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 
12 /*
13  * Types defining task->signal and task->sighand and APIs using them:
14  */
15 
16 struct sighand_struct {
17 	atomic_t		count;
18 	struct k_sigaction	action[_NSIG];
19 	spinlock_t		siglock;
20 	wait_queue_head_t	signalfd_wqh;
21 };
22 
23 /*
24  * Per-process accounting stats:
25  */
26 struct pacct_struct {
27 	int			ac_flag;
28 	long			ac_exitcode;
29 	unsigned long		ac_mem;
30 	u64			ac_utime, ac_stime;
31 	unsigned long		ac_minflt, ac_majflt;
32 };
33 
34 struct cpu_itimer {
35 	u64 expires;
36 	u64 incr;
37 };
38 
39 /*
40  * This is the atomic variant of task_cputime, which can be used for
41  * storing and updating task_cputime statistics without locking.
42  */
43 struct task_cputime_atomic {
44 	atomic64_t utime;
45 	atomic64_t stime;
46 	atomic64_t sum_exec_runtime;
47 };
48 
49 #define INIT_CPUTIME_ATOMIC \
50 	(struct task_cputime_atomic) {				\
51 		.utime = ATOMIC64_INIT(0),			\
52 		.stime = ATOMIC64_INIT(0),			\
53 		.sum_exec_runtime = ATOMIC64_INIT(0),		\
54 	}
55 /**
56  * struct thread_group_cputimer - thread group interval timer counts
57  * @cputime_atomic:	atomic thread group interval timers.
58  * @running:		true when there are timers running and
59  *			@cputime_atomic receives updates.
60  * @checking_timer:	true when a thread in the group is in the
61  *			process of checking for thread group 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 	bool running;
69 	bool checking_timer;
70 };
71 
72 struct multiprocess_signals {
73 	sigset_t signal;
74 	struct hlist_node node;
75 };
76 
77 /*
78  * NOTE! "signal_struct" does not have its own
79  * locking, because a shared signal_struct always
80  * implies a shared sighand_struct, so locking
81  * sighand_struct is always a proper superset of
82  * the locking of signal_struct.
83  */
84 struct signal_struct {
85 	atomic_t		sigcnt;
86 	atomic_t		live;
87 	int			nr_threads;
88 	struct list_head	thread_head;
89 
90 	wait_queue_head_t	wait_chldexit;	/* for wait4() */
91 
92 	/* current thread group signal load-balancing target: */
93 	struct task_struct	*curr_target;
94 
95 	/* shared signal handling: */
96 	struct sigpending	shared_pending;
97 
98 	/* For collecting multiprocess signals during fork */
99 	struct hlist_head	multiprocess;
100 
101 	/* thread group exit support */
102 	int			group_exit_code;
103 	/* overloaded:
104 	 * - notify group_exit_task when ->count is equal to notify_count
105 	 * - everyone except group_exit_task is stopped during signal delivery
106 	 *   of fatal signals, group_exit_task processes the signal.
107 	 */
108 	int			notify_count;
109 	struct task_struct	*group_exit_task;
110 
111 	/* thread group stop support, overloads group_exit_code too */
112 	int			group_stop_count;
113 	unsigned int		flags; /* see SIGNAL_* flags below */
114 
115 	/*
116 	 * PR_SET_CHILD_SUBREAPER marks a process, like a service
117 	 * manager, to re-parent orphan (double-forking) child processes
118 	 * to this process instead of 'init'. The service manager is
119 	 * able to receive SIGCHLD signals and is able to investigate
120 	 * the process until it calls wait(). All children of this
121 	 * process will inherit a flag if they should look for a
122 	 * child_subreaper process at exit.
