2 * linux/kernel/signal.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
6 * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
8 * 2003-06-02 Jim Houston - Concurrent Computer Corp.
9 * Changes to use preallocated sigqueue structures
10 * to allow signals to be sent reliably.
13 #include <linux/config.h>
14 #include <linux/slab.h>
15 #include <linux/module.h>
16 #include <linux/smp_lock.h>
17 #include <linux/init.h>
18 #include <linux/sched.h>
20 #include <linux/tty.h>
21 #include <linux/binfmts.h>
22 #include <linux/security.h>
23 #include <linux/ptrace.h>
24 #include <asm/param.h>
25 #include <asm/uaccess.h>
26 #include <asm/unistd.h>
27 #include <asm/siginfo.h>
30 * SLAB caches for signal bits.
33 static kmem_cache_t *sigqueue_cachep;
35 atomic_t nr_queued_signals;
36 int max_queued_signals = 1024;
39 * In POSIX a signal is sent either to a specific thread (Linux task)
40 * or to the process as a whole (Linux thread group). How the signal
41 * is sent determines whether it's to one thread or the whole group,
42 * which determines which signal mask(s) are involved in blocking it
43 * from being delivered until later. When the signal is delivered,
44 * either it's caught or ignored by a user handler or it has a default
45 * effect that applies to the whole thread group (POSIX process).
47 * The possible effects an unblocked signal set to SIG_DFL can have are:
48 * ignore - Nothing Happens
49 * terminate - kill the process, i.e. all threads in the group,
50 * similar to exit_group. The group leader (only) reports
51 * WIFSIGNALED status to its parent.
52 * coredump - write a core dump file describing all threads using
53 * the same mm and then kill all those threads
54 * stop - stop all the threads in the group, i.e. TASK_STOPPED state
56 * SIGKILL and SIGSTOP cannot be caught, blocked, or ignored.
57 * Other signals when not blocked and set to SIG_DFL behaves as follows.
58 * The job control signals also have other special effects.
60 * +--------------------+------------------+
61 * | POSIX signal | default action |
62 * +--------------------+------------------+
63 * | SIGHUP | terminate |
64 * | SIGINT | terminate |
65 * | SIGQUIT | coredump |
66 * | SIGILL | coredump |
67 * | SIGTRAP | coredump |
68 * | SIGABRT/SIGIOT | coredump |
69 * | SIGBUS | coredump |
70 * | SIGFPE | coredump |
71 * | SIGKILL | terminate(+) |
72 * | SIGUSR1 | terminate |
73 * | SIGSEGV | coredump |
74 * | SIGUSR2 | terminate |
75 * | SIGPIPE | terminate |
76 * | SIGALRM | terminate |
77 * | SIGTERM | terminate |
78 * | SIGCHLD | ignore |
79 * | SIGCONT | ignore(*) |
80 * | SIGSTOP | stop(*)(+) |
81 * | SIGTSTP | stop(*) |
82 * | SIGTTIN | stop(*) |
83 * | SIGTTOU | stop(*) |
85 * | SIGXCPU | coredump |
86 * | SIGXFSZ | coredump |
87 * | SIGVTALRM | terminate |
88 * | SIGPROF | terminate |
89 * | SIGPOLL/SIGIO | terminate |
90 * | SIGSYS/SIGUNUSED | coredump |
91 * | SIGSTKFLT | terminate |
92 * | SIGWINCH | ignore |
93 * | SIGPWR | terminate |
94 * | SIGRTMIN-SIGRTMAX | terminate |
95 * +--------------------+------------------+
96 * | non-POSIX signal | default action |
97 * +--------------------+------------------+
98 * | SIGEMT | coredump |
99 * +--------------------+------------------+
101 * (+) For SIGKILL and SIGSTOP the action is "always", not just "default".
102 * (*) Special job control effects:
103 * When SIGCONT is sent, it resumes the process (all threads in the group)
104 * from TASK_STOPPED state and also clears any pending/queued stop signals
105 * (any of those marked with "stop(*)"). This happens regardless of blocking,
106 * catching, or ignoring SIGCONT. When any stop signal is sent, it clears
107 * any pending/queued SIGCONT signals; this happens regardless of blocking,
108 * catching, or ignored the stop signal, though (except for SIGSTOP) the
109 * default action of stopping the process may happen later or never.
113 #define M_SIGEMT M(SIGEMT)
118 #if SIGRTMIN > BITS_PER_LONG
119 #define M(sig) (1ULL << ((sig)-1))
121 #define M(sig) (1UL << ((sig)-1))
123 #define T(sig, mask) (M(sig) & (mask))
125 #define SIG_KERNEL_ONLY_MASK (\
126 M(SIGKILL) | M(SIGSTOP) )
128 #define SIG_KERNEL_STOP_MASK (\
129 M(SIGSTOP) | M(SIGTSTP) | M(SIGTTIN) | M(SIGTTOU) )
131 #define SIG_KERNEL_COREDUMP_MASK (\
132 M(SIGQUIT) | M(SIGILL) | M(SIGTRAP) | M(SIGABRT) | \
133 M(SIGFPE) | M(SIGSEGV) | M(SIGBUS) | M(SIGSYS) | \
134 M(SIGXCPU) | M(SIGXFSZ) | M_SIGEMT )
136 #define SIG_KERNEL_IGNORE_MASK (\
137 M(SIGCONT) | M(SIGCHLD) | M(SIGWINCH) | M(SIGURG) )
139 #define sig_kernel_only(sig) \
140 (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_ONLY_MASK))
141 #define sig_kernel_coredump(sig) \
142 (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_COREDUMP_MASK))
143 #define sig_kernel_ignore(sig) \
144 (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_IGNORE_MASK))
145 #define sig_kernel_stop(sig) \
146 (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_STOP_MASK))
148 #define sig_user_defined(t, signr) \
149 (((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_DFL) && \
150 ((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_IGN))
152 #define sig_fatal(t, signr) \
153 (!T(signr, SIG_KERNEL_IGNORE_MASK|SIG_KERNEL_STOP_MASK) && \
154 (t)->sighand->action[(signr)-1].sa.sa_handler == SIG_DFL)
156 #define sig_avoid_stop_race() \
157 (sigtestsetmask(¤t->pending.signal, M(SIGCONT) | M(SIGKILL)) || \
158 sigtestsetmask(¤t->signal->shared_pending.signal, \
159 M(SIGCONT) | M(SIGKILL)))
161 static int sig_ignored(struct task_struct *t, int sig)
166 * Tracers always want to know about signals..
168 if (t->ptrace & PT_PTRACED)
172 * Blocked signals are never ignored, since the
173 * signal handler may change by the time it is
176 if (sigismember(&t->blocked, sig))
179 /* Is it explicitly or implicitly ignored? */
180 handler = t->sighand->action[sig-1].sa.sa_handler;
181 return handler == SIG_IGN ||
182 (handler == SIG_DFL && sig_kernel_ignore(sig));
186 * Re-calculate pending state from the set of locally pending
187 * signals, globally pending signals, and blocked signals.
