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;
36 * In POSIX a signal is sent either to a specific thread (Linux task)
37 * or to the process as a whole (Linux thread group). How the signal
38 * is sent determines whether it's to one thread or the whole group,
39 * which determines which signal mask(s) are involved in blocking it
40 * from being delivered until later. When the signal is delivered,
41 * either it's caught or ignored by a user handler or it has a default
42 * effect that applies to the whole thread group (POSIX process).
44 * The possible effects an unblocked signal set to SIG_DFL can have are:
45 * ignore - Nothing Happens
46 * terminate - kill the process, i.e. all threads in the group,
47 * similar to exit_group. The group leader (only) reports
48 * WIFSIGNALED status to its parent.
49 * coredump - write a core dump file describing all threads using
50 * the same mm and then kill all those threads
51 * stop - stop all the threads in the group, i.e. TASK_STOPPED state
53 * SIGKILL and SIGSTOP cannot be caught, blocked, or ignored.
54 * Other signals when not blocked and set to SIG_DFL behaves as follows.
55 * The job control signals also have other special effects.
57 * +--------------------+------------------+
58 * | POSIX signal | default action |
59 * +--------------------+------------------+
60 * | SIGHUP | terminate |
61 * | SIGINT | terminate |
62 * | SIGQUIT | coredump |
63 * | SIGILL | coredump |
64 * | SIGTRAP | coredump |
65 * | SIGABRT/SIGIOT | coredump |
66 * | SIGBUS | coredump |
67 * | SIGFPE | coredump |
68 * | SIGKILL | terminate(+) |
69 * | SIGUSR1 | terminate |
70 * | SIGSEGV | coredump |
71 * | SIGUSR2 | terminate |
72 * | SIGPIPE | terminate |
73 * | SIGALRM | terminate |
74 * | SIGTERM | terminate |
75 * | SIGCHLD | ignore |
76 * | SIGCONT | ignore(*) |
77 * | SIGSTOP | stop(*)(+) |
78 * | SIGTSTP | stop(*) |
79 * | SIGTTIN | stop(*) |
80 * | SIGTTOU | stop(*) |
82 * | SIGXCPU | coredump |
83 * | SIGXFSZ | coredump |
84 * | SIGVTALRM | terminate |
85 * | SIGPROF | terminate |
86 * | SIGPOLL/SIGIO | terminate |
87 * | SIGSYS/SIGUNUSED | coredump |
88 * | SIGSTKFLT | terminate |
89 * | SIGWINCH | ignore |
90 * | SIGPWR | terminate |
91 * | SIGRTMIN-SIGRTMAX | terminate |
92 * +--------------------+------------------+
93 * | non-POSIX signal | default action |
94 * +--------------------+------------------+
95 * | SIGEMT | coredump |
96 * +--------------------+------------------+
98 * (+) For SIGKILL and SIGSTOP the action is "always", not just "default".
99 * (*) Special job control effects:
100 * When SIGCONT is sent, it resumes the process (all threads in the group)
101 * from TASK_STOPPED state and also clears any pending/queued stop signals
102 * (any of those marked with "stop(*)"). This happens regardless of blocking,
103 * catching, or ignoring SIGCONT. When any stop signal is sent, it clears
104 * any pending/queued SIGCONT signals; this happens regardless of blocking,
105 * catching, or ignored the stop signal, though (except for SIGSTOP) the
106 * default action of stopping the process may happen later or never.
110 #define M_SIGEMT M(SIGEMT)
115 #if SIGRTMIN > BITS_PER_LONG
116 #define M(sig) (1ULL << ((sig)-1))
118 #define M(sig) (1UL << ((sig)-1))
120 #define T(sig, mask) (M(sig) & (mask))
122 #define SIG_KERNEL_ONLY_MASK (\
123 M(SIGKILL) | M(SIGSTOP) )
125 #define SIG_KERNEL_STOP_MASK (\
126 M(SIGSTOP) | M(SIGTSTP) | M(SIGTTIN) | M(SIGTTOU) )
128 #define SIG_KERNEL_COREDUMP_MASK (\
129 M(SIGQUIT) | M(SIGILL) | M(SIGTRAP) | M(SIGABRT) | \
130 M(SIGFPE) | M(SIGSEGV) | M(SIGBUS) | M(SIGSYS) | \
131 M(SIGXCPU) | M(SIGXFSZ) | M_SIGEMT )
133 #define SIG_KERNEL_IGNORE_MASK (\
134 M(SIGCONT) | M(SIGCHLD) | M(SIGWINCH) | M(SIGURG) )
136 #define sig_kernel_only(sig) \
137 (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_ONLY_MASK))
138 #define sig_kernel_coredump(sig) \
139 (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_COREDUMP_MASK))
140 #define sig_kernel_ignore(sig) \
141 (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_IGNORE_MASK))
142 #define sig_kernel_stop(sig) \
143 (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_STOP_MASK))
145 #define sig_user_defined(t, signr) \
146 (((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_DFL) && \
147 ((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_IGN))
149 #define sig_fatal(t, signr) \
150 (!T(signr, SIG_KERNEL_IGNORE_MASK|SIG_KERNEL_STOP_MASK) && \
151 (t)->sighand->action[(signr)-1].sa.sa_handler == SIG_DFL)
153 #define sig_avoid_stop_race() \
154 (sigtestsetmask(¤t->pending.signal, M(SIGCONT) | M(SIGKILL)) || \
155 sigtestsetmask(¤t->signal->shared_pending.signal, \
156 M(SIGCONT) | M(SIGKILL)))
158 static int sig_ignored(struct task_struct *t, int sig)
160 void __user * handler;
163 * Tracers always want to know about signals..
165 if (t->ptrace & PT_PTRACED)
169 * Blocked signals are never ignored, since the
170 * signal handler may change by the time it is
173 if (sigismember(&t->blocked, sig))
176 /* Is it explicitly or implicitly ignored? */
177 handler = t->sighand->action[sig-1].sa.sa_handler;
178 return handler == SIG_IGN ||
179 (handler == SIG_DFL && sig_kernel_ignore(sig));
183 * Re-calculate pending state from the set of locally pending
184 * signals, globally pending signals, and blocked signals.