123 	 */
124 	unsigned int		is_child_subreaper:1;
125 	unsigned int		has_child_subreaper:1;
126 
127 #ifdef CONFIG_POSIX_TIMERS
128 
129 	/* POSIX.1b Interval Timers */
130 	unsigned int		next_posix_timer_id;
131 	struct list_head	posix_timers;
132 
133 	/* ITIMER_REAL timer for the process */
134 	struct hrtimer real_timer;
135 	ktime_t it_real_incr;
136 
137 	/*
138 	 * ITIMER_PROF and ITIMER_VIRTUAL timers for the process, we use
139 	 * CPUCLOCK_PROF and CPUCLOCK_VIRT for indexing array as these
140 	 * values are defined to 0 and 1 respectively
141 	 */
142 	struct cpu_itimer it[2];
143 
144 	/*
145 	 * Thread group totals for process CPU timers.
146 	 * See thread_group_cputimer(), et al, for details.
147 	 */
148 	struct thread_group_cputimer cputimer;
149 
150 	/* Earliest-expiration cache. */
151 	struct task_cputime cputime_expires;
152 
153 	struct list_head cpu_timers[3];
154 
155 #endif
156 
157 	/* PID/PID hash table linkage. */
158 	struct pid *pids[PIDTYPE_MAX];
159 
160 #ifdef CONFIG_NO_HZ_FULL
161 	atomic_t tick_dep_mask;
162 #endif
163 
164 	struct pid *tty_old_pgrp;
165 
166 	/* boolean value for session group leader */
167 	int leader;
168 
169 	struct tty_struct *tty; /* NULL if no tty */
170 
171 #ifdef CONFIG_SCHED_AUTOGROUP
172 	struct autogroup *autogroup;
173 #endif
174 	/*
175 	 * Cumulative resource counters for dead threads in the group,
176 	 * and for reaped dead child processes forked by this group.
177 	 * Live threads maintain their own counters and add to these
178 	 * in __exit_signal, except for the group leader.
179 	 */
180 	seqlock_t stats_lock;
181 	u64 utime, stime, cutime, cstime;
182 	u64 gtime;
183 	u64 cgtime;
184 	struct prev_cputime prev_cputime;
185 	unsigned long nvcsw, nivcsw, cnvcsw, cnivcsw;
186 	unsigned long min_flt, maj_flt, cmin_flt, cmaj_flt;
187 	unsigned long inblock, oublock, cinblock, coublock;
188 	unsigned long maxrss, cmaxrss;
189 	struct task_io_accounting ioac;
190 
191 	/*
192 	 * Cumulative ns of schedule CPU time fo dead threads in the
193 	 * group, not including a zombie group leader, (This only differs
194 	 * from jiffies_to_ns(utime + stime) if sched_clock uses something
195 	 * other than jiffies.)
196 	 */
197 	unsigned long long sum_sched_runtime;
198 
199 	/*
200 	 * We don't bother to synchronize most readers of this at all,
201 	 * because there is no reader checking a limit that actually needs
202 	 * to get both rlim_cur and rlim_max atomically, and either one
203 	 * alone is a single word that can safely be read normally.
204 	 * getrlimit/setrlimit use task_lock(current->group_leader) to
205 	 * protect this instead of the siglock, because they really
206 	 * have no need to disable irqs.
207 	 */
208 	struct rlimit rlim[RLIM_NLIMITS];
209 
210 #ifdef CONFIG_BSD_PROCESS_ACCT
211 	struct pacct_struct pacct;	/* per-process accounting information */
212 #endif
213 #ifdef CONFIG_TASKSTATS
214 	struct taskstats *stats;
215 #endif
216 #ifdef CONFIG_AUDIT
217 	unsigned audit_tty;
218 	struct tty_audit_buf *tty_audit_buf;
219 #endif
220 
221 	/*
222 	 * Thread is the potential origin of an oom condition; kill first on
223 	 * oom
224 	 */
225 	bool oom_flag_origin;
226 	short oom_score_adj;		/* OOM kill score adjustment */
227 	short oom_score_adj_min;	/* OOM kill score adjustment min value.
228 					 * Only settable by CAP_SYS_RESOURCE. */
229 	struct mm_struct *oom_mm;	/* recorded mm when the thread group got
230 					 * killed by the oom killer */
231 
232 	struct mutex cred_guard_mutex;	/* guard against foreign influences on
233 					 * credential calculations
234 					 * (notably. ptrace) */
235 } __randomize_layout;
236 
237 /*
238  * Bits in flags field of signal_struct.