189 static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
194 switch (_NSIG_WORDS) {
196 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
197 ready |= signal->sig[i] &~ blocked->sig[i];
200 case 4: ready = signal->sig[3] &~ blocked->sig[3];
201 ready |= signal->sig[2] &~ blocked->sig[2];
202 ready |= signal->sig[1] &~ blocked->sig[1];
203 ready |= signal->sig[0] &~ blocked->sig[0];
206 case 2: ready = signal->sig[1] &~ blocked->sig[1];
207 ready |= signal->sig[0] &~ blocked->sig[0];
210 case 1: ready = signal->sig[0] &~ blocked->sig[0];
215 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
217 fastcall void recalc_sigpending_tsk(struct task_struct *t)
219 if (t->signal->group_stop_count > 0 ||
220 PENDING(&t->pending, &t->blocked) ||
221 PENDING(&t->signal->shared_pending, &t->blocked))
222 set_tsk_thread_flag(t, TIF_SIGPENDING);
224 clear_tsk_thread_flag(t, TIF_SIGPENDING);
227 void recalc_sigpending(void)
229 recalc_sigpending_tsk(current);
232 /* Given the mask, find the first available signal that should be serviced. */
235 next_signal(struct sigpending *pending, sigset_t *mask)
237 unsigned long i, *s, *m, x;
240 s = pending->signal.sig;
242 switch (_NSIG_WORDS) {
244 for (i = 0; i < _NSIG_WORDS; ++i, ++s, ++m)
245 if ((x = *s &~ *m) != 0) {
246 sig = ffz(~x) + i*_NSIG_BPW + 1;
251 case 2: if ((x = s[0] &~ m[0]) != 0)
253 else if ((x = s[1] &~ m[1]) != 0)
260 case 1: if ((x = *s &~ *m) != 0)
268 struct sigqueue *__sigqueue_alloc(void)
270 struct sigqueue *q = 0;
272 if (atomic_read(&nr_queued_signals) < max_queued_signals)
273 q = kmem_cache_alloc(sigqueue_cachep, GFP_ATOMIC);
275 atomic_inc(&nr_queued_signals);
276 INIT_LIST_HEAD(&q->list);
283 static inline void __sigqueue_free(struct sigqueue *q)
285 if (q->flags & SIGQUEUE_PREALLOC)
287 kmem_cache_free(sigqueue_cachep, q);
288 atomic_dec(&nr_queued_signals);
291 static void flush_sigqueue(struct sigpending *queue)
295 sigemptyset(&queue->signal);
296 while (!list_empty(&queue->list)) {
297 q = list_entry(queue->list.next, struct sigqueue , list);
298 list_del_init(&q->list);
304 * Flush all pending signals for a task.
308 flush_signals(struct task_struct *t)
312 spin_lock_irqsave(&t->sighand->siglock, flags);
313 clear_tsk_thread_flag(t,TIF_SIGPENDING);
314 flush_sigqueue(&t->pending);
315 flush_sigqueue(&t->signal->shared_pending);
316 spin_unlock_irqrestore(&t->sighand->siglock, flags);
320 * This function expects the tasklist_lock write-locked.
322 void __exit_sighand(struct task_struct *tsk)
324 struct sighand_struct * sighand = tsk->sighand;
326 /* Ok, we're done with the signal handlers */
328 if (atomic_dec_and_test(&sighand->count))
329 kmem_cache_free(sighand_cachep, sighand);
332 void exit_sighand(struct task_struct *tsk)
334 write_lock_irq(&tasklist_lock);
336 write_unlock_irq(&tasklist_lock);
340 * This function expects the tasklist_lock write-locked.
342 void __exit_signal(struct task_struct *tsk)
344 struct signal_struct * sig = tsk->signal;
345 struct sighand_struct * sighand = tsk->sighand;
349 if (!atomic_read(&sig->count))
351 spin_lock(&sighand->siglock);
352 if (atomic_dec_and_test(&sig->count)) {
353 if (tsk == sig->curr_target)
354 sig->curr_target = next_thread(tsk);
356 spin_unlock(&sighand->siglock);
357 flush_sigqueue(&sig->shared_pending);
360 * If there is any task waiting for the group exit
363 if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count) {
364 wake_up_process(sig->group_exit_task);
365 sig->group_exit_task = NULL;
367 if (tsk == sig->curr_target)
368 sig->curr_target = next_thread(tsk);
370 spin_unlock(&sighand->siglock);
371 sig = NULL; /* Marker for below. */
373 clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
374 flush_sigqueue(&tsk->pending);
377 * We are cleaning up the signal_struct here. We delayed
378 * calling exit_itimers until after flush_sigqueue, just in
379 * case our thread-local pending queue contained a queued
380 * timer signal that would have been cleared in
381 * exit_itimers. When that called sigqueue_free, it would
382 * attempt to re-take the tasklist_lock and deadlock. This
383 * can never happen if we ensure that all queues the
384 * timer's signal might be queued on have been flushed
385 * first. The shared_pending queue, and our own pending
386 * queue are the only queues the timer could be on, since
387 * there are no other threads left in the group and timer
388 * signals are constrained to threads inside the group.
391 kmem_cache_free(signal_cachep, sig);
395 void exit_signal(struct task_struct *tsk)
397 write_lock_irq(&tasklist_lock);
399 write_unlock_irq(&tasklist_lock);
403 * Flush all handlers for a task.
407 flush_signal_handlers(struct task_struct *t, int force_default)
410 struct k_sigaction *ka = &t->sighand->action[0];
411 for (i = _NSIG ; i != 0 ; i--) {
412 if (force_default || ka->sa.sa_handler != SIG_IGN)
413 ka->sa.sa_handler = SIG_DFL;
415 sigemptyset(&ka->sa.sa_mask);
421 /* Notify the system that a driver wants to block all signals for this
422 * process, and wants to be notified if any signals at all were to be
423 * sent/acted upon. If the notifier routine returns non-zero, then the
424 * signal will be acted upon after all. If the notifier routine returns 0,
425 * then then signal will be blocked. Only one block per process is
426 * allowed. priv is a pointer to private data that the notifier routine
427 * can use to determine if the signal should be blocked or not. */
430 block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
434 spin_lock_irqsave(¤t->sighand->siglock, flags);
435 current->notifier_mask = mask;
436 current->notifier_data = priv;
437 current->notifier = notifier;
438 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
441 /* Notify the system that blocking has ended. */
444 unblock_all_signals(void)
448 spin_lock_irqsave(¤t->sighand->siglock, flags);
449 current->notifier = NULL;
450 current->notifier_data = NULL;
452 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
455 static inline int collect_signal(int sig, struct sigpending *list, siginfo_t *info)
457 struct sigqueue *q, *first = 0;
458 int still_pending = 0;
460 if (unlikely(!sigismember(&list->signal, sig)))
464 * Collect the siginfo appropriate to this signal. Check if
465 * there is another siginfo for the same signal.
467 list_for_each_entry(q, &list->list, list) {
468 if (q->info.si_signo == sig) {
477 list_del_init(&first->list);
478 copy_siginfo(info, &first->info);
479 __sigqueue_free(first);
481 sigdelset(&list->signal, sig);
484 /* Ok, it wasn't in the queue. This must be
485 a fast-pathed signal or we must have been
486 out of queue space. So zero out the info.
488 sigdelset(&list->signal, sig);
489 info->si_signo = sig;
498 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
503 sig = next_signal(pending, mask);
505 if (current->notifier) {
506 if (sigismember(current->notifier_mask, sig)) {
507 if (!(current->notifier)(current->notifier_data)) {
508 clear_thread_flag(TIF_SIGPENDING);
514 if (!collect_signal(sig, pending, info))
524 * Dequeue a signal and return the element to the caller, which is
525 * expected to free it.
527 * All callers have to hold the siglock.
529 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
531 int signr = __dequeue_signal(&tsk->pending, mask, info);
533 signr = __dequeue_signal(&tsk->signal->shared_pending,
536 ((info->si_code & __SI_MASK) == __SI_TIMER) &&
537 info->si_sys_private){
538 do_schedule_next_timer(info);
544 * Tell a process that it has a new active signal..
546 * NOTE! we rely on the previous spin_lock to
547 * lock interrupts for us! We can only be called with
548 * "siglock" held, and the local interrupt must
549 * have been disabled when that got acquired!
551 * No need to set need_resched since signal event passing
552 * goes through ->blocked
554 void signal_wake_up(struct task_struct *t, int resume)
558 set_tsk_thread_flag(t, TIF_SIGPENDING);
561 * If resume is set, we want to wake it up in the TASK_STOPPED case.
562 * We don't check for TASK_STOPPED because there is a race with it
563 * executing another processor and just now entering stopped state.
564 * By calling wake_up_process any time resume is set, we ensure
565 * the process will wake up and handle its stop or death signal.
567 mask = TASK_INTERRUPTIBLE;
569 mask |= TASK_STOPPED;
570 if (!wake_up_state(t, mask))
575 * Remove signals in mask from the pending set and queue.
576 * Returns 1 if any signals were found.
578 * All callers must be holding the siglock.