186 static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
191 switch (_NSIG_WORDS) {
193 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
194 ready |= signal->sig[i] &~ blocked->sig[i];
197 case 4: ready = signal->sig[3] &~ blocked->sig[3];
198 ready |= signal->sig[2] &~ blocked->sig[2];
199 ready |= signal->sig[1] &~ blocked->sig[1];
200 ready |= signal->sig[0] &~ blocked->sig[0];
203 case 2: ready = signal->sig[1] &~ blocked->sig[1];
204 ready |= signal->sig[0] &~ blocked->sig[0];
207 case 1: ready = signal->sig[0] &~ blocked->sig[0];
212 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
214 fastcall void recalc_sigpending_tsk(struct task_struct *t)
216 if (t->signal->group_stop_count > 0 ||
217 PENDING(&t->pending, &t->blocked) ||
218 PENDING(&t->signal->shared_pending, &t->blocked))
219 set_tsk_thread_flag(t, TIF_SIGPENDING);
221 clear_tsk_thread_flag(t, TIF_SIGPENDING);
224 void recalc_sigpending(void)
226 recalc_sigpending_tsk(current);
229 /* Given the mask, find the first available signal that should be serviced. */
232 next_signal(struct sigpending *pending, sigset_t *mask)
234 unsigned long i, *s, *m, x;
237 s = pending->signal.sig;
239 switch (_NSIG_WORDS) {
241 for (i = 0; i < _NSIG_WORDS; ++i, ++s, ++m)
242 if ((x = *s &~ *m) != 0) {
243 sig = ffz(~x) + i*_NSIG_BPW + 1;
248 case 2: if ((x = s[0] &~ m[0]) != 0)
250 else if ((x = s[1] &~ m[1]) != 0)
257 case 1: if ((x = *s &~ *m) != 0)
265 static struct sigqueue *__sigqueue_alloc(void)
267 struct sigqueue *q = NULL;
269 if (atomic_read(¤t->user->sigpending) <
270 current->rlim[RLIMIT_SIGPENDING].rlim_cur)
271 q = kmem_cache_alloc(sigqueue_cachep, GFP_ATOMIC);
273 INIT_LIST_HEAD(&q->list);
276 q->user = get_uid(current->user);
277 atomic_inc(&q->user->sigpending);
282 static inline void __sigqueue_free(struct sigqueue *q)
284 if (q->flags & SIGQUEUE_PREALLOC)
286 atomic_dec(&q->user->sigpending);
288 kmem_cache_free(sigqueue_cachep, q);
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 = NULL;
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 task_struct *t,
703 struct sigpending *signals)
705 struct sigqueue * q = NULL;
709 * fast-pathed signals for kernel-internal things like SIGSTOP
712 if ((unsigned long)info == 2)
715 /* Real-time signals must be queued if sent by sigqueue, or
716 some other real-time mechanism. It is implementation
717 defined whether kill() does so. We attempt to do so, on
718 the principle of least surprise, but since kill is not
719 allowed to fail with EAGAIN when low on memory we just
720 make sure at least one signal gets delivered and don't
721 pass on the info struct. */
723 if (atomic_read(&t->user->sigpending) <
724 t->rlim[RLIMIT_SIGPENDING].rlim_cur)
725 q = kmem_cache_alloc(sigqueue_cachep, GFP_ATOMIC);
729 q->user = get_uid(t->user);
730 atomic_inc(&q->user->sigpending);
731 list_add_tail(&q->list, &signals->list);
732 switch ((unsigned long) info) {
734 q->info.si_signo = sig;
735 q->info.si_errno = 0;
736 q->info.si_code = SI_USER;
737 q->info.si_pid = current->pid;
738 q->info.si_uid = current->uid;
741 q->info.si_signo = sig;
742 q->info.si_errno = 0;
743 q->info.si_code = SI_KERNEL;
748 copy_siginfo(&q->info, info);
752 if (sig >= SIGRTMIN && info && (unsigned long)info != 1
753 && info->si_code != SI_USER)
755 * Queue overflow, abort. We may abort if the signal was rt
756 * and sent by user using something other than kill().
759 if (((unsigned long)info > 1) && (info->si_code == SI_TIMER))
761 * Set up a return to indicate that we dropped
764 ret = info->si_sys_private;
768 sigaddset(&signals->signal, sig);
772 #define LEGACY_QUEUE(sigptr, sig) \
773 (((sig) < SIGRTMIN) && sigismember(&(sigptr)->signal, (sig)))
777 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
781 if (!irqs_disabled())
784 if (!spin_is_locked(&t->sighand->siglock))
788 if (((unsigned long)info > 2) && (info->si_code == SI_TIMER))
790 * Set up a return to indicate that we dropped the signal.
792 ret = info->si_sys_private;
794 /* Short-circuit ignored signals. */
795 if (sig_ignored(t, sig))
798 /* Support queueing exactly one non-rt signal, so that we
799 can get more detailed information about the cause of
801 if (LEGACY_QUEUE(&t->pending, sig))
804 ret = send_signal(sig, info, t, &t->pending);
805 if (!ret && !sigismember(&t->blocked, sig))
806 signal_wake_up(t, sig == SIGKILL);
812 * Force a signal that the process can't ignore: if necessary
813 * we unblock the signal and change any SIG_IGN to SIG_DFL.
817 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
819 unsigned long int flags;
822 spin_lock_irqsave(&t->sighand->siglock, flags);
823 if (sigismember(&t->blocked, sig) || t->sighand->action[sig-1].sa.sa_handler == SIG_IGN) {
824 t->sighand->action[sig-1].sa.sa_handler = SIG_DFL;
825 sigdelset(&t->blocked, sig);
826 recalc_sigpending_tsk(t);
828 ret = specific_send_sig_info(sig, info, t);
829 spin_unlock_irqrestore(&t->sighand->siglock, flags);
835 force_sig_specific(int sig, struct task_struct *t)
837 unsigned long int flags;
839 spin_lock_irqsave(&t->sighand->siglock, flags);
840 if (t->sighand->action[sig-1].sa.sa_handler == SIG_IGN)
841 t->sighand->action[sig-1].sa.sa_handler = SIG_DFL;
842 sigdelset(&t->blocked, sig);
843 recalc_sigpending_tsk(t);
844 specific_send_sig_info(sig, (void *)2, t);
845 spin_unlock_irqrestore(&t->sighand->siglock, flags);
849 * Test if P wants to take SIG. After we've checked all threads with this,
850 * it's equivalent to finding no threads not blocking SIG. Any threads not
851 * blocking SIG were ruled out because they are not running and already
852 * have pending signals. Such threads will dequeue from the shared queue
853 * as soon as they're available, so putting the signal on the shared queue
854 * will be equivalent to sending it to one such thread.
856 #define wants_signal(sig, p, mask) \
857 (!sigismember(&(p)->blocked, sig) \
858 && !((p)->state & mask) \
859 && !((p)->flags & PF_EXITING) \
860 && (task_curr(p) || !signal_pending(p)))
864 __group_complete_signal(int sig, struct task_struct *p, unsigned int mask)
866 struct task_struct *t;
869 * Now find a thread we can wake up to take the signal off the queue.
871 * If the main thread wants the signal, it gets first crack.
872 * Probably the least surprising to the average bear.
874 if (wants_signal(sig, p, mask))
876 else if (thread_group_empty(p))
878 * There is just one thread and it does not need to be woken.
879 * It will dequeue unblocked signals before it runs again.
884 * Otherwise try to find a suitable thread.
886 t = p->signal->curr_target;
888 /* restart balancing at this thread */
889 t = p->signal->curr_target = p;
890 BUG_ON(t->tgid != p->tgid);
892 while (!wants_signal(sig, t, mask)) {
894 if (t == p->signal->curr_target)
896 * No thread needs to be woken.