239  */
240 #define SIGNAL_STOP_STOPPED	0x00000001 /* job control stop in effect */
241 #define SIGNAL_STOP_CONTINUED	0x00000002 /* SIGCONT since WCONTINUED reap */
242 #define SIGNAL_GROUP_EXIT	0x00000004 /* group exit in progress */
243 #define SIGNAL_GROUP_COREDUMP	0x00000008 /* coredump in progress */
244 /*
245  * Pending notifications to parent.
246  */
247 #define SIGNAL_CLD_STOPPED	0x00000010
248 #define SIGNAL_CLD_CONTINUED	0x00000020
249 #define SIGNAL_CLD_MASK		(SIGNAL_CLD_STOPPED|SIGNAL_CLD_CONTINUED)
250 
251 #define SIGNAL_UNKILLABLE	0x00000040 /* for init: ignore fatal signals */
252 
253 #define SIGNAL_STOP_MASK (SIGNAL_CLD_MASK | SIGNAL_STOP_STOPPED | \
254 			  SIGNAL_STOP_CONTINUED)
255 
signal_set_stop_flags(struct signal_struct * sig,unsigned int flags)256 static inline void signal_set_stop_flags(struct signal_struct *sig,
257 					 unsigned int flags)
258 {
259 	WARN_ON(sig->flags & (SIGNAL_GROUP_EXIT|SIGNAL_GROUP_COREDUMP));
260 	sig->flags = (sig->flags & ~SIGNAL_STOP_MASK) | flags;
261 }
262 
263 /* If true, all threads except ->group_exit_task have pending SIGKILL */
signal_group_exit(const struct signal_struct * sig)264 static inline int signal_group_exit(const struct signal_struct *sig)
265 {
266 	return	(sig->flags & SIGNAL_GROUP_EXIT) ||
267 		(sig->group_exit_task != NULL);
268 }
269 
270 extern void flush_signals(struct task_struct *);
271 extern void ignore_signals(struct task_struct *);
272 extern void flush_signal_handlers(struct task_struct *, int force_default);
273 extern int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info);
274 
kernel_dequeue_signal(siginfo_t * info)275 static inline int kernel_dequeue_signal(siginfo_t *info)
276 {
277 	struct task_struct *tsk = current;
278 	siginfo_t __info;
279 	int ret;
280 
281 	spin_lock_irq(&tsk->sighand->siglock);
282 	ret = dequeue_signal(tsk, &tsk->blocked, info ?: &__info);
283 	spin_unlock_irq(&tsk->sighand->siglock);
284 
285 	return ret;
286 }
287 
kernel_signal_stop(void)288 static inline void kernel_signal_stop(void)
289 {
290 	spin_lock_irq(&current->sighand->siglock);
291 	if (current->jobctl & JOBCTL_STOP_DEQUEUED)
292 		set_special_state(TASK_STOPPED);
293 	spin_unlock_irq(&current->sighand->siglock);
294 
295 	schedule();
296 }
297 #ifdef __ARCH_SI_TRAPNO
298 # define ___ARCH_SI_TRAPNO(_a1) , _a1
299 #else
300 # define ___ARCH_SI_TRAPNO(_a1)
301 #endif
302 #ifdef __ia64__
303 # define ___ARCH_SI_IA64(_a1, _a2, _a3) , _a1, _a2, _a3
304 #else
305 # define ___ARCH_SI_IA64(_a1, _a2, _a3)
306 #endif
307 
308 int force_sig_fault(int sig, int code, void __user *addr
309 	___ARCH_SI_TRAPNO(int trapno)
310 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
311 	, struct task_struct *t);
312 int send_sig_fault(int sig, int code, void __user *addr
313 	___ARCH_SI_TRAPNO(int trapno)
314 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
315 	, struct task_struct *t);
316 
317 int force_sig_mceerr(int code, void __user *, short, struct task_struct *);
318 int send_sig_mceerr(int code, void __user *, short, struct task_struct *);
319 
320 int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper);
321 int force_sig_pkuerr(void __user *addr, u32 pkey);
322 
323 int force_sig_ptrace_errno_trap(int errno, void __user *addr);
324 