580 static int rm_from_queue(unsigned long mask, struct sigpending *s)
582 struct sigqueue *q, *n;
584 if (!sigtestsetmask(&s->signal, mask))
587 sigdelsetmask(&s->signal, mask);
588 list_for_each_entry_safe(q, n, &s->list, list) {
589 if (q->info.si_signo < SIGRTMIN &&
590 (mask & sigmask(q->info.si_signo))) {
591 list_del_init(&q->list);
599 * Bad permissions for sending the signal
601 static int check_kill_permission(int sig, struct siginfo *info,
602 struct task_struct *t)
605 if (sig < 0 || sig > _NSIG)
608 if ((!info || ((unsigned long)info != 1 &&
609 (unsigned long)info != 2 && SI_FROMUSER(info)))
610 && ((sig != SIGCONT) ||
611 (current->signal->session != t->signal->session))
612 && (current->euid ^ t->suid) && (current->euid ^ t->uid)
613 && (current->uid ^ t->suid) && (current->uid ^ t->uid)
614 && !capable(CAP_KILL))
616 return security_task_kill(t, info, sig);
620 static void do_notify_parent_cldstop(struct task_struct *tsk,
621 struct task_struct *parent);
624 * Handle magic process-wide effects of stop/continue signals.
625 * Unlike the signal actions, these happen immediately at signal-generation
626 * time regardless of blocking, ignoring, or handling. This does the
627 * actual continuing for SIGCONT, but not the actual stopping for stop
628 * signals. The process stop is done as a signal action for SIG_DFL.
630 static void handle_stop_signal(int sig, struct task_struct *p)
632 struct task_struct *t;
634 if (sig_kernel_stop(sig)) {
636 * This is a stop signal. Remove SIGCONT from all queues.
638 rm_from_queue(sigmask(SIGCONT), &p->signal->shared_pending);
641 rm_from_queue(sigmask(SIGCONT), &t->pending);
644 } else if (sig == SIGCONT) {
646 * Remove all stop signals from all queues,
647 * and wake all threads.
649 if (unlikely(p->signal->group_stop_count > 0)) {
651 * There was a group stop in progress. We'll
652 * pretend it finished before we got here. We are
653 * obliged to report it to the parent: if the
654 * SIGSTOP happened "after" this SIGCONT, then it
655 * would have cleared this pending SIGCONT. If it
656 * happened "before" this SIGCONT, then the parent
657 * got the SIGCHLD about the stop finishing before
658 * the continue happened. We do the notification
659 * now, and it's as if the stop had finished and
660 * the SIGCHLD was pending on entry to this kill.
662 p->signal->group_stop_count = 0;
663 if (p->ptrace & PT_PTRACED)
664 do_notify_parent_cldstop(p, p->parent);
666 do_notify_parent_cldstop(
668 p->group_leader->real_parent);
670 rm_from_queue(SIG_KERNEL_STOP_MASK, &p->signal->shared_pending);
674 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
677 * If there is a handler for SIGCONT, we must make
678 * sure that no thread returns to user mode before
679 * we post the signal, in case it was the only
680 * thread eligible to run the signal handler--then
681 * it must not do anything between resuming and
682 * running the handler. With the TIF_SIGPENDING
683 * flag set, the thread will pause and acquire the
684 * siglock that we hold now and until we've queued
685 * the pending signal.
687 * Wake up the stopped thread _after_ setting
690 state = TASK_STOPPED;
691 if (sig_user_defined(t, SIGCONT) && !sigismember(&t->blocked, SIGCONT)) {
692 set_tsk_thread_flag(t, TIF_SIGPENDING);
693 state |= TASK_INTERRUPTIBLE;
695 wake_up_state(t, state);
702 static int send_signal(int sig, struct siginfo *info, struct sigpending *signals)
704 struct sigqueue * q = NULL;
708 * fast-pathed signals for kernel-internal things like SIGSTOP
711 if ((unsigned long)info == 2)
714 /* Real-time signals must be queued if sent by sigqueue, or
715 some other real-time mechanism. It is implementation
716 defined whether kill() does so. We attempt to do so, on
717 the principle of least surprise, but since kill is not
718 allowed to fail with EAGAIN when low on memory we just
719 make sure at least one signal gets delivered and don't
720 pass on the info struct. */
722 if (atomic_read(&nr_queued_signals) < max_queued_signals)
723 q = kmem_cache_alloc(sigqueue_cachep, GFP_ATOMIC);
726 atomic_inc(&nr_queued_signals);
728 list_add_tail(&q->list, &signals->list);
729 switch ((unsigned long) info) {
731 q->info.si_signo = sig;
732 q->info.si_errno = 0;
733 q->info.si_code = SI_USER;
734 q->info.si_pid = current->pid;
735 q->info.si_uid = current->uid;
738 q->info.si_signo = sig;
739 q->info.si_errno = 0;
740 q->info.si_code = SI_KERNEL;
745 copy_siginfo(&q->info, info);
749 if (sig >= SIGRTMIN && info && (unsigned long)info != 1
750 && info->si_code != SI_USER)
752 * Queue overflow, abort. We may abort if the signal was rt
753 * and sent by user using something other than kill().
756 if (((unsigned long)info > 1) && (info->si_code == SI_TIMER))
758 * Set up a return to indicate that we dropped
761 ret = info->si_sys_private;
765 sigaddset(&signals->signal, sig);
769 #define LEGACY_QUEUE(sigptr, sig) \
770 (((sig) < SIGRTMIN) && sigismember(&(sigptr)->signal, (sig)))
774 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
778 if (!irqs_disabled())
781 if (!spin_is_locked(&t->sighand->siglock))
785 if (((unsigned long)info > 2) && (info->si_code == SI_TIMER))
787 * Set up a return to indicate that we dropped the signal.
789 ret = info->si_sys_private;
791 /* Short-circuit ignored signals. */
792 if (sig_ignored(t, sig))
795 /* Support queueing exactly one non-rt signal, so that we
796 can get more detailed information about the cause of
798 if (LEGACY_QUEUE(&t->pending, sig))
801 ret = send_signal(sig, info, &t->pending);
802 if (!ret && !sigismember(&t->blocked, sig))
803 signal_wake_up(t, sig == SIGKILL);
809 * Force a signal that the process can't ignore: if necessary
810 * we unblock the signal and change any SIG_IGN to SIG_DFL.
814 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
816 unsigned long int flags;
819 spin_lock_irqsave(&t->sighand->siglock, flags);
820 if (sigismember(&t->blocked, sig) || t->sighand->action[sig-1].sa.sa_handler == SIG_IGN) {
821 t->sighand->action[sig-1].sa.sa_handler = SIG_DFL;
822 sigdelset(&t->blocked, sig);
823 recalc_sigpending_tsk(t);
825 ret = specific_send_sig_info(sig, info, t);
826 spin_unlock_irqrestore(&t->sighand->siglock, flags);
832 force_sig_specific(int sig, struct task_struct *t)
834 unsigned long int flags;
836 spin_lock_irqsave(&t->sighand->siglock, flags);
837 if (t->sighand->action[sig-1].sa.sa_handler == SIG_IGN)
838 t->sighand->action[sig-1].sa.sa_handler = SIG_DFL;
839 sigdelset(&t->blocked, sig);
840 recalc_sigpending_tsk(t);
841 specific_send_sig_info(sig, (void *)2, t);
842 spin_unlock_irqrestore(&t->sighand->siglock, flags);
846 * Test if P wants to take SIG. After we've checked all threads with this,
847 * it's equivalent to finding no threads not blocking SIG. Any threads not
848 * blocking SIG were ruled out because they are not running and already
849 * have pending signals. Such threads will dequeue from the shared queue
850 * as soon as they're available, so putting the signal on the shared queue
851 * will be equivalent to sending it to one such thread.
853 #define wants_signal(sig, p, mask) \
854 (!sigismember(&(p)->blocked, sig) \
855 && !((p)->state & mask) \
856 && !((p)->flags & PF_EXITING) \
857 && (task_curr(p) || !signal_pending(p)))
861 __group_complete_signal(int sig, struct task_struct *p, unsigned int mask)
863 struct task_struct *t;
866 * Now find a thread we can wake up to take the signal off the queue.
868 * If the main thread wants the signal, it gets first crack.
869 * Probably the least surprising to the average bear.
871 if (wants_signal(sig, p, mask))
873 else if (thread_group_empty(p))
875 * There is just one thread and it does not need to be woken.
876 * It will dequeue unblocked signals before it runs again.
881 * Otherwise try to find a suitable thread.
883 t = p->signal->curr_target;
885 /* restart balancing at this thread */
886 t = p->signal->curr_target = p;
887 BUG_ON(t->tgid != p->tgid);
889 while (!wants_signal(sig, t, mask)) {
891 if (t == p->signal->curr_target)
893 * No thread needs to be woken.