897 * Any eligible threads will see
898 * the signal in the queue soon.
902 p->signal->curr_target = t;
906 * Found a killable thread. If the signal will be fatal,
907 * then start taking the whole group down immediately.
909 if (sig_fatal(p, sig) && !p->signal->group_exit &&
910 !sigismember(&t->real_blocked, sig) &&
911 (sig == SIGKILL || !(t->ptrace & PT_PTRACED))) {
913 * This signal will be fatal to the whole group.
915 if (!sig_kernel_coredump(sig)) {
917 * Start a group exit and wake everybody up.
918 * This way we don't have other threads
919 * running and doing things after a slower
920 * thread has the fatal signal pending.
922 p->signal->group_exit = 1;
923 p->signal->group_exit_code = sig;
924 p->signal->group_stop_count = 0;
927 sigaddset(&t->pending.signal, SIGKILL);
928 signal_wake_up(t, 1);
935 * There will be a core dump. We make all threads other
936 * than the chosen one go into a group stop so that nothing
937 * happens until it gets scheduled, takes the signal off
938 * the shared queue, and does the core dump. This is a
939 * little more complicated than strictly necessary, but it
940 * keeps the signal state that winds up in the core dump
941 * unchanged from the death state, e.g. which thread had
942 * the core-dump signal unblocked.
944 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
945 rm_from_queue(SIG_KERNEL_STOP_MASK, &p->signal->shared_pending);
946 p->signal->group_stop_count = 0;
947 p->signal->group_exit_task = t;
950 p->signal->group_stop_count++;
951 signal_wake_up(t, 0);
954 wake_up_process(p->signal->group_exit_task);
959 * The signal is already in the shared-pending queue.
960 * Tell the chosen thread to wake up and dequeue it.
962 signal_wake_up(t, sig == SIGKILL);
967 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
973 if (!spin_is_locked(&p->sighand->siglock))
976 handle_stop_signal(sig, p);
978 if (((unsigned long)info > 2) && (info->si_code == SI_TIMER))
980 * Set up a return to indicate that we dropped the signal.
982 ret = info->si_sys_private;
984 /* Short-circuit ignored signals. */
985 if (sig_ignored(p, sig))
988 if (LEGACY_QUEUE(&p->signal->shared_pending, sig))
989 /* This is a non-RT signal and we already have one queued. */
993 * Don't bother zombies and stopped tasks (but
994 * SIGKILL will punch through stopped state)
996 mask = TASK_DEAD | TASK_ZOMBIE;
998 mask |= TASK_STOPPED;
1001 * Put this signal on the shared-pending queue, or fail with EAGAIN.
1002 * We always use the shared queue for process-wide signals,
1003 * to avoid several races.
1005 ret = send_signal(sig, info, p, &p->signal->shared_pending);
1009 __group_complete_signal(sig, p, mask);
1014 * Nuke all other threads in the group.
1016 void zap_other_threads(struct task_struct *p)
1018 struct task_struct *t;
1020 p->signal->group_stop_count = 0;
1022 if (thread_group_empty(p))
1025 for (t = next_thread(p); t != p; t = next_thread(t)) {
1027 * Don't bother with already dead threads
1029 if (t->state & (TASK_ZOMBIE|TASK_DEAD))
1033 * We don't want to notify the parent, since we are
1034 * killed as part of a thread group due to another
1035 * thread doing an execve() or similar. So set the
1036 * exit signal to -1 to allow immediate reaping of
1037 * the process. But don't detach the thread group
1040 if (t != p->group_leader)
1041 t->exit_signal = -1;
1043 sigaddset(&t->pending.signal, SIGKILL);
1044 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
1045 signal_wake_up(t, 1);
1050 * Must be called with the tasklist_lock held for reading!
1052 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1054 unsigned long flags;
1057 ret = check_kill_permission(sig, info, p);
1058 if (!ret && sig && p->sighand) {
1059 spin_lock_irqsave(&p->sighand->siglock, flags);
1060 ret = __group_send_sig_info(sig, info, p);
1061 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1068 * kill_pg_info() sends a signal to a process group: this is what the tty
1069 * control characters do (^C, ^Z etc)
1072 int __kill_pg_info(int sig, struct siginfo *info, pid_t pgrp)
1074 struct task_struct *p;
1075 struct list_head *l;
1077 int retval, success;
1084 for_each_task_pid(pgrp, PIDTYPE_PGID, p, l, pid) {
1085 int err = group_send_sig_info(sig, info, p);
1089 return success ? 0 : retval;
1093 kill_pg_info(int sig, struct siginfo *info, pid_t pgrp)
1097 read_lock(&tasklist_lock);
1098 retval = __kill_pg_info(sig, info, pgrp);
1099 read_unlock(&tasklist_lock);
1105 * kill_sl_info() sends a signal to the session leader: this is used
1106 * to send SIGHUP to the controlling process of a terminal when
1107 * the connection is lost.
1112 kill_sl_info(int sig, struct siginfo *info, pid_t sid)
1114 int err, retval = -EINVAL;
1116 struct list_head *l;
1117 struct task_struct *p;
1123 read_lock(&tasklist_lock);
1124 for_each_task_pid(sid, PIDTYPE_SID, p, l, pid) {
1125 if (!p->signal->leader)
1127 err = group_send_sig_info(sig, info, p);
1131 read_unlock(&tasklist_lock);
1137 kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1140 struct task_struct *p;
1142 read_lock(&tasklist_lock);
1143 p = find_task_by_pid(pid);
1146 error = group_send_sig_info(sig, info, p);
1147 read_unlock(&tasklist_lock);
1153 * kill_something_info() interprets pid in interesting ways just like kill(2).
1155 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1156 * is probably wrong. Should make it like BSD or SYSV.
1159 static int kill_something_info(int sig, struct siginfo *info, int pid)
1162 return kill_pg_info(sig, info, process_group(current));
1163 } else if (pid == -1) {
1164 int retval = 0, count = 0;
1165 struct task_struct * p;
1167 read_lock(&tasklist_lock);
1168 for_each_process(p) {
1169 if (p->pid > 1 && p->tgid != current->tgid) {
1170 int err = group_send_sig_info(sig, info, p);
1176 read_unlock(&tasklist_lock);
1177 return count ? retval : -ESRCH;
1178 } else if (pid < 0) {
1179 return kill_pg_info(sig, info, -pid);
1181 return kill_proc_info(sig, info, pid);
1186 * These are for backward compatibility with the rest of the kernel source.
1190 * These two are the most common entry points. They send a signal
1191 * just to the specific thread.
1194 send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1197 unsigned long flags;
1200 * Make sure legacy kernel users don't send in bad values
1201 * (normal paths check this in check_kill_permission).
1203 if (sig < 0 || sig > _NSIG)
1207 * We need the tasklist lock even for the specific
1208 * thread case (when we don't need to follow the group
1209 * lists) in order to avoid races with "p->sighand"
1210 * going away or changing from under us.