325 extern int send_sig_info(int, struct siginfo *, struct task_struct *);
326 extern void force_sigsegv(int sig, struct task_struct *p);
327 extern int force_sig_info(int, struct siginfo *, struct task_struct *);
328 extern int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp);
329 extern int kill_pid_info(int sig, struct siginfo *info, struct pid *pid);
330 extern int kill_pid_info_as_cred(int, struct siginfo *, struct pid *,
331 				const struct cred *);
332 extern int kill_pgrp(struct pid *pid, int sig, int priv);
333 extern int kill_pid(struct pid *pid, int sig, int priv);
334 extern __must_check bool do_notify_parent(struct task_struct *, int);
335 extern void __wake_up_parent(struct task_struct *p, struct task_struct *parent);
336 extern void force_sig(int, struct task_struct *);
337 extern int send_sig(int, struct task_struct *, int);
338 extern int zap_other_threads(struct task_struct *p);
339 extern struct sigqueue *sigqueue_alloc(void);
340 extern void sigqueue_free(struct sigqueue *);
341 extern int send_sigqueue(struct sigqueue *, struct pid *, enum pid_type);
342 extern int do_sigaction(int, struct k_sigaction *, struct k_sigaction *);
343 
restart_syscall(void)344 static inline int restart_syscall(void)
345 {
346 	set_tsk_thread_flag(current, TIF_SIGPENDING);
347 	return -ERESTARTNOINTR;
348 }
349 
signal_pending(struct task_struct * p)350 static inline int signal_pending(struct task_struct *p)
351 {
352 	return unlikely(test_tsk_thread_flag(p,TIF_SIGPENDING));
353 }
354 
__fatal_signal_pending(struct task_struct * p)355 static inline int __fatal_signal_pending(struct task_struct *p)
356 {
357 	return unlikely(sigismember(&p->pending.signal, SIGKILL));
358 }
359 
fatal_signal_pending(struct task_struct * p)360 static inline int fatal_signal_pending(struct task_struct *p)
361 {
362 	return signal_pending(p) && __fatal_signal_pending(p);
363 }
364 
signal_pending_state(long state,struct task_struct * p)365 static inline int signal_pending_state(long state, struct task_struct *p)
366 {
367 	if (!(state & (TASK_INTERRUPTIBLE | TASK_WAKEKILL)))
368 		return 0;
369 	if (!signal_pending(p))
370 		return 0;
371 
372 	return (state & TASK_INTERRUPTIBLE) || __fatal_signal_pending(p);
373 }
374 
375 /*
376  * Reevaluate whether the task has signals pending delivery.
377  * Wake the task if so.
378  * This is required every time the blocked sigset_t changes.
379  * callers must hold sighand->siglock.
380  */
381 extern void recalc_sigpending_and_wake(struct task_struct *t);
382 extern void recalc_sigpending(void);
383 extern void calculate_sigpending(void);
384 
385 extern void signal_wake_up_state(struct task_struct *t, unsigned int state);
386 
signal_wake_up(struct task_struct * t,bool resume)387 static inline void signal_wake_up(struct task_struct *t, bool resume)
388 {
389 	signal_wake_up_state(t, resume ? TASK_WAKEKILL : 0);
390 }
ptrace_signal_wake_up(struct task_struct * t,bool resume)391 static inline void ptrace_signal_wake_up(struct task_struct *t, bool resume)
392 {
393 	signal_wake_up_state(t, resume ? __TASK_TRACED : 0);
394 }
395 
396 void task_join_group_stop(struct task_struct *task);
397 
398 #ifdef TIF_RESTORE_SIGMASK
399 /*
400  * Legacy restore_sigmask accessors.  These are inefficient on
401  * SMP architectures because they require atomic operations.