894 * Any eligible threads will see
895 * the signal in the queue soon.
899 p->signal->curr_target = t;
903 * Found a killable thread. If the signal will be fatal,
904 * then start taking the whole group down immediately.
906 if (sig_fatal(p, sig) && !p->signal->group_exit &&
907 !sigismember(&t->real_blocked, sig) &&
908 (sig == SIGKILL || !(t->ptrace & PT_PTRACED))) {
910 * This signal will be fatal to the whole group.
912 if (!sig_kernel_coredump(sig)) {
914 * Start a group exit and wake everybody up.
915 * This way we don't have other threads
916 * running and doing things after a slower
917 * thread has the fatal signal pending.
919 p->signal->group_exit = 1;
920 p->signal->group_exit_code = sig;
921 p->signal->group_stop_count = 0;
924 sigaddset(&t->pending.signal, SIGKILL);
925 signal_wake_up(t, 1);
932 * There will be a core dump. We make all threads other
933 * than the chosen one go into a group stop so that nothing
934 * happens until it gets scheduled, takes the signal off
935 * the shared queue, and does the core dump. This is a
936 * little more complicated than strictly necessary, but it
937 * keeps the signal state that winds up in the core dump
938 * unchanged from the death state, e.g. which thread had
939 * the core-dump signal unblocked.
941 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
942 rm_from_queue(SIG_KERNEL_STOP_MASK, &p->signal->shared_pending);
943 p->signal->group_stop_count = 0;
944 p->signal->group_exit_task = t;
947 p->signal->group_stop_count++;
948 signal_wake_up(t, 0);
951 wake_up_process(p->signal->group_exit_task);
956 * The signal is already in the shared-pending queue.
957 * Tell the chosen thread to wake up and dequeue it.
959 signal_wake_up(t, sig == SIGKILL);
964 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
970 if (!spin_is_locked(&p->sighand->siglock))
973 handle_stop_signal(sig, p);
975 if (((unsigned long)info > 2) && (info->si_code == SI_TIMER))
977 * Set up a return to indicate that we dropped the signal.
979 ret = info->si_sys_private;
981 /* Short-circuit ignored signals. */
982 if (sig_ignored(p, sig))
985 if (LEGACY_QUEUE(&p->signal->shared_pending, sig))
986 /* This is a non-RT signal and we already have one queued. */
990 * Don't bother zombies and stopped tasks (but
991 * SIGKILL will punch through stopped state)
993 mask = TASK_DEAD | TASK_ZOMBIE;
995 mask |= TASK_STOPPED;
998 * Put this signal on the shared-pending queue, or fail with EAGAIN.
999 * We always use the shared queue for process-wide signals,
1000 * to avoid several races.
1002 ret = send_signal(sig, info, &p->signal->shared_pending);
1006 __group_complete_signal(sig, p, mask);
1011 * Nuke all other threads in the group.
1013 void zap_other_threads(struct task_struct *p)
1015 struct task_struct *t;
1017 p->signal->group_stop_count = 0;
1019 if (thread_group_empty(p))
1022 for (t = next_thread(p); t != p; t = next_thread(t)) {
1024 * Don't bother with already dead threads
1026 if (t->state & (TASK_ZOMBIE|TASK_DEAD))
1030 * We don't want to notify the parent, since we are
1031 * killed as part of a thread group due to another
1032 * thread doing an execve() or similar. So set the
1033 * exit signal to -1 to allow immediate reaping of
1034 * the process. But don't detach the thread group
1037 if (t != p->group_leader)
1038 t->exit_signal = -1;
1040 sigaddset(&t->pending.signal, SIGKILL);
1041 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
1042 signal_wake_up(t, 1);
1047 * Must be called with the tasklist_lock held for reading!
1049 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1051 unsigned long flags;
1054 ret = check_kill_permission(sig, info, p);
1055 if (!ret && sig && p->sighand) {
1056 spin_lock_irqsave(&p->sighand->siglock, flags);
1057 ret = __group_send_sig_info(sig, info, p);
1058 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1065 * kill_pg_info() sends a signal to a process group: this is what the tty
1066 * control characters do (^C, ^Z etc)
1069 int __kill_pg_info(int sig, struct siginfo *info, pid_t pgrp)
1071 struct task_struct *p;
1072 struct list_head *l;
1082 for_each_task_pid(pgrp, PIDTYPE_PGID, p, l, pid) {
1086 err = group_send_sig_info(sig, info, p);
1090 return found ? retval : -ESRCH;
1094 kill_pg_info(int sig, struct siginfo *info, pid_t pgrp)
1098 read_lock(&tasklist_lock);
1099 retval = __kill_pg_info(sig, info, pgrp);
1100 read_unlock(&tasklist_lock);
1106 * kill_sl_info() sends a signal to the session leader: this is used
1107 * to send SIGHUP to the controlling process of a terminal when
1108 * the connection is lost.
1113 kill_sl_info(int sig, struct siginfo *info, pid_t sid)
1115 int err, retval = -EINVAL;
1117 struct list_head *l;
1118 struct task_struct *p;
1124 read_lock(&tasklist_lock);
1125 for_each_task_pid(sid, PIDTYPE_SID, p, l, pid) {
1126 if (!p->signal->leader)
1128 err = group_send_sig_info(sig, info, p);
1132 read_unlock(&tasklist_lock);
1138 kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1141 struct task_struct *p;
1143 read_lock(&tasklist_lock);
1144 p = find_task_by_pid(pid);
1147 error = group_send_sig_info(sig, info, p);
1148 read_unlock(&tasklist_lock);
1154 * kill_something_info() interprets pid in interesting ways just like kill(2).
1156 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1157 * is probably wrong. Should make it like BSD or SYSV.
1160 static int kill_something_info(int sig, struct siginfo *info, int pid)
1163 return kill_pg_info(sig, info, process_group(current));
1164 } else if (pid == -1) {
1165 int retval = 0, count = 0;
1166 struct task_struct * p;
1168 read_lock(&tasklist_lock);
1169 for_each_process(p) {
1170 if (p->pid > 1 && p->tgid != current->tgid) {
1171 int err = group_send_sig_info(sig, info, p);
1177 read_unlock(&tasklist_lock);
1178 return count ? retval : -ESRCH;
1179 } else if (pid < 0) {
1180 return kill_pg_info(sig, info, -pid);
1182 return kill_proc_info(sig, info, pid);
1187 * These are for backward compatibility with the rest of the kernel source.
1191 * These two are the most common entry points. They send a signal
1192 * just to the specific thread.
1195 send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1198 unsigned long flags;
1201 * We need the tasklist lock even for the specific
1202 * thread case (when we don't need to follow the group
1203 * lists) in order to avoid races with "p->sighand"
1204 * going away or changing from under us.
1206 read_lock(&tasklist_lock);
1207 spin_lock_irqsave(&p->sighand->siglock, flags);
1208 ret = specific_send_sig_info(sig, info, p);
1209 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1210 read_unlock(&tasklist_lock);
1215 send_sig(int sig, struct task_struct *p, int priv)
1217 return send_sig_info(sig, (void*)(long)(priv != 0), p);
1221 * This is the entry point for "process-wide" signals.
1222 * They will go to an appropriate thread in the thread group.
1225 send_group_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1228 read_lock(&tasklist_lock);
1229 ret = group_send_sig_info(sig, info, p);
1230 read_unlock(&tasklist_lock);
1235 force_sig(int sig, struct task_struct *p)
1237 force_sig_info(sig, (void*)1L, p);
1241 kill_pg(pid_t pgrp, int sig, int priv)
1243 return kill_pg_info(sig, (void *)(long)(priv != 0), pgrp);
1247 kill_sl(pid_t sess, int sig, int priv)
1249 return kill_sl_info(sig, (void *)(long)(priv != 0), sess);
1253 kill_proc(pid_t pid, int sig, int priv)
1255 return kill_proc_info(sig, (void *)(long)(priv != 0), pid);
1259 * These functions support sending signals using preallocated sigqueue
1260 * structures. This is needed "because realtime applications cannot
1261 * afford to lose notifications of asynchronous events, like timer
1262 * expirations or I/O completions". In the case of Posix Timers
1263 * we allocate the sigqueue structure from the timer_create. If this
1264 * allocation fails we are able to report the failure to the application
1265 * with an EAGAIN error.