1212 read_lock(&tasklist_lock);
1213 spin_lock_irqsave(&p->sighand->siglock, flags);
1214 ret = specific_send_sig_info(sig, info, p);
1215 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1216 read_unlock(&tasklist_lock);
1221 send_sig(int sig, struct task_struct *p, int priv)
1223 return send_sig_info(sig, (void*)(long)(priv != 0), p);
1227 * This is the entry point for "process-wide" signals.
1228 * They will go to an appropriate thread in the thread group.
1231 send_group_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1234 read_lock(&tasklist_lock);
1235 ret = group_send_sig_info(sig, info, p);
1236 read_unlock(&tasklist_lock);
1241 force_sig(int sig, struct task_struct *p)
1243 force_sig_info(sig, (void*)1L, p);
1247 kill_pg(pid_t pgrp, int sig, int priv)
1249 return kill_pg_info(sig, (void *)(long)(priv != 0), pgrp);
1253 kill_sl(pid_t sess, int sig, int priv)
1255 return kill_sl_info(sig, (void *)(long)(priv != 0), sess);
1259 kill_proc(pid_t pid, int sig, int priv)
1261 return kill_proc_info(sig, (void *)(long)(priv != 0), pid);
1265 * These functions support sending signals using preallocated sigqueue
1266 * structures. This is needed "because realtime applications cannot
1267 * afford to lose notifications of asynchronous events, like timer
1268 * expirations or I/O completions". In the case of Posix Timers
1269 * we allocate the sigqueue structure from the timer_create. If this
1270 * allocation fails we are able to report the failure to the application
1271 * with an EAGAIN error.
1274 struct sigqueue *sigqueue_alloc(void)
1278 if ((q = __sigqueue_alloc()))
1279 q->flags |= SIGQUEUE_PREALLOC;
1283 void sigqueue_free(struct sigqueue *q)
1285 unsigned long flags;
1286 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1288 * If the signal is still pending remove it from the
1291 if (unlikely(!list_empty(&q->list))) {
1292 read_lock(&tasklist_lock);
1293 spin_lock_irqsave(q->lock, flags);
1294 if (!list_empty(&q->list))
1295 list_del_init(&q->list);
1296 spin_unlock_irqrestore(q->lock, flags);
1297 read_unlock(&tasklist_lock);
1299 q->flags &= ~SIGQUEUE_PREALLOC;
1304 send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
1306 unsigned long flags;
1310 * We need the tasklist lock even for the specific
1311 * thread case (when we don't need to follow the group
1312 * lists) in order to avoid races with "p->sighand"
1313 * going away or changing from under us.
1315 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1316 read_lock(&tasklist_lock);
1317 spin_lock_irqsave(&p->sighand->siglock, flags);
1319 if (unlikely(!list_empty(&q->list))) {
1321 * If an SI_TIMER entry is already queue just increment
1322 * the overrun count.
1324 if (q->info.si_code != SI_TIMER)
1326 q->info.si_overrun++;
1329 /* Short-circuit ignored signals. */
1330 if (sig_ignored(p, sig)) {
1335 q->lock = &p->sighand->siglock;
1336 list_add_tail(&q->list, &p->pending.list);
1337 sigaddset(&p->pending.signal, sig);
1338 if (!sigismember(&p->blocked, sig))
1339 signal_wake_up(p, sig == SIGKILL);
1342 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1343 read_unlock(&tasklist_lock);
1348 send_group_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
1350 unsigned long flags;
1354 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1355 read_lock(&tasklist_lock);
1356 spin_lock_irqsave(&p->sighand->siglock, flags);
1357 handle_stop_signal(sig, p);
1359 /* Short-circuit ignored signals. */
1360 if (sig_ignored(p, sig)) {
1365 if (unlikely(!list_empty(&q->list))) {
1367 * If an SI_TIMER entry is already queue just increment
1368 * the overrun count. Other uses should not try to
1369 * send the signal multiple times.
1371 if (q->info.si_code != SI_TIMER)
1373 q->info.si_overrun++;
1377 * Don't bother zombies and stopped tasks (but
1378 * SIGKILL will punch through stopped state)
1380 mask = TASK_DEAD | TASK_ZOMBIE;
1382 mask |= TASK_STOPPED;
1385 * Put this signal on the shared-pending queue.
1386 * We always use the shared queue for process-wide signals,
1387 * to avoid several races.
1389 q->lock = &p->sighand->siglock;
1390 list_add_tail(&q->list, &p->signal->shared_pending.list);
1391 sigaddset(&p->signal->shared_pending.signal, sig);
1393 __group_complete_signal(sig, p, mask);
1395 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1396 read_unlock(&tasklist_lock);
1401 * Joy. Or not. Pthread wants us to wake up every thread
1402 * in our parent group.
1404 static void __wake_up_parent(struct task_struct *p,
1405 struct task_struct *parent)
1407 struct task_struct *tsk = parent;
1410 * Fortunately this is not necessary for thread groups:
1412 if (p->tgid == tsk->tgid) {
1413 wake_up_interruptible_sync(&tsk->wait_chldexit);
1418 wake_up_interruptible_sync(&tsk->wait_chldexit);
1419 tsk = next_thread(tsk);
1420 if (tsk->signal != parent->signal)
1422 } while (tsk != parent);
1426 * Let a parent know about a status change of a child.
1429 void do_notify_parent(struct task_struct *tsk, int sig)
1431 struct siginfo info;
1432 unsigned long flags;
1434 struct sighand_struct *psig;
1439 BUG_ON(tsk->group_leader != tsk && tsk->group_leader->state != TASK_ZOMBIE && !tsk->ptrace);
1440 BUG_ON(tsk->group_leader == tsk && !thread_group_empty(tsk) && !tsk->ptrace);
1442 info.si_signo = sig;
1444 info.si_pid = tsk->pid;
1445 info.si_uid = tsk->uid;
1447 /* FIXME: find out whether or not this is supposed to be c*time. */
1448 info.si_utime = tsk->utime;
1449 info.si_stime = tsk->stime;
1451 status = tsk->exit_code & 0x7f;
1452 why = SI_KERNEL; /* shouldn't happen */
1453 switch (tsk->state) {
1455 /* FIXME -- can we deduce CLD_TRAPPED or CLD_CONTINUED? */
1456 if (tsk->ptrace & PT_PTRACED)
1463 if (tsk->exit_code & 0x80)
1465 else if (tsk->exit_code & 0x7f)
1469 status = tsk->exit_code >> 8;
1474 info.si_status = status;
1476 psig = tsk->parent->sighand;
1477 spin_lock_irqsave(&psig->siglock, flags);
1478 if (sig == SIGCHLD && tsk->state != TASK_STOPPED &&
1479 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1480 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1482 * We are exiting and our parent doesn't care. POSIX.1
1483 * defines special semantics for setting SIGCHLD to SIG_IGN
1484 * or setting the SA_NOCLDWAIT flag: we should be reaped
1485 * automatically and not left for our parent's wait4 call.