402  */
403 
404 /**
405  * set_restore_sigmask() - make sure saved_sigmask processing gets done
406  *
407  * This sets TIF_RESTORE_SIGMASK and ensures that the arch signal code
408  * will run before returning to user mode, to process the flag.  For
409  * all callers, TIF_SIGPENDING is already set or it's no harm to set
410  * it.  TIF_RESTORE_SIGMASK need not be in the set of bits that the
411  * arch code will notice on return to user mode, in case those bits
412  * are scarce.  We set TIF_SIGPENDING here to ensure that the arch
413  * signal code always gets run when TIF_RESTORE_SIGMASK is set.
414  */
set_restore_sigmask(void)415 static inline void set_restore_sigmask(void)
416 {
417 	set_thread_flag(TIF_RESTORE_SIGMASK);
418 	WARN_ON(!test_thread_flag(TIF_SIGPENDING));
419 }
420 
clear_tsk_restore_sigmask(struct task_struct * tsk)421 static inline void clear_tsk_restore_sigmask(struct task_struct *tsk)
422 {
423 	clear_tsk_thread_flag(tsk, TIF_RESTORE_SIGMASK);
424 }
425 
clear_restore_sigmask(void)426 static inline void clear_restore_sigmask(void)
427 {
428 	clear_thread_flag(TIF_RESTORE_SIGMASK);
429 }
test_tsk_restore_sigmask(struct task_struct * tsk)430 static inline bool test_tsk_restore_sigmask(struct task_struct *tsk)
431 {
432 	return test_tsk_thread_flag(tsk, TIF_RESTORE_SIGMASK);
433 }
test_restore_sigmask(void)434 static inline bool test_restore_sigmask(void)
435 {
436 	return test_thread_flag(TIF_RESTORE_SIGMASK);
437 }
test_and_clear_restore_sigmask(void)438 static inline bool test_and_clear_restore_sigmask(void)
439 {
440 	return test_and_clear_thread_flag(TIF_RESTORE_SIGMASK);
441 }
442 
443 #else	/* TIF_RESTORE_SIGMASK */
444 
445 /* Higher-quality implementation, used if TIF_RESTORE_SIGMASK doesn't exist. */
set_restore_sigmask(void)446 static inline void set_restore_sigmask(void)
447 {
448 	current->restore_sigmask = true;
449 	WARN_ON(!test_thread_flag(TIF_SIGPENDING));
450 }
clear_tsk_restore_sigmask(struct task_struct * tsk)451 static inline void clear_tsk_restore_sigmask(struct task_struct *tsk)
452 {
453 	tsk->restore_sigmask = false;
454 }
clear_restore_sigmask(void)455 static inline void clear_restore_sigmask(void)
456 {
457 	current->restore_sigmask = false;
458 }
test_restore_sigmask(void)459 static inline bool test_restore_sigmask(void)
460 {
461 	return current->restore_sigmask;
462 }
test_tsk_restore_sigmask(struct task_struct * tsk)463 static inline bool test_tsk_restore_sigmask(struct task_struct *tsk)
464 {
465 	return tsk->restore_sigmask;
466 }
test_and_clear_restore_sigmask(void)467 static inline bool test_and_clear_restore_sigmask(void)
468 {
469 	if (!current->restore_sigmask)
470 		return false;
471 	current->restore_sigmask = false;
472 	return true;
473 }
474 #endif
475 
restore_saved_sigmask(void)476 static inline void restore_saved_sigmask(void)
477 {
478 	if (test_and_clear_restore_sigmask())
479 		__set_current_blocked(&current->saved_sigmask);
480 }
481 
sigmask_to_save(void)482 static inline sigset_t *sigmask_to_save(void)
483 {
484 	sigset_t *res = &current->blocked;
485 	if (unlikely(test_restore_sigmask()))
486 		res = &current->saved_sigmask;
487 	return res;
488 }
489 
kill_cad_pid(int sig,int priv)490 static inline int kill_cad_pid(int sig, int priv)
491 {
492 	return kill_pid(cad_pid, sig, priv);
493 }
494 
495 /* These can be the second arg to send_sig_info/send_group_sig_info.  */
496 #define SEND_SIG_NOINFO ((struct siginfo *) 0)
497 #define SEND_SIG_PRIV	((struct siginfo *) 1)
498 #define SEND_SIG_FORCED	((struct siginfo *) 2)
499 
500 /*
501  * True if we are on the alternate signal stack.
