_cad_pid(int sig, int priv)
572 {
573 	return kill_pid(cad_pid, sig, priv);
574 }
575 
576 /* These can be the second arg to send_sig_info/send_group_sig_info.  */
577 #define SEND_SIG_NOINFO ((struct kernel_siginfo *) 0)
578 #define SEND_SIG_PRIV	((struct kernel_siginfo *) 1)
579 
580 static inline int __on_sig_stack(unsigned long sp)
581 {
582 #ifdef CONFIG_STACK_GROWSUP
583 	return sp >= current->sas_ss_sp &&
584 		sp - current->sas_ss_sp < current->sas_ss_size;
585 #else
586 	return sp > current->sas_ss_sp &&
587 		sp - current->sas_ss_sp <= current->sas_ss_size;
588 #endif
589 }
590 
591 /*
592  * True if we are on the alternate signal stack.
593  */
594 static inline int on_sig_stack(unsigned long sp)
595 {
596 	/*
597 	 * If the signal stack is SS_AUTODISARM then, by construction, we
598 	 * can't be on the signal stack unless user code deliberately set
599 	 * SS_AUTODISARM when we were already on it.
600 	 *
601 	 * This improves reliability: if user state gets corrupted such that
602 	 * the stack pointer points very close to the end of the signal stack,
603 	 * then this check will enable the signal to be handled anyway.
604 	 */
605 	if (current->sas_ss_flags & SS_AUTODISARM)
606 		return 0;
607 
608 	return __on_sig_stack(sp);
609 }
610 
611 static inline int sas_ss_flags(unsigned long sp)
612 {
613 	if (!current->sas_ss_size)
614 		return SS_DISABLE;
615 
616 	return on_sig_stack(sp) ? SS_ONSTACK : 0;
617 }
618 
619 static inline void sas_ss_reset(struct task_struct *p)
620 {
621 	p->sas_ss_sp = 0;
622 	p->sas_ss_size = 0;
623 	p->sas_ss_flags = SS_DISABLE;
624 }
625 
626 static inline unsigned long sigsp(unsigned long sp, struct ksignal *ksig)
627 {
628 	if (unlikely((ksig->ka.sa.sa_flags & SA_ONSTACK)) && ! sas_ss_flags(sp))
629 #ifdef CONFIG_STACK_GROWSUP
630 		return current->sas_ss_sp;
631 #else
632 		return current->sas_ss_sp + current->sas_ss_size;
633 #endif
634 	return sp;
635 }
636 
637 extern void __cleanup_sighand(struct sighand_struct *);
638 extern void flush_itimer_signals(void);
639 
640 #define tasklist_empty() \
641 	list_empty(&init_task.tasks)
642 
643 #define next_task(p) \
644 	list_entry_rcu((p)->tasks.next, struct task_struct, tasks)
645 
646 #define for_each_process(p) \
647 	for (p = &init_task ; (p = next_task(p)) != &init_task ; )
648 
649 extern bool current_is_single_threaded(void);
650 
651 /*
652  * Careful: do_each_thread/while_each_thread is a double loop so
653  *          'break' will not work as expected - use goto instead.
654  */
655 #define do_each_thread(g, t) \
656 	for (g = t = &init_task ; (g = t = next_task(g)) != &init_task ; ) do
657 
658 #define while_each_thread(g, t) \
659 	while ((t = next_thread(t)) != g)
660 
661 #define __for_each_thread(signal, t)	\
662 	list_for_each_entry_rcu(t, &(signal)->thread_head, thread_node)
663 
664 #define for_each_thread(p, t)		\
665 	__for_each_thread((p)->signal, t)
666 
667 /* Careful: this is a double loop, 'break' won't work as expected. */
668 #define for_each_process_thread(p, t)	\
669 	for_each_process(p) for_each_thread(p, t)
670 
671 typedef int (*proc_visitor)(struct task_struct *p, void *data);
672 void walk_process_tree(struct task_struct *top, proc_visitor, void *);
673 
674 static inline
675 struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
676 {
677 	struct pid *pid;
678 	if (type == PIDTYPE_PID)
679 		pid = task_pid(task);
680 	else
681 		pid = task->signal->pids[type];
682 	return pid;
683 }
684 
685 static inline struct pid *task_tgid(struct task_struct *task)
686 {
687 	return task->signal->pids[PIDTYPE_TGID];
688 }
689 
690 /*
691  * Without tasklist or RCU lock it is not safe to dereference
692  * the result of task_pgrp/task_session even if task == current,
693  * we can race with another thread doing sys_setsid/sys_setpgid.
694  */
695 static inline struct pid *task_pgrp(struct task_struct *task)
696 {
697 	return task->signal->pids[PIDTYPE_PGID];
698 }
699 
700 static inline struct pid *task_session(struct task_struct *task)
701 {
702 	return task->signal->pids[PIDTYPE_SID];
703 }
704 
705 static inline int get_nr_threads(struct task_struct *task)
706 {
707 	return task->signal->nr_threads;
708 }
709 
710 static inline bool thread_group_leader(struct task_struct *p)
711 {
712 	return p->exit_signal >= 0;
713 }
714 
715 static inline
716 bool same_thread_group(struct task_struct *p1, struct task_struct *p2)
717 {
718 	return p1->signal == p2->signal;
719 }
720 
721 static inline struct task_struct *next_thread(const struct task_struct *p)
722 {
723 	return list_entry_rcu(p->thread_group.next,
724 			      struct task_struct, thread_group);
725 }
726 
727 static inline int thread_group_empty(struct task_struct *p)
728 {
729 	return list_empty(&p->thread_group);
730 }
731 
732 #define delay_group_leader(p) \
733 		(thread_group_leader(p) && !thread_group_empty(p))
734 
735 extern bool thread_group_exited(struct pid *pid);
736 
737 extern struct sighand_struct *__lock_task_sighand(struct task_struct *task,
738 							unsigned long *flags);
739 
740 static inline struct sighand_struct *lock_task_sighand(struct task_struct *task,
741 						       unsigned long *flags)
742 {
743 	struct sighand_struct *ret;
744 
745 	ret = __lock_task_sighand(task, flags);
746 	(void)__cond_lock(&task->sighand->siglock, ret);
747 	return ret;
748 }
749 
750 static inline void unlock_task_sighand(struct task_struct *task,
751 						unsigned long *flags)
752 {
753 	spin_unlock_irqrestore(&task->sighand->siglock, *flags);
754 }
755 
756 #ifdef CONFIG_LOCKDEP
757 extern void lockdep_assert_task_sighand_held(struct task_struct *task);
758 #else
759 static inline void lockdep_assert_task_sighand_held(struct task_struct *task) { }
760 #endif
761 
762 static inline unsigned long task_rlimit(const struct task_struct *task,
763 		unsigned int limit)
764 {
765 	return READ_ONCE(task->signal->rlim[limit].rlim_cur);
766 }
767 
768 static inline unsigned long task_rlimit_max(const struct task_struct *task,
769 		unsigned int limit)
770 {
771 	return READ_ONCE(task->signal->rlim[limit].rlim_max);
772 }
773 
774 static inline unsigned long rlimit(unsigned int limit)
775 {
776 	return task_rlimit(current, limit);
777 }
778 
779 static inline unsigned long rlimit_max(unsigned int limit)
780 {
781 	return task_rlimit_max(current, limit);
782 }
783 
784 #endif /* _LINUX_SCHED_SIGNAL_H */
785