1486 * Rather than having the parent do it as a magic kind of
1487 * signal handler, we just set this to tell do_exit that we
1488 * can be cleaned up without becoming a zombie. Note that
1489 * we still call __wake_up_parent in this case, because a
1490 * blocked sys_wait4 might now return -ECHILD.
1492 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1493 * is implementation-defined: we do (if you don't want
1494 * it, just use SIG_IGN instead).
1496 tsk->exit_signal = -1;
1497 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1500 if (sig > 0 && sig <= _NSIG)
1501 __group_send_sig_info(sig, &info, tsk->parent);
1502 __wake_up_parent(tsk, tsk->parent);
1503 spin_unlock_irqrestore(&psig->siglock, flags);
1508 * We need the tasklist lock because it's the only
1509 * thing that protects out "parent" pointer.
1511 * exit.c calls "do_notify_parent()" directly, because
1512 * it already has the tasklist lock.
1515 notify_parent(struct task_struct *tsk, int sig)
1518 read_lock(&tasklist_lock);
1519 do_notify_parent(tsk, sig);
1520 read_unlock(&tasklist_lock);
1525 do_notify_parent_cldstop(struct task_struct *tsk, struct task_struct *parent)
1527 struct siginfo info;
1528 unsigned long flags;
1529 struct sighand_struct *sighand;
1531 info.si_signo = SIGCHLD;
1533 info.si_pid = tsk->pid;
1534 info.si_uid = tsk->uid;
1536 /* FIXME: find out whether or not this is supposed to be c*time. */
1537 info.si_utime = tsk->utime;
1538 info.si_stime = tsk->stime;
1540 info.si_status = tsk->exit_code & 0x7f;
1541 info.si_code = CLD_STOPPED;
1543 sighand = parent->sighand;
1544 spin_lock_irqsave(&sighand->siglock, flags);
1545 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1546 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1547 __group_send_sig_info(SIGCHLD, &info, parent);
1549 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1551 __wake_up_parent(tsk, parent);
1552 spin_unlock_irqrestore(&sighand->siglock, flags);
1556 #ifndef HAVE_ARCH_GET_SIGNAL_TO_DELIVER
1559 finish_stop(int stop_count)
1562 * If there are no other threads in the group, or if there is
1563 * a group stop in progress and we are the last to stop,
1564 * report to the parent. When ptraced, every thread reports itself.
1566 if (stop_count < 0 || (current->ptrace & PT_PTRACED)) {
1567 read_lock(&tasklist_lock);
1568 do_notify_parent_cldstop(current, current->parent);
1569 read_unlock(&tasklist_lock);
1571 else if (stop_count == 0) {
1572 read_lock(&tasklist_lock);
1573 do_notify_parent_cldstop(current->group_leader,
1574 current->group_leader->real_parent);
1575 read_unlock(&tasklist_lock);
1580 * Now we don't run again until continued.
1582 current->exit_code = 0;
1586 * This performs the stopping for SIGSTOP and other stop signals.
1587 * We have to stop all threads in the thread group.
1590 do_signal_stop(int signr)
1592 struct signal_struct *sig = current->signal;
1593 struct sighand_struct *sighand = current->sighand;
1594 int stop_count = -1;
1596 /* spin_lock_irq(&sighand->siglock) is now done in caller */
1598 if (sig->group_stop_count > 0) {
1600 * There is a group stop in progress. We don't need to
1601 * start another one.
1603 signr = sig->group_exit_code;
1604 stop_count = --sig->group_stop_count;
1605 current->exit_code = signr;
1606 set_current_state(TASK_STOPPED);
1607 spin_unlock_irq(&sighand->siglock);
1609 else if (thread_group_empty(current)) {
1611 * Lock must be held through transition to stopped state.
1613 current->exit_code = signr;
1614 set_current_state(TASK_STOPPED);
1615 spin_unlock_irq(&sighand->siglock);
1619 * There is no group stop already in progress.
1620 * We must initiate one now, but that requires
1621 * dropping siglock to get both the tasklist lock
1622 * and siglock again in the proper order. Note that
1623 * this allows an intervening SIGCONT to be posted.
1624 * We need to check for that and bail out if necessary.
1626 struct task_struct *t;
1628 spin_unlock_irq(&sighand->siglock);
1630 /* signals can be posted during this window */
1632 read_lock(&tasklist_lock);
1633 spin_lock_irq(&sighand->siglock);
1635 if (unlikely(sig->group_exit)) {
1637 * There is a group exit in progress now.
1638 * We'll just ignore the stop and process the
1639 * associated fatal signal.
1641 spin_unlock_irq(&sighand->siglock);
1642 read_unlock(&tasklist_lock);
1646 if (unlikely(sig_avoid_stop_race())) {
1648 * Either a SIGCONT or a SIGKILL signal was
1649 * posted in the siglock-not-held window.
1651 spin_unlock_irq(&sighand->siglock);
1652 read_unlock(&tasklist_lock);
1656 if (sig->group_stop_count == 0) {
1657 sig->group_exit_code = signr;
1659 for (t = next_thread(current); t != current;
1662 * Setting state to TASK_STOPPED for a group
1663 * stop is always done with the siglock held,
1664 * so this check has no races.
1666 if (t->state < TASK_STOPPED) {
1668 signal_wake_up(t, 0);
1670 sig->group_stop_count = stop_count;
1673 /* A race with another thread while unlocked. */
1674 signr = sig->group_exit_code;
1675 stop_count = --sig->group_stop_count;
1678 current->exit_code = signr;
1679 set_current_state(TASK_STOPPED);
1681 spin_unlock_irq(&sighand->siglock);
1682 read_unlock(&tasklist_lock);
1685 finish_stop(stop_count);
1689 * Do appropriate magic when group_stop_count > 0.
1690 * We return nonzero if we stopped, after releasing the siglock.
1691 * We return zero if we still hold the siglock and should look
1692 * for another signal without checking group_stop_count again.
1694 static inline int handle_group_stop(void)
1698 if (current->signal->group_exit_task == current) {
1700 * Group stop is so we can do a core dump,
1701 * We are the initiating thread, so get on with it.
1703 current->signal->group_exit_task = NULL;
1707 if (current->signal->group_exit)
1709 * Group stop is so another thread can do a core dump,
1710 * or else we are racing against a death signal.
1711 * Just punt the stop so we can get the next signal.
1716 * There is a group stop in progress. We stop
1717 * without any associated signal being in our queue.
1719 stop_count = --current->signal->group_stop_count;
1720 current->exit_code = current->signal->group_exit_code;
1721 set_current_state(TASK_STOPPED);
1722 spin_unlock_irq(¤t->sighand->siglock);
1723 finish_stop(stop_count);
1727 int get_signal_to_deliver(siginfo_t *info, struct pt_regs *regs, void *cookie)
1729 sigset_t *mask = ¤t->blocked;
1733 spin_lock_irq(¤t->sighand->siglock);
1735 struct k_sigaction *ka;
1737 if (unlikely(current->signal->group_stop_count > 0) &&
1738 handle_group_stop())
1741 signr = dequeue_signal(current, mask, info);
1744 break; /* will return 0 */
1746 if ((current->ptrace & PT_PTRACED) && signr != SIGKILL) {
1747 ptrace_signal_deliver(regs, cookie);
1750 * If there is a group stop in progress,
1751 * we must participate in the bookkeeping.