502  */
on_sig_stack(unsigned long sp)503 static inline int on_sig_stack(unsigned long sp)
504 {
505 	/*
506 	 * If the signal stack is SS_AUTODISARM then, by construction, we
507 	 * can't be on the signal stack unless user code deliberately set
508 	 * SS_AUTODISARM when we were already on it.
509 	 *
510 	 * This improves reliability: if user state gets corrupted such that
511 	 * the stack pointer points very close to the end of the signal stack,
512 	 * then this check will enable the signal to be handled anyway.
513 	 */
514 	if (current->sas_ss_flags & SS_AUTODISARM)
515 		return 0;
516 
517 #ifdef CONFIG_STACK_GROWSUP
518 	return sp >= current->sas_ss_sp &&
519 		sp - current->sas_ss_sp < current->sas_ss_size;
520 #else
521 	return sp > current->sas_ss_sp &&
522 		sp - current->sas_ss_sp <= current->sas_ss_size;
523 #endif
524 }
525 
sas_ss_flags(unsigned long sp)526 static inline int sas_ss_flags(unsigned long sp)
527 {
528 	if (!current->sas_ss_size)
529 		return SS_DISABLE;
530 
531 	return on_sig_stack(sp) ? SS_ONSTACK : 0;
532 }
533 
sas_ss_reset(struct task_struct * p)534 static inline void sas_ss_reset(struct task_struct *p)
535 {
536 	p->sas_ss_sp = 0;
537 	p->sas_ss_size = 0;
538 	p->sas_ss_flags = SS_DISABLE;
539 }
540 
sigsp(unsigned long sp,struct ksignal * ksig)541 static inline unsigned long sigsp(unsigned long sp, struct ksignal *ksig)
542 {
543 	if (unlikely((ksig->ka.sa.sa_flags & SA_ONSTACK)) && ! sas_ss_flags(sp))
544 #ifdef CONFIG_STACK_GROWSUP
545 		return current->sas_ss_sp;
546 #else
547 		return current->sas_ss_sp + current->sas_ss_size;
548 #endif
549 	return sp;
550 }
551 
552 extern void __cleanup_sighand(struct sighand_struct *);
553 extern void flush_itimer_signals(void);
554 
555 #define tasklist_empty() \
556 	list_empty(&init_task.tasks)
557 
558 #define next_task(p) \
559 	list_entry_rcu((p)->tasks.next, struct task_struct, tasks)
560 
561 #define for_each_process(p) \
562 	for (p = &init_task ; (p = next_task(p)) != &init_task ; )
563 
564 extern bool current_is_single_threaded(void);
565 
566 /*
567  * Careful: do_each_thread/while_each_thread is a double loop so
568  *          'break' will not work as expected - use goto instead.
569  */
570 #define do_each_thread(g, t) \
571 	for (g = t = &init_task ; (g = t = next_task(g)) != &init_task ; ) do
572 
573 #define while_each_thread(g, t) \
574 	while ((t = next_thread(t)) != g)
575 
576 #define __for_each_thread(signal, t)	\
577 	list_for_each_entry_rcu(t, &(signal)->thread_head, thread_node)
578 
579 #define for_each_thread(p, t)		\
580 	__for_each_thread((p)->signal, t)
581 
582 /* Careful: this is a double loop, 'break' won't work as expected. */
583 #define for_each_process_thread(p, t)	\
584 	for_each_process(p) for_each_thread(p, t)
585 
586 typedef int (*proc_visitor)(struct task_struct *p, void *data);
587 void walk_process_tree(struct task_struct *top, proc_visitor, void *);
588 
589 static inline
task_pid_type(struct task_struct * task,enum pid_type type)590 struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
591 {
592 	struct pid *pid;
593 	if (type == PIDTYPE_PID)
594 		pid = task_pid(task);
595 	else
596 		pid = task->signal->pids[type];
597 	return pid;
598 }
599 
task_tgid(struct task_struct * task)600 static inline struct pid *task_tgid(struct task_struct *task)
601 {
602 	return task->signal->pids[PIDTYPE_TGID];
603 }
604 
605 /*
606  * Without tasklist or RCU lock it is not safe to dereference
607  * the result of task_pgrp/task_session even if task == current,
608  * we can race with another thread doing sys_setsid/sys_setpgid.