1268 struct sigqueue *sigqueue_alloc(void)
1272 if ((q = __sigqueue_alloc()))
1273 q->flags |= SIGQUEUE_PREALLOC;
1277 void sigqueue_free(struct sigqueue *q)
1279 unsigned long flags;
1280 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1282 * If the signal is still pending remove it from the
1285 if (unlikely(!list_empty(&q->list))) {
1286 read_lock(&tasklist_lock);
1287 spin_lock_irqsave(q->lock, flags);
1288 if (!list_empty(&q->list))
1289 list_del_init(&q->list);
1290 spin_unlock_irqrestore(q->lock, flags);
1291 read_unlock(&tasklist_lock);
1293 q->flags &= ~SIGQUEUE_PREALLOC;
1298 send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
1300 unsigned long flags;
1304 * We need the tasklist lock even for the specific
1305 * thread case (when we don't need to follow the group
1306 * lists) in order to avoid races with "p->sighand"
1307 * going away or changing from under us.
1309 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1310 read_lock(&tasklist_lock);
1311 spin_lock_irqsave(&p->sighand->siglock, flags);
1313 if (unlikely(!list_empty(&q->list))) {
1315 * If an SI_TIMER entry is already queue just increment
1316 * the overrun count.
1318 if (q->info.si_code != SI_TIMER)
1320 q->info.si_overrun++;
1323 /* Short-circuit ignored signals. */
1324 if (sig_ignored(p, sig)) {
1329 q->lock = &p->sighand->siglock;
1330 list_add_tail(&q->list, &p->pending.list);
1331 sigaddset(&p->pending.signal, sig);
1332 if (!sigismember(&p->blocked, sig))
1333 signal_wake_up(p, sig == SIGKILL);
1336 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1337 read_unlock(&tasklist_lock);
1342 send_group_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
1344 unsigned long flags;
1348 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1349 read_lock(&tasklist_lock);
1350 spin_lock_irqsave(&p->sighand->siglock, flags);
1351 handle_stop_signal(sig, p);
1353 /* Short-circuit ignored signals. */
1354 if (sig_ignored(p, sig)) {
1359 if (unlikely(!list_empty(&q->list))) {
1361 * If an SI_TIMER entry is already queue just increment
1362 * the overrun count. Other uses should not try to
1363 * send the signal multiple times.
1365 if (q->info.si_code != SI_TIMER)
1367 q->info.si_overrun++;
1371 * Don't bother zombies and stopped tasks (but
1372 * SIGKILL will punch through stopped state)
1374 mask = TASK_DEAD | TASK_ZOMBIE;
1376 mask |= TASK_STOPPED;
1379 * Put this signal on the shared-pending queue.
1380 * We always use the shared queue for process-wide signals,
1381 * to avoid several races.
1383 q->lock = &p->sighand->siglock;
1384 list_add_tail(&q->list, &p->signal->shared_pending.list);
1385 sigaddset(&p->signal->shared_pending.signal, sig);
1387 __group_complete_signal(sig, p, mask);
1389 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1390 read_unlock(&tasklist_lock);
1395 * Joy. Or not. Pthread wants us to wake up every thread
1396 * in our parent group.
1398 static void __wake_up_parent(struct task_struct *p,
1399 struct task_struct *parent)
1401 struct task_struct *tsk = parent;
1404 * Fortunately this is not necessary for thread groups:
1406 if (p->tgid == tsk->tgid) {
1407 wake_up_interruptible_sync(&tsk->wait_chldexit);
1412 wake_up_interruptible_sync(&tsk->wait_chldexit);
1413 tsk = next_thread(tsk);
1414 if (tsk->signal != parent->signal)
1416 } while (tsk != parent);
1420 * Let a parent know about a status change of a child.
1423 void do_notify_parent(struct task_struct *tsk, int sig)
1425 struct siginfo info;
1426 unsigned long flags;
1428 struct sighand_struct *psig;
1433 BUG_ON(tsk->group_leader != tsk && tsk->group_leader->state != TASK_ZOMBIE && !tsk->ptrace);
1434 BUG_ON(tsk->group_leader == tsk && !thread_group_empty(tsk) && !tsk->ptrace);
1436 info.si_signo = sig;
1438 info.si_pid = tsk->pid;
1439 info.si_uid = tsk->uid;
1441 /* FIXME: find out whether or not this is supposed to be c*time. */
1442 info.si_utime = tsk->utime;
1443 info.si_stime = tsk->stime;
1445 status = tsk->exit_code & 0x7f;
1446 why = SI_KERNEL; /* shouldn't happen */
1447 switch (tsk->state) {
1449 /* FIXME -- can we deduce CLD_TRAPPED or CLD_CONTINUED? */
1450 if (tsk->ptrace & PT_PTRACED)
1457 if (tsk->exit_code & 0x80)
1459 else if (tsk->exit_code & 0x7f)
1463 status = tsk->exit_code >> 8;
1468 info.si_status = status;
1470 psig = tsk->parent->sighand;
1471 spin_lock_irqsave(&psig->siglock, flags);
1472 if (sig == SIGCHLD && tsk->state != TASK_STOPPED &&
1473 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1474 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1476 * We are exiting and our parent doesn't care. POSIX.1
1477 * defines special semantics for setting SIGCHLD to SIG_IGN
1478 * or setting the SA_NOCLDWAIT flag: we should be reaped
1479 * automatically and not left for our parent's wait4 call.
1480 * Rather than having the parent do it as a magic kind of
1481 * signal handler, we just set this to tell do_exit that we
1482 * can be cleaned up without becoming a zombie. Note that
1483 * we still call __wake_up_parent in this case, because a
1484 * blocked sys_wait4 might now return -ECHILD.
1486 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1487 * is implementation-defined: we do (if you don't want
1488 * it, just use SIG_IGN instead).
1490 tsk->exit_signal = -1;
1491 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1494 if (sig > 0 && sig <= _NSIG)
1495 __group_send_sig_info(sig, &info, tsk->parent);
1496 __wake_up_parent(tsk, tsk->parent);
1497 spin_unlock_irqrestore(&psig->siglock, flags);
1502 * We need the tasklist lock because it's the only
1503 * thing that protects out "parent" pointer.
1505 * exit.c calls "do_notify_parent()" directly, because
1506 * it already has the tasklist lock.
1509 notify_parent(struct task_struct *tsk, int sig)
1512 read_lock(&tasklist_lock);
1513 do_notify_parent(tsk, sig);
1514 read_unlock(&tasklist_lock);
1519 do_notify_parent_cldstop(struct task_struct *tsk, struct task_struct *parent)
1521 struct siginfo info;
1522 unsigned long flags;
1523 struct sighand_struct *sighand;
1525 info.si_signo = SIGCHLD;
1527 info.si_pid = tsk->pid;
1528 info.si_uid = tsk->uid;
1530 /* FIXME: find out whether or not this is supposed to be c*time. */
1531 info.si_utime = tsk->utime;
1532 info.si_stime = tsk->stime;
1534 info.si_status = tsk->exit_code & 0x7f;
1535 info.si_code = CLD_STOPPED;
1537 sighand = parent->sighand;
1538 spin_lock_irqsave(&sighand->siglock, flags);
1539 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1540 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1541 __group_send_sig_info(SIGCHLD, &info, parent);
1543 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1545 __wake_up_parent(tsk, parent);
1546 spin_unlock_irqrestore(&sighand->siglock, flags);
1550 #ifndef HAVE_ARCH_GET_SIGNAL_TO_DELIVER
1553 finish_stop(int stop_count)
1556 * If there are no other threads in the group, or if there is
1557 * a group stop in progress and we are the last to stop,
1558 * report to the parent. When ptraced, every thread reports itself.
1560 if (stop_count < 0 || (current->ptrace & PT_PTRACED)) {
1561 read_lock(&tasklist_lock);
1562 do_notify_parent_cldstop(current, current->parent);
1563 read_unlock(&tasklist_lock);
1565 else if (stop_count == 0) {
1566 read_lock(&tasklist_lock);
1567 do_notify_parent_cldstop(current->group_leader,
1568 current->group_leader->real_parent);
1569 read_unlock(&tasklist_lock);
1574 * Now we don't run again until continued.