1753 if (current->signal->group_stop_count > 0)
1754 --current->signal->group_stop_count;
1756 /* Let the debugger run. */
1757 current->exit_code = signr;
1758 current->last_siginfo = info;
1759 set_current_state(TASK_STOPPED);
1760 spin_unlock_irq(¤t->sighand->siglock);
1761 notify_parent(current, SIGCHLD);
1764 current->last_siginfo = NULL;
1766 /* We're back. Did the debugger cancel the sig? */
1767 spin_lock_irq(¤t->sighand->siglock);
1768 signr = current->exit_code;
1772 current->exit_code = 0;
1774 /* Update the siginfo structure if the signal has
1775 changed. If the debugger wanted something
1776 specific in the siginfo structure then it should
1777 have updated *info via PTRACE_SETSIGINFO. */
1778 if (signr != info->si_signo) {
1779 info->si_signo = signr;
1781 info->si_code = SI_USER;
1782 info->si_pid = current->parent->pid;
1783 info->si_uid = current->parent->uid;
1786 /* If the (new) signal is now blocked, requeue it. */
1787 if (sigismember(¤t->blocked, signr)) {
1788 specific_send_sig_info(signr, info, current);
1793 ka = ¤t->sighand->action[signr-1];
1794 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
1796 if (ka->sa.sa_handler != SIG_DFL) /* Run the handler. */
1797 break; /* will return non-zero "signr" value */
1800 * Now we are doing the default action for this signal.
1802 if (sig_kernel_ignore(signr)) /* Default is nothing. */
1805 /* Init gets no signals it doesn't want. */
1806 if (current->pid == 1)
1809 if (sig_kernel_stop(signr)) {
1811 * The default action is to stop all threads in
1812 * the thread group. The job control signals
1813 * do nothing in an orphaned pgrp, but SIGSTOP
1814 * always works. Note that siglock needs to be
1815 * dropped during the call to is_orphaned_pgrp()
1816 * because of lock ordering with tasklist_lock.
1817 * This allows an intervening SIGCONT to be posted.
1818 * We need to check for that and bail out if necessary.
1820 if (signr == SIGSTOP) {
1821 do_signal_stop(signr); /* releases siglock */
1824 spin_unlock_irq(¤t->sighand->siglock);
1826 /* signals can be posted during this window */
1828 if (is_orphaned_pgrp(process_group(current)))
1831 spin_lock_irq(¤t->sighand->siglock);
1832 if (unlikely(sig_avoid_stop_race())) {
1834 * Either a SIGCONT or a SIGKILL signal was
1835 * posted in the siglock-not-held window.
1840 do_signal_stop(signr); /* releases siglock */
1844 spin_unlock_irq(¤t->sighand->siglock);
1847 * Anything else is fatal, maybe with a core dump.
1849 current->flags |= PF_SIGNALED;
1850 if (sig_kernel_coredump(signr) &&
1851 do_coredump((long)signr, signr, regs)) {
1853 * That killed all other threads in the group and
1854 * synchronized with their demise, so there can't
1855 * be any more left to kill now. The group_exit
1856 * flags are set by do_coredump. Note that
1857 * thread_group_empty won't always be true yet,
1858 * because those threads were blocked in __exit_mm
1859 * and we just let them go to finish dying.
1861 const int code = signr | 0x80;
1862 BUG_ON(!current->signal->group_exit);
1863 BUG_ON(current->signal->group_exit_code != code);
1869 * Death signals, no core dump.
1871 do_group_exit(signr);
1874 spin_unlock_irq(¤t->sighand->siglock);
1880 EXPORT_SYMBOL(recalc_sigpending);
1881 EXPORT_SYMBOL_GPL(dequeue_signal);
1882 EXPORT_SYMBOL(flush_signals);
1883 EXPORT_SYMBOL(force_sig);
1884 EXPORT_SYMBOL(force_sig_info);
1885 EXPORT_SYMBOL(kill_pg);
1886 EXPORT_SYMBOL(kill_pg_info);
1887 EXPORT_SYMBOL(kill_proc);
1888 EXPORT_SYMBOL(kill_proc_info);
1889 EXPORT_SYMBOL(kill_sl);
1890 EXPORT_SYMBOL(kill_sl_info);
1891 EXPORT_SYMBOL(notify_parent);
1892 EXPORT_SYMBOL(send_sig);
1893 EXPORT_SYMBOL(send_sig_info);
1894 EXPORT_SYMBOL(send_group_sig_info);
1895 EXPORT_SYMBOL(sigqueue_alloc);
1896 EXPORT_SYMBOL(sigqueue_free);
1897 EXPORT_SYMBOL(send_sigqueue);
1898 EXPORT_SYMBOL(send_group_sigqueue);
1899 EXPORT_SYMBOL(sigprocmask);
1900 EXPORT_SYMBOL(block_all_signals);
1901 EXPORT_SYMBOL(unblock_all_signals);
1905 * System call entry points.
1908 asmlinkage long sys_restart_syscall(void)
1910 struct restart_block *restart = ¤t_thread_info()->restart_block;
1911 return restart->fn(restart);
1914 long do_no_restart_syscall(struct restart_block *param)
1920 * We don't need to get the kernel lock - this is all local to this
1921 * particular thread.. (and that's good, because this is _heavily_
1922 * used by various programs)
1926 * This is also useful for kernel threads that want to temporarily
1927 * (or permanently) block certain signals.
1929 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
1930 * interface happily blocks "unblockable" signals like SIGKILL
1933 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
1938 spin_lock_irq(¤t->sighand->siglock);
1939 old_block = current->blocked;
1943 sigorsets(¤t->blocked, ¤t->blocked, set);
1946 signandsets(¤t->blocked, ¤t->blocked, set);
1949 current->blocked = *set;
1954 recalc_sigpending();
1955 spin_unlock_irq(¤t->sighand->siglock);
1957 *oldset = old_block;
1962 sys_rt_sigprocmask(int how, sigset_t __user *set, sigset_t __user *oset, size_t sigsetsize)
1964 int error = -EINVAL;
1965 sigset_t old_set, new_set;
1967 /* XXX: Don't preclude handling different sized sigset_t's. */
1968 if (sigsetsize != sizeof(sigset_t))
1973 if (copy_from_user(&new_set, set, sizeof(*set)))
1975 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
1977 error = sigprocmask(how, &new_set, &old_set);
1983 spin_lock_irq(¤t->sighand->siglock);
1984 old_set = current->blocked;
1985 spin_unlock_irq(¤t->sighand->siglock);
1989 if (copy_to_user(oset, &old_set, sizeof(*oset)))
1997 long do_sigpending(void __user *set, unsigned long sigsetsize)
1999 long error = -EINVAL;
2002 if (sigsetsize > sizeof(sigset_t))
2005 spin_lock_irq(¤t->sighand->siglock);
2006 sigorsets(&pending, ¤t->pending.signal,
2007 ¤t->signal->shared_pending.signal);
2008 spin_unlock_irq(¤t->sighand->siglock);
2010 /* Outside the lock because only this thread touches it. */
2011 sigandsets(&pending, ¤t->blocked, &pending);
2014 if (!copy_to_user(set, &pending, sigsetsize))
2022 sys_rt_sigpending(sigset_t __user *set, size_t sigsetsize)
2024 return do_sigpending(set, sigsetsize);
2027 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2029 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2033 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2035 if (from->si_code < 0)
2036 return __copy_to_user(to, from, sizeof(siginfo_t))
2039 * If you change siginfo_t structure, please be sure
2040 * this code is fixed accordingly.