609  */
task_pgrp(struct task_struct * task)610 static inline struct pid *task_pgrp(struct task_struct *task)
611 {
612 	return task->signal->pids[PIDTYPE_PGID];
613 }
614 
task_session(struct task_struct * task)615 static inline struct pid *task_session(struct task_struct *task)
616 {
617 	return task->signal->pids[PIDTYPE_SID];
618 }
619 
get_nr_threads(struct task_struct * tsk)620 static inline int get_nr_threads(struct task_struct *tsk)
621 {
622 	return tsk->signal->nr_threads;
623 }
624 
thread_group_leader(struct task_struct * p)625 static inline bool thread_group_leader(struct task_struct *p)
626 {
627 	return p->exit_signal >= 0;
628 }
629 
630 /* Do to the insanities of de_thread it is possible for a process
631  * to have the pid of the thread group leader without actually being
632  * the thread group leader.  For iteration through the pids in proc
633  * all we care about is that we have a task with the appropriate
634  * pid, we don't actually care if we have the right task.
635  */
has_group_leader_pid(struct task_struct * p)636 static inline bool has_group_leader_pid(struct task_struct *p)
637 {
638 	return task_pid(p) == task_tgid(p);
639 }
640 
641 static inline
same_thread_group(struct task_struct * p1,struct task_struct * p2)642 bool same_thread_group(struct task_struct *p1, struct task_struct *p2)
643 {
644 	return p1->signal == p2->signal;
645 }
646 
next_thread(const struct task_struct * p)647 static inline struct task_struct *next_thread(const struct task_struct *p)
648 {
649 	return list_entry_rcu(p->thread_group.next,
650 			      struct task_struct, thread_group);
651 }
652 
thread_group_empty(struct task_struct * p)653 static inline int thread_group_empty(struct task_struct *p)
654 {
655 	return list_empty(&p->thread_group);
656 }
657 
658 #define delay_group_leader(p) \
659 		(thread_group_leader(p) && !thread_group_empty(p))
660 
661 extern struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
662 							unsigned long *flags);
663 
lock_task_sighand(struct task_struct * tsk,unsigned long * flags)664 static inline struct sighand_struct *lock_task_sighand(struct task_struct *tsk,
665 						       unsigned long *flags)
666 {
667 	struct sighand_struct *ret;
668 
669 	ret = __lock_task_sighand(tsk, flags);
670 	(void)__cond_lock(&tsk->sighand->siglock, ret);
671 	return ret;
672 }
673 
unlock_task_sighand(struct task_struct * tsk,unsigned long * flags)674 static inline void unlock_task_sighand(struct task_struct *tsk,
675 						unsigned long *flags)
676 {
677 	spin_unlock_irqrestore(&tsk->sighand->siglock, *flags);
678 }
679 
task_rlimit(const struct task_struct * tsk,unsigned int limit)680 static inline unsigned long task_rlimit(const struct task_struct *tsk,
681 		unsigned int limit)
682 {
683 	return READ_ONCE(tsk->signal->rlim[limit].rlim_cur);
684 }
685 
task_rlimit_max(const struct task_struct * tsk,unsigned int limit)686 static inline unsigned long task_rlimit_max(const struct task_struct *tsk,
687 		unsigned int limit)
688 {
689 	return READ_ONCE(tsk->signal->rlim[limit].rlim_max);
690 }
691 
rlimit(unsigned int limit)692 static inline unsigned long rlimit(unsigned int limit)
693 {
694 	return task_rlimit(current, limit);
695 }
696 
rlimit_max(unsigned int limit)697 static inline unsigned long rlimit_max(unsigned int limit)
698 {
699 	return task_rlimit_max(current, limit);
700 }
701 
702 #endif /* _LINUX_SCHED_SIGNAL_H */
703