1576 current->exit_code = 0;
1580 * This performs the stopping for SIGSTOP and other stop signals.
1581 * We have to stop all threads in the thread group.
1584 do_signal_stop(int signr)
1586 struct signal_struct *sig = current->signal;
1587 struct sighand_struct *sighand = current->sighand;
1588 int stop_count = -1;
1590 /* spin_lock_irq(&sighand->siglock) is now done in caller */
1592 if (sig->group_stop_count > 0) {
1594 * There is a group stop in progress. We don't need to
1595 * start another one.
1597 signr = sig->group_exit_code;
1598 stop_count = --sig->group_stop_count;
1599 current->exit_code = signr;
1600 set_current_state(TASK_STOPPED);
1601 spin_unlock_irq(&sighand->siglock);
1603 else if (thread_group_empty(current)) {
1605 * Lock must be held through transition to stopped state.
1607 current->exit_code = signr;
1608 set_current_state(TASK_STOPPED);
1609 spin_unlock_irq(&sighand->siglock);
1613 * There is no group stop already in progress.
1614 * We must initiate one now, but that requires
1615 * dropping siglock to get both the tasklist lock
1616 * and siglock again in the proper order. Note that
1617 * this allows an intervening SIGCONT to be posted.
1618 * We need to check for that and bail out if necessary.
1620 struct task_struct *t;
1622 spin_unlock_irq(&sighand->siglock);
1624 /* signals can be posted during this window */
1626 read_lock(&tasklist_lock);
1627 spin_lock_irq(&sighand->siglock);
1629 if (unlikely(sig->group_exit)) {
1631 * There is a group exit in progress now.
1632 * We'll just ignore the stop and process the
1633 * associated fatal signal.
1635 spin_unlock_irq(&sighand->siglock);
1636 read_unlock(&tasklist_lock);
1640 if (unlikely(sig_avoid_stop_race())) {
1642 * Either a SIGCONT or a SIGKILL signal was
1643 * posted in the siglock-not-held window.
1645 spin_unlock_irq(&sighand->siglock);
1646 read_unlock(&tasklist_lock);
1650 if (sig->group_stop_count == 0) {
1651 sig->group_exit_code = signr;
1653 for (t = next_thread(current); t != current;
1656 * Setting state to TASK_STOPPED for a group
1657 * stop is always done with the siglock held,
1658 * so this check has no races.
1660 if (t->state < TASK_STOPPED) {
1662 signal_wake_up(t, 0);
1664 sig->group_stop_count = stop_count;
1667 /* A race with another thread while unlocked. */
1668 signr = sig->group_exit_code;
1669 stop_count = --sig->group_stop_count;
1672 current->exit_code = signr;
1673 set_current_state(TASK_STOPPED);
1675 spin_unlock_irq(&sighand->siglock);
1676 read_unlock(&tasklist_lock);
1679 finish_stop(stop_count);
1683 * Do appropriate magic when group_stop_count > 0.
1684 * We return nonzero if we stopped, after releasing the siglock.
1685 * We return zero if we still hold the siglock and should look
1686 * for another signal without checking group_stop_count again.
1688 static inline int handle_group_stop(void)
1692 if (current->signal->group_exit_task == current) {
1694 * Group stop is so we can do a core dump,
1695 * We are the initiating thread, so get on with it.
1697 current->signal->group_exit_task = NULL;
1701 if (current->signal->group_exit)
1703 * Group stop is so another thread can do a core dump,
1704 * or else we are racing against a death signal.
1705 * Just punt the stop so we can get the next signal.
1710 * There is a group stop in progress. We stop
1711 * without any associated signal being in our queue.
1713 stop_count = --current->signal->group_stop_count;
1714 current->exit_code = current->signal->group_exit_code;
1715 set_current_state(TASK_STOPPED);
1716 spin_unlock_irq(¤t->sighand->siglock);
1717 finish_stop(stop_count);
1721 int get_signal_to_deliver(siginfo_t *info, struct pt_regs *regs, void *cookie)
1723 sigset_t *mask = ¤t->blocked;
1727 spin_lock_irq(¤t->sighand->siglock);
1729 struct k_sigaction *ka;
1731 if (unlikely(current->signal->group_stop_count > 0) &&
1732 handle_group_stop())
1735 signr = dequeue_signal(current, mask, info);
1738 break; /* will return 0 */
1740 if ((current->ptrace & PT_PTRACED) && signr != SIGKILL) {
1741 ptrace_signal_deliver(regs, cookie);
1744 * If there is a group stop in progress,
1745 * we must participate in the bookkeeping.
1747 if (current->signal->group_stop_count > 0)
1748 --current->signal->group_stop_count;
1750 /* Let the debugger run. */
1751 current->exit_code = signr;
1752 current->last_siginfo = info;
1753 set_current_state(TASK_STOPPED);
1754 spin_unlock_irq(¤t->sighand->siglock);
1755 notify_parent(current, SIGCHLD);
1758 current->last_siginfo = NULL;
1760 /* We're back. Did the debugger cancel the sig? */
1761 spin_lock_irq(¤t->sighand->siglock);
1762 signr = current->exit_code;
1766 current->exit_code = 0;
1768 /* Update the siginfo structure if the signal has
1769 changed. If the debugger wanted something
1770 specific in the siginfo structure then it should
1771 have updated *info via PTRACE_SETSIGINFO. */
1772 if (signr != info->si_signo) {
1773 info->si_signo = signr;
1775 info->si_code = SI_USER;
1776 info->si_pid = current->parent->pid;
1777 info->si_uid = current->parent->uid;
1780 /* If the (new) signal is now blocked, requeue it. */
1781 if (sigismember(¤t->blocked, signr)) {
1782 specific_send_sig_info(signr, info, current);
1787 ka = ¤t->sighand->action[signr-1];
1788 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
1790 if (ka->sa.sa_handler != SIG_DFL) /* Run the handler. */
1791 break; /* will return non-zero "signr" value */
1794 * Now we are doing the default action for this signal.
1796 if (sig_kernel_ignore(signr)) /* Default is nothing. */
1799 /* Init gets no signals it doesn't want. */
1800 if (current->pid == 1)
1803 if (sig_kernel_stop(signr)) {
1805 * The default action is to stop all threads in
1806 * the thread group. The job control signals
1807 * do nothing in an orphaned pgrp, but SIGSTOP
1808 * always works. Note that siglock needs to be
1809 * dropped during the call to is_orphaned_pgrp()
1810 * because of lock ordering with tasklist_lock.
1811 * This allows an intervening SIGCONT to be posted.
1812 * We need to check for that and bail out if necessary.
1814 if (signr == SIGSTOP) {
1815 do_signal_stop(signr); /* releases siglock */
1818 spin_unlock_irq(¤t->sighand->siglock);
1820 /* signals can be posted during this window */
1822 if (is_orphaned_pgrp(process_group(current)))
1825 spin_lock_irq(¤t->sighand->siglock);
1826 if (unlikely(sig_avoid_stop_race())) {
1828 * Either a SIGCONT or a SIGKILL signal was
1829 * posted in the siglock-not-held window.
1834 do_signal_stop(signr); /* releases siglock */
1838 spin_unlock_irq(¤t->sighand->siglock);
1841 * Anything else is fatal, maybe with a core dump.
1843 current->flags |= PF_SIGNALED;
1844 if (sig_kernel_coredump(signr) &&
1845 do_coredump((long)signr, signr, regs)) {
1847 * That killed all other threads in the group and
1848 * synchronized with their demise, so there can't
1849 * be any more left to kill now. The group_exit
1850 * flags are set by do_coredump. Note that
1851 * thread_group_empty won't always be true yet,
1852 * because those threads were blocked in __exit_mm
1853 * and we just let them go to finish dying.
1855 const int code = signr | 0x80;
1856 BUG_ON(!current->signal->group_exit);
1857 BUG_ON(current->signal->group_exit_code != code);
1863 * Death signals, no core dump.