2041 * It should never copy any pad contained in the structure
2042 * to avoid security leaks, but must copy the generic
2043 * 3 ints plus the relevant union member.
2045 err = __put_user(from->si_signo, &to->si_signo);
2046 err |= __put_user(from->si_errno, &to->si_errno);
2047 err |= __put_user((short)from->si_code, &to->si_code);
2048 switch (from->si_code & __SI_MASK) {
2050 err |= __put_user(from->si_pid, &to->si_pid);
2051 err |= __put_user(from->si_uid, &to->si_uid);
2054 err |= __put_user(from->si_tid, &to->si_tid);
2055 err |= __put_user(from->si_overrun, &to->si_overrun);
2056 err |= __put_user(from->si_ptr, &to->si_ptr);
2059 err |= __put_user(from->si_band, &to->si_band);
2060 err |= __put_user(from->si_fd, &to->si_fd);
2063 err |= __put_user(from->si_addr, &to->si_addr);
2064 #ifdef __ARCH_SI_TRAPNO
2065 err |= __put_user(from->si_trapno, &to->si_trapno);
2069 err |= __put_user(from->si_pid, &to->si_pid);
2070 err |= __put_user(from->si_uid, &to->si_uid);
2071 err |= __put_user(from->si_status, &to->si_status);
2072 err |= __put_user(from->si_utime, &to->si_utime);
2073 err |= __put_user(from->si_stime, &to->si_stime);
2075 case __SI_RT: /* This is not generated by the kernel as of now. */
2076 case __SI_MESGQ: /* But this is */
2077 err |= __put_user(from->si_pid, &to->si_pid);
2078 err |= __put_user(from->si_uid, &to->si_uid);
2079 err |= __put_user(from->si_ptr, &to->si_ptr);
2081 default: /* this is just in case for now ... */
2082 err |= __put_user(from->si_pid, &to->si_pid);
2083 err |= __put_user(from->si_uid, &to->si_uid);
2092 sys_rt_sigtimedwait(const sigset_t __user *uthese,
2093 siginfo_t __user *uinfo,
2094 const struct timespec __user *uts,
2103 /* XXX: Don't preclude handling different sized sigset_t's. */
2104 if (sigsetsize != sizeof(sigset_t))
2107 if (copy_from_user(&these, uthese, sizeof(these)))
2111 * Invert the set of allowed signals to get those we
2114 sigdelsetmask(&these, sigmask(SIGKILL)|sigmask(SIGSTOP));
2118 if (copy_from_user(&ts, uts, sizeof(ts)))
2120 if (ts.tv_nsec >= 1000000000L || ts.tv_nsec < 0
2125 spin_lock_irq(¤t->sighand->siglock);
2126 sig = dequeue_signal(current, &these, &info);
2128 timeout = MAX_SCHEDULE_TIMEOUT;
2130 timeout = (timespec_to_jiffies(&ts)
2131 + (ts.tv_sec || ts.tv_nsec));
2134 /* None ready -- temporarily unblock those we're
2135 * interested while we are sleeping in so that we'll
2136 * be awakened when they arrive. */
2137 current->real_blocked = current->blocked;
2138 sigandsets(¤t->blocked, ¤t->blocked, &these);
2139 recalc_sigpending();
2140 spin_unlock_irq(¤t->sighand->siglock);
2142 current->state = TASK_INTERRUPTIBLE;
2143 timeout = schedule_timeout(timeout);
2145 spin_lock_irq(¤t->sighand->siglock);
2146 sig = dequeue_signal(current, &these, &info);
2147 current->blocked = current->real_blocked;
2148 siginitset(¤t->real_blocked, 0);
2149 recalc_sigpending();
2152 spin_unlock_irq(¤t->sighand->siglock);
2157 if (copy_siginfo_to_user(uinfo, &info))
2170 sys_kill(int pid, int sig)
2172 struct siginfo info;
2174 info.si_signo = sig;
2176 info.si_code = SI_USER;
2177 info.si_pid = current->tgid;
2178 info.si_uid = current->uid;
2180 return kill_something_info(sig, &info, pid);
2184 * sys_tgkill - send signal to one specific thread
2185 * @tgid: the thread group ID of the thread
2186 * @pid: the PID of the thread
2187 * @sig: signal to be sent
2189 * This syscall also checks the tgid and returns -ESRCH even if the PID
2190 * exists but it's not belonging to the target process anymore. This
2191 * method solves the problem of threads exiting and PIDs getting reused.
2193 asmlinkage long sys_tgkill(int tgid, int pid, int sig)
2195 struct siginfo info;
2197 struct task_struct *p;
2199 /* This is only valid for single tasks */
2200 if (pid <= 0 || tgid <= 0)
2203 info.si_signo = sig;
2205 info.si_code = SI_TKILL;
2206 info.si_pid = current->tgid;
2207 info.si_uid = current->uid;
2209 read_lock(&tasklist_lock);
2210 p = find_task_by_pid(pid);
2212 if (p && (p->tgid == tgid)) {
2213 error = check_kill_permission(sig, &info, p);
2215 * The null signal is a permissions and process existence
2216 * probe. No signal is actually delivered.
2218 if (!error && sig && p->sighand) {
2219 spin_lock_irq(&p->sighand->siglock);
2220 handle_stop_signal(sig, p);
2221 error = specific_send_sig_info(sig, &info, p);
2222 spin_unlock_irq(&p->sighand->siglock);
2225 read_unlock(&tasklist_lock);
2230 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2233 sys_tkill(int pid, int sig)
2235 struct siginfo info;
2237 struct task_struct *p;
2239 /* This is only valid for single tasks */
2243 info.si_signo = sig;
2245 info.si_code = SI_TKILL;
2246 info.si_pid = current->tgid;
2247 info.si_uid = current->uid;
2249 read_lock(&tasklist_lock);
2250 p = find_task_by_pid(pid);
2253 error = check_kill_permission(sig, &info, p);
2255 * The null signal is a permissions and process existence
2256 * probe. No signal is actually delivered.