1865 do_group_exit(signr);
1868 spin_unlock_irq(¤t->sighand->siglock);
1874 EXPORT_SYMBOL(recalc_sigpending);
1875 EXPORT_SYMBOL_GPL(dequeue_signal);
1876 EXPORT_SYMBOL(flush_signals);
1877 EXPORT_SYMBOL(force_sig);
1878 EXPORT_SYMBOL(force_sig_info);
1879 EXPORT_SYMBOL(kill_pg);
1880 EXPORT_SYMBOL(kill_pg_info);
1881 EXPORT_SYMBOL(kill_proc);
1882 EXPORT_SYMBOL(kill_proc_info);
1883 EXPORT_SYMBOL(kill_sl);
1884 EXPORT_SYMBOL(kill_sl_info);
1885 EXPORT_SYMBOL(notify_parent);
1886 EXPORT_SYMBOL(send_sig);
1887 EXPORT_SYMBOL(send_sig_info);
1888 EXPORT_SYMBOL(send_group_sig_info);
1889 EXPORT_SYMBOL(sigqueue_alloc);
1890 EXPORT_SYMBOL(sigqueue_free);
1891 EXPORT_SYMBOL(send_sigqueue);
1892 EXPORT_SYMBOL(send_group_sigqueue);
1893 EXPORT_SYMBOL(sigprocmask);
1894 EXPORT_SYMBOL(block_all_signals);
1895 EXPORT_SYMBOL(unblock_all_signals);
1899 * System call entry points.
1902 asmlinkage long sys_restart_syscall(void)
1904 struct restart_block *restart = ¤t_thread_info()->restart_block;
1905 return restart->fn(restart);
1908 long do_no_restart_syscall(struct restart_block *param)
1914 * We don't need to get the kernel lock - this is all local to this
1915 * particular thread.. (and that's good, because this is _heavily_
1916 * used by various programs)
1920 * This is also useful for kernel threads that want to temporarily
1921 * (or permanently) block certain signals.
1923 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
1924 * interface happily blocks "unblockable" signals like SIGKILL
1927 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
1932 spin_lock_irq(¤t->sighand->siglock);
1933 old_block = current->blocked;
1937 sigorsets(¤t->blocked, ¤t->blocked, set);
1940 signandsets(¤t->blocked, ¤t->blocked, set);
1943 current->blocked = *set;
1948 recalc_sigpending();
1949 spin_unlock_irq(¤t->sighand->siglock);
1951 *oldset = old_block;
1956 sys_rt_sigprocmask(int how, sigset_t __user *set, sigset_t __user *oset, size_t sigsetsize)
1958 int error = -EINVAL;
1959 sigset_t old_set, new_set;
1961 /* XXX: Don't preclude handling different sized sigset_t's. */
1962 if (sigsetsize != sizeof(sigset_t))
1967 if (copy_from_user(&new_set, set, sizeof(*set)))
1969 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
1971 error = sigprocmask(how, &new_set, &old_set);
1977 spin_lock_irq(¤t->sighand->siglock);
1978 old_set = current->blocked;
1979 spin_unlock_irq(¤t->sighand->siglock);
1983 if (copy_to_user(oset, &old_set, sizeof(*oset)))
1991 long do_sigpending(void __user *set, unsigned long sigsetsize)
1993 long error = -EINVAL;
1996 if (sigsetsize > sizeof(sigset_t))
1999 spin_lock_irq(¤t->sighand->siglock);
2000 sigorsets(&pending, ¤t->pending.signal,
2001 ¤t->signal->shared_pending.signal);
2002 spin_unlock_irq(¤t->sighand->siglock);
2004 /* Outside the lock because only this thread touches it. */
2005 sigandsets(&pending, ¤t->blocked, &pending);
2008 if (!copy_to_user(set, &pending, sigsetsize))
2016 sys_rt_sigpending(sigset_t __user *set, size_t sigsetsize)
2018 return do_sigpending(set, sigsetsize);
2021 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2023 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2027 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2029 if (from->si_code < 0)
2030 return __copy_to_user(to, from, sizeof(siginfo_t))
2033 * If you change siginfo_t structure, please be sure
2034 * this code is fixed accordingly.
2035 * It should never copy any pad contained in the structure
2036 * to avoid security leaks, but must copy the generic
2037 * 3 ints plus the relevant union member.
2039 err = __put_user(from->si_signo, &to->si_signo);
2040 err |= __put_user(from->si_errno, &to->si_errno);
2041 err |= __put_user((short)from->si_code, &to->si_code);
2042 switch (from->si_code & __SI_MASK) {
2044 err |= __put_user(from->si_pid, &to->si_pid);
2045 err |= __put_user(from->si_uid, &to->si_uid);
2048 err |= __put_user(from->si_tid, &to->si_tid);
2049 err |= __put_user(from->si_overrun, &to->si_overrun);
2050 err |= __put_user(from->si_ptr, &to->si_ptr);
2053 err |= __put_user(from->si_band, &to->si_band);
2054 err |= __put_user(from->si_fd, &to->si_fd);
2057 err |= __put_user(from->si_addr, &to->si_addr);
2058 #ifdef __ARCH_SI_TRAPNO
2059 err |= __put_user(from->si_trapno, &to->si_trapno);
2063 err |= __put_user(from->si_pid, &to->si_pid);
2064 err |= __put_user(from->si_uid, &to->si_uid);
2065 err |= __put_user(from->si_status, &to->si_status);
2066 err |= __put_user(from->si_utime, &to->si_utime);
2067 err |= __put_user(from->si_stime, &to->si_stime);
2069 case __SI_RT: /* This is not generated by the kernel as of now. */
2070 case __SI_MESGQ: /* But this is */
2071 err |= __put_user(from->si_pid, &to->si_pid);
2072 err |= __put_user(from->si_uid, &to->si_uid);
2073 err |= __put_user(from->si_ptr, &to->si_ptr);
2075 default: /* this is just in case for now ... */
2076 err |= __put_user(from->si_pid, &to->si_pid);
2077 err |= __put_user(from->si_uid, &to->si_uid);
2086 sys_rt_sigtimedwait(const sigset_t __user *uthese,
2087 siginfo_t __user *uinfo,
2088 const struct timespec __user *uts,
2097 /* XXX: Don't preclude handling different sized sigset_t's. */
2098 if (sigsetsize != sizeof(sigset_t))
2101 if (copy_from_user(&these, uthese, sizeof(these)))
2105 * Invert the set of allowed signals to get those we
2108 sigdelsetmask(&these, sigmask(SIGKILL)|sigmask(SIGSTOP));
2112 if (copy_from_user(&ts, uts, sizeof(ts)))
2114 if (ts.tv_nsec >= 1000000000L || ts.tv_nsec < 0
2119 spin_lock_irq(¤t->sighand->siglock);
2120 sig = dequeue_signal(current, &these, &info);
2122 timeout = MAX_SCHEDULE_TIMEOUT;
2124 timeout = (timespec_to_jiffies(&ts)
2125 + (ts.tv_sec || ts.tv_nsec));
2128 /* None ready -- temporarily unblock those we're
2129 * interested while we are sleeping in so that we'll
2130 * be awakened when they arrive. */
2131 current->real_blocked = current->blocked;
2132 sigandsets(¤t->blocked, ¤t->blocked, &these);
2133 recalc_sigpending();
2134 spin_unlock_irq(¤t->sighand->siglock);
2136 current->state = TASK_INTERRUPTIBLE;
2137 timeout = schedule_timeout(timeout);
2139 spin_lock_irq(¤t->sighand->siglock);
2140 sig = dequeue_signal(current, &these, &info);
2141 current->blocked = current->real_blocked;
2142 siginitset(¤t->real_blocked, 0);
2143 recalc_sigpending();
2146 spin_unlock_irq(¤t->sighand->siglock);
2151 if (copy_siginfo_to_user(uinfo, &info))
2164 sys_kill(int pid, int sig)
2166 struct siginfo info;
2168 info.si_signo = sig;
2170 info.si_code = SI_USER;
2171 info.si_pid = current->tgid;
2172 info.si_uid = current->uid;
2174 return kill_something_info(sig, &info, pid);
2178 * sys_tgkill - send signal to one specific thread
2179 * @tgid: the thread group ID of the thread
2180 * @pid: the PID of the thread
2181 * @sig: signal to be sent
2183 * This syscall also checks the tgid and returns -ESRCH even if the PID
2184 * exists but it's not belonging to the target process anymore. This
2185 * method solves the problem of threads exiting and PIDs getting reused.