2258 if (!error && sig && p->sighand) {
2259 spin_lock_irq(&p->sighand->siglock);
2260 handle_stop_signal(sig, p);
2261 error = specific_send_sig_info(sig, &info, p);
2262 spin_unlock_irq(&p->sighand->siglock);
2265 read_unlock(&tasklist_lock);
2270 sys_rt_sigqueueinfo(int pid, int sig, siginfo_t __user *uinfo)
2274 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2277 /* Not even root can pretend to send signals from the kernel.
2278 Nor can they impersonate a kill(), which adds source info. */
2279 if (info.si_code >= 0)
2281 info.si_signo = sig;
2283 /* POSIX.1b doesn't mention process groups. */
2284 return kill_proc_info(sig, &info, pid);
2288 do_sigaction(int sig, const struct k_sigaction *act, struct k_sigaction *oact)
2290 struct k_sigaction *k;
2292 if (sig < 1 || sig > _NSIG || (act && sig_kernel_only(sig)))
2295 k = ¤t->sighand->action[sig-1];
2297 spin_lock_irq(¤t->sighand->siglock);
2298 if (signal_pending(current)) {
2300 * If there might be a fatal signal pending on multiple
2301 * threads, make sure we take it before changing the action.
2303 spin_unlock_irq(¤t->sighand->siglock);
2304 return -ERESTARTNOINTR;
2313 * "Setting a signal action to SIG_IGN for a signal that is
2314 * pending shall cause the pending signal to be discarded,
2315 * whether or not it is blocked."
2317 * "Setting a signal action to SIG_DFL for a signal that is
2318 * pending and whose default action is to ignore the signal
2319 * (for example, SIGCHLD), shall cause the pending signal to
2320 * be discarded, whether or not it is blocked"
2322 if (act->sa.sa_handler == SIG_IGN ||
2323 (act->sa.sa_handler == SIG_DFL &&
2324 sig_kernel_ignore(sig))) {
2326 * This is a fairly rare case, so we only take the
2327 * tasklist_lock once we're sure we'll need it.
2328 * Now we must do this little unlock and relock
2329 * dance to maintain the lock hierarchy.
2331 struct task_struct *t = current;
2332 spin_unlock_irq(&t->sighand->siglock);
2333 read_lock(&tasklist_lock);
2334 spin_lock_irq(&t->sighand->siglock);
2336 sigdelsetmask(&k->sa.sa_mask,
2337 sigmask(SIGKILL) | sigmask(SIGSTOP));
2338 rm_from_queue(sigmask(sig), &t->signal->shared_pending);
2340 rm_from_queue(sigmask(sig), &t->pending);
2341 recalc_sigpending_tsk(t);
2343 } while (t != current);
2344 spin_unlock_irq(¤t->sighand->siglock);
2345 read_unlock(&tasklist_lock);
2350 sigdelsetmask(&k->sa.sa_mask,
2351 sigmask(SIGKILL) | sigmask(SIGSTOP));
2354 spin_unlock_irq(¤t->sighand->siglock);
2359 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
2365 oss.ss_sp = (void __user *) current->sas_ss_sp;
2366 oss.ss_size = current->sas_ss_size;
2367 oss.ss_flags = sas_ss_flags(sp);
2376 if (verify_area(VERIFY_READ, uss, sizeof(*uss))
2377 || __get_user(ss_sp, &uss->ss_sp)
2378 || __get_user(ss_flags, &uss->ss_flags)
2379 || __get_user(ss_size, &uss->ss_size))
2383 if (on_sig_stack(sp))
2389 * Note - this code used to test ss_flags incorrectly
2390 * old code may have been written using ss_flags==0
2391 * to mean ss_flags==SS_ONSTACK (as this was the only
2392 * way that worked) - this fix preserves that older
2395 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
2398 if (ss_flags == SS_DISABLE) {
2403 if (ss_size < MINSIGSTKSZ)
2407 current->sas_ss_sp = (unsigned long) ss_sp;
2408 current->sas_ss_size = ss_size;
2413 if (copy_to_user(uoss, &oss, sizeof(oss)))
2422 #ifdef __ARCH_WANT_SYS_SIGPENDING
2425 sys_sigpending(old_sigset_t __user *set)
2427 return do_sigpending(set, sizeof(*set));
2432 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
2433 /* Some platforms have their own version with special arguments others
2434 support only sys_rt_sigprocmask. */
2437 sys_sigprocmask(int how, old_sigset_t __user *set, old_sigset_t __user *oset)
2440 old_sigset_t old_set, new_set;
2444 if (copy_from_user(&new_set, set, sizeof(*set)))
2446 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
2448 spin_lock_irq(¤t->sighand->siglock);
2449 old_set = current->blocked.sig[0];
2457 sigaddsetmask(¤t->blocked, new_set);
2460 sigdelsetmask(¤t->blocked, new_set);
2463 current->blocked.sig[0] = new_set;
2467 recalc_sigpending();
2468 spin_unlock_irq(¤t->sighand->siglock);
2474 old_set = current->blocked.sig[0];
2477 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2484 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
2486 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
2488 sys_rt_sigaction(int sig,
2489 const struct sigaction __user *act,
2490 struct sigaction __user *oact,
2493 struct k_sigaction new_sa, old_sa;
2496 /* XXX: Don't preclude handling different sized sigset_t's. */
2497 if (sigsetsize != sizeof(sigset_t))
2501 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
2505 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
2508 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
2514 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
2516 #ifdef __ARCH_WANT_SYS_SGETMASK
2519 * For backwards compatibility. Functionality superseded by sigprocmask.
2525 return current->blocked.sig[0];
2529 sys_ssetmask(int newmask)
2533 spin_lock_irq(¤t->sighand->siglock);
2534 old = current->blocked.sig[0];
2536 siginitset(¤t->blocked, newmask & ~(sigmask(SIGKILL)|
2538 recalc_sigpending();
2539 spin_unlock_irq(¤t->sighand->siglock);
2543 #endif /* __ARCH_WANT_SGETMASK */
2545 #ifdef __ARCH_WANT_SYS_SIGNAL
2547 * For backwards compatibility. Functionality superseded by sigaction.
2549 asmlinkage unsigned long
2550 sys_signal(int sig, __sighandler_t handler)
2552 struct k_sigaction new_sa, old_sa;
2555 new_sa.sa.sa_handler = handler;
2556 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
2558 ret = do_sigaction(sig, &new_sa, &old_sa);
2560 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
2562 #endif /* __ARCH_WANT_SYS_SIGNAL */
2564 #ifdef __ARCH_WANT_SYS_PAUSE
2569 current->state = TASK_INTERRUPTIBLE;
2571 return -ERESTARTNOHAND;
2576 void __init signals_init(void)
2579 kmem_cache_create("sigqueue",
2580 sizeof(struct sigqueue),
2581 __alignof__(struct sigqueue),
2582 SLAB_PANIC, NULL, NULL);