2187 asmlinkage long sys_tgkill(int tgid, int pid, int sig)
2189 struct siginfo info;
2191 struct task_struct *p;
2193 /* This is only valid for single tasks */
2194 if (pid <= 0 || tgid <= 0)
2197 info.si_signo = sig;
2199 info.si_code = SI_TKILL;
2200 info.si_pid = current->tgid;
2201 info.si_uid = current->uid;
2203 read_lock(&tasklist_lock);
2204 p = find_task_by_pid(pid);
2206 if (p && (p->tgid == tgid)) {
2207 error = check_kill_permission(sig, &info, p);
2209 * The null signal is a permissions and process existence
2210 * probe. No signal is actually delivered.
2212 if (!error && sig && p->sighand) {
2213 spin_lock_irq(&p->sighand->siglock);
2214 handle_stop_signal(sig, p);
2215 error = specific_send_sig_info(sig, &info, p);
2216 spin_unlock_irq(&p->sighand->siglock);
2219 read_unlock(&tasklist_lock);
2224 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2227 sys_tkill(int pid, int sig)
2229 struct siginfo info;
2231 struct task_struct *p;
2233 /* This is only valid for single tasks */
2237 info.si_signo = sig;
2239 info.si_code = SI_TKILL;
2240 info.si_pid = current->tgid;
2241 info.si_uid = current->uid;
2243 read_lock(&tasklist_lock);
2244 p = find_task_by_pid(pid);
2247 error = check_kill_permission(sig, &info, p);
2249 * The null signal is a permissions and process existence
2250 * probe. No signal is actually delivered.
2252 if (!error && sig && p->sighand) {
2253 spin_lock_irq(&p->sighand->siglock);
2254 handle_stop_signal(sig, p);
2255 error = specific_send_sig_info(sig, &info, p);
2256 spin_unlock_irq(&p->sighand->siglock);
2259 read_unlock(&tasklist_lock);
2264 sys_rt_sigqueueinfo(int pid, int sig, siginfo_t __user *uinfo)
2268 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2271 /* Not even root can pretend to send signals from the kernel.
2272 Nor can they impersonate a kill(), which adds source info. */
2273 if (info.si_code >= 0)
2275 info.si_signo = sig;
2277 /* POSIX.1b doesn't mention process groups. */
2278 return kill_proc_info(sig, &info, pid);
2282 do_sigaction(int sig, const struct k_sigaction *act, struct k_sigaction *oact)
2284 struct k_sigaction *k;
2286 if (sig < 1 || sig > _NSIG || (act && sig_kernel_only(sig)))
2289 k = ¤t->sighand->action[sig-1];
2291 spin_lock_irq(¤t->sighand->siglock);
2292 if (signal_pending(current)) {
2294 * If there might be a fatal signal pending on multiple
2295 * threads, make sure we take it before changing the action.
2297 spin_unlock_irq(¤t->sighand->siglock);
2298 return -ERESTARTNOINTR;
2307 * "Setting a signal action to SIG_IGN for a signal that is
2308 * pending shall cause the pending signal to be discarded,
2309 * whether or not it is blocked."
2311 * "Setting a signal action to SIG_DFL for a signal that is
2312 * pending and whose default action is to ignore the signal
2313 * (for example, SIGCHLD), shall cause the pending signal to
2314 * be discarded, whether or not it is blocked"
2316 if (act->sa.sa_handler == SIG_IGN ||
2317 (act->sa.sa_handler == SIG_DFL &&
2318 sig_kernel_ignore(sig))) {
2320 * This is a fairly rare case, so we only take the
2321 * tasklist_lock once we're sure we'll need it.
2322 * Now we must do this little unlock and relock
2323 * dance to maintain the lock hierarchy.
2325 struct task_struct *t = current;
2326 spin_unlock_irq(&t->sighand->siglock);
2327 read_lock(&tasklist_lock);
2328 spin_lock_irq(&t->sighand->siglock);
2330 sigdelsetmask(&k->sa.sa_mask,
2331 sigmask(SIGKILL) | sigmask(SIGSTOP));
2332 rm_from_queue(sigmask(sig), &t->signal->shared_pending);
2334 rm_from_queue(sigmask(sig), &t->pending);
2335 recalc_sigpending_tsk(t);
2337 } while (t != current);
2338 spin_unlock_irq(¤t->sighand->siglock);
2339 read_unlock(&tasklist_lock);
2344 sigdelsetmask(&k->sa.sa_mask,
2345 sigmask(SIGKILL) | sigmask(SIGSTOP));
2348 spin_unlock_irq(¤t->sighand->siglock);
2353 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
2359 oss.ss_sp = (void *) current->sas_ss_sp;
2360 oss.ss_size = current->sas_ss_size;
2361 oss.ss_flags = sas_ss_flags(sp);
2370 if (verify_area(VERIFY_READ, uss, sizeof(*uss))
2371 || __get_user(ss_sp, &uss->ss_sp)
2372 || __get_user(ss_flags, &uss->ss_flags)
2373 || __get_user(ss_size, &uss->ss_size))
2377 if (on_sig_stack(sp))
2383 * Note - this code used to test ss_flags incorrectly
2384 * old code may have been written using ss_flags==0
2385 * to mean ss_flags==SS_ONSTACK (as this was the only
2386 * way that worked) - this fix preserves that older
2389 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
2392 if (ss_flags == SS_DISABLE) {
2397 if (ss_size < MINSIGSTKSZ)
2401 current->sas_ss_sp = (unsigned long) ss_sp;
2402 current->sas_ss_size = ss_size;
2407 if (copy_to_user(uoss, &oss, sizeof(oss)))
2416 #ifdef __ARCH_WANT_SYS_SIGPENDING
2419 sys_sigpending(old_sigset_t __user *set)
2421 return do_sigpending(set, sizeof(*set));
2426 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
2427 /* Some platforms have their own version with special arguments others
2428 support only sys_rt_sigprocmask. */
2431 sys_sigprocmask(int how, old_sigset_t __user *set, old_sigset_t __user *oset)
2434 old_sigset_t old_set, new_set;
2438 if (copy_from_user(&new_set, set, sizeof(*set)))
2440 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
2442 spin_lock_irq(¤t->sighand->siglock);
2443 old_set = current->blocked.sig[0];
2451 sigaddsetmask(¤t->blocked, new_set);
2454 sigdelsetmask(¤t->blocked, new_set);
2457 current->blocked.sig[0] = new_set;
2461 recalc_sigpending();
2462 spin_unlock_irq(¤t->sighand->siglock);
2468 old_set = current->blocked.sig[0];
2471 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2478 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
2480 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
2482 sys_rt_sigaction(int sig,
2483 const struct sigaction __user *act,
2484 struct sigaction __user *oact,
2487 struct k_sigaction new_sa, old_sa;
2490 /* XXX: Don't preclude handling different sized sigset_t's. */
2491 if (sigsetsize != sizeof(sigset_t))
2495 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
2499 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
2502 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
2508 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
2510 #ifdef __ARCH_WANT_SYS_SGETMASK
2513 * For backwards compatibility. Functionality superseded by sigprocmask.
2519 return current->blocked.sig[0];
2523 sys_ssetmask(int newmask)
2527 spin_lock_irq(¤t->sighand->siglock);
2528 old = current->blocked.sig[0];
2530 siginitset(¤t->blocked, newmask & ~(sigmask(SIGKILL)|
2532 recalc_sigpending();
2533 spin_unlock_irq(¤t->sighand->siglock);
2537 #endif /* __ARCH_WANT_SGETMASK */
2539 #ifdef __ARCH_WANT_SYS_SIGNAL
2541 * For backwards compatibility. Functionality superseded by sigaction.
2543 asmlinkage unsigned long
2544 sys_signal(int sig, __sighandler_t handler)
2546 struct k_sigaction new_sa, old_sa;
2549 new_sa.sa.sa_handler = handler;
2550 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
2552 ret = do_sigaction(sig, &new_sa, &old_sa);
2554 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
2556 #endif /* __ARCH_WANT_SYS_SIGNAL */
2558 #ifdef __ARCH_WANT_SYS_PAUSE
2563 current->state = TASK_INTERRUPTIBLE;
2565 return -ERESTARTNOHAND;
2570 void __init signals_init(void)
2573 kmem_cache_create("sigqueue",
2574 sizeof(struct sigqueue),
2575 __alignof__(struct sigqueue),
2576 SLAB_PANIC, NULL, NULL);