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/syscalls.h>
24 #include <linux/ptrace.h>
25 #include <linux/posix-timers.h>
26 #include <linux/signal.h>
27 #include <linux/audit.h>
28 #include <asm/param.h>
29 #include <asm/uaccess.h>
30 #include <asm/unistd.h>
31 #include <asm/siginfo.h>
34 * SLAB caches for signal bits.
37 static kmem_cache_t *sigqueue_cachep;
40 * In POSIX a signal is sent either to a specific thread (Linux task)
41 * or to the process as a whole (Linux thread group). How the signal
42 * is sent determines whether it's to one thread or the whole group,
43 * which determines which signal mask(s) are involved in blocking it
44 * from being delivered until later. When the signal is delivered,
45 * either it's caught or ignored by a user handler or it has a default
46 * effect that applies to the whole thread group (POSIX process).
48 * The possible effects an unblocked signal set to SIG_DFL can have are:
49 * ignore - Nothing Happens
50 * terminate - kill the process, i.e. all threads in the group,
51 * similar to exit_group. The group leader (only) reports
52 * WIFSIGNALED status to its parent.
53 * coredump - write a core dump file describing all threads using
54 * the same mm and then kill all those threads
55 * stop - stop all the threads in the group, i.e. TASK_STOPPED state
57 * SIGKILL and SIGSTOP cannot be caught, blocked, or ignored.
58 * Other signals when not blocked and set to SIG_DFL behaves as follows.
59 * The job control signals also have other special effects.
61 * +--------------------+------------------+
62 * | POSIX signal | default action |
63 * +--------------------+------------------+
64 * | SIGHUP | terminate |
65 * | SIGINT | terminate |
66 * | SIGQUIT | coredump |
67 * | SIGILL | coredump |
68 * | SIGTRAP | coredump |
69 * | SIGABRT/SIGIOT | coredump |
70 * | SIGBUS | coredump |
71 * | SIGFPE | coredump |
72 * | SIGKILL | terminate(+) |
73 * | SIGUSR1 | terminate |
74 * | SIGSEGV | coredump |
75 * | SIGUSR2 | terminate |
76 * | SIGPIPE | terminate |
77 * | SIGALRM | terminate |
78 * | SIGTERM | terminate |
79 * | SIGCHLD | ignore |
80 * | SIGCONT | ignore(*) |
81 * | SIGSTOP | stop(*)(+) |
82 * | SIGTSTP | stop(*) |
83 * | SIGTTIN | stop(*) |
84 * | SIGTTOU | stop(*) |
86 * | SIGXCPU | coredump |
87 * | SIGXFSZ | coredump |
88 * | SIGVTALRM | terminate |
89 * | SIGPROF | terminate |
90 * | SIGPOLL/SIGIO | terminate |
91 * | SIGSYS/SIGUNUSED | coredump |
92 * | SIGSTKFLT | terminate |
93 * | SIGWINCH | ignore |
94 * | SIGPWR | terminate |
95 * | SIGRTMIN-SIGRTMAX | terminate |
96 * +--------------------+------------------+
97 * | non-POSIX signal | default action |
98 * +--------------------+------------------+
99 * | SIGEMT | coredump |
100 * +--------------------+------------------+
102 * (+) For SIGKILL and SIGSTOP the action is "always", not just "default".
103 * (*) Special job control effects:
104 * When SIGCONT is sent, it resumes the process (all threads in the group)
105 * from TASK_STOPPED state and also clears any pending/queued stop signals
106 * (any of those marked with "stop(*)"). This happens regardless of blocking,
107 * catching, or ignoring SIGCONT. When any stop signal is sent, it clears
108 * any pending/queued SIGCONT signals; this happens regardless of blocking,
109 * catching, or ignored the stop signal, though (except for SIGSTOP) the
110 * default action of stopping the process may happen later or never.
114 #define M_SIGEMT M(SIGEMT)
119 #if SIGRTMIN > BITS_PER_LONG
120 #define M(sig) (1ULL << ((sig)-1))
122 #define M(sig) (1UL << ((sig)-1))
124 #define T(sig, mask) (M(sig) & (mask))
126 #define SIG_KERNEL_ONLY_MASK (\
127 M(SIGKILL) | M(SIGSTOP) )
129 #define SIG_KERNEL_STOP_MASK (\
130 M(SIGSTOP) | M(SIGTSTP) | M(SIGTTIN) | M(SIGTTOU) )
132 #define SIG_KERNEL_COREDUMP_MASK (\
133 M(SIGQUIT) | M(SIGILL) | M(SIGTRAP) | M(SIGABRT) | \
134 M(SIGFPE) | M(SIGSEGV) | M(SIGBUS) | M(SIGSYS) | \
135 M(SIGXCPU) | M(SIGXFSZ) | M_SIGEMT )
137 #define SIG_KERNEL_IGNORE_MASK (\
138 M(SIGCONT) | M(SIGCHLD) | M(SIGWINCH) | M(SIGURG) )
140 #define sig_kernel_only(sig) \
141 (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_ONLY_MASK))
142 #define sig_kernel_coredump(sig) \
143 (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_COREDUMP_MASK))
144 #define sig_kernel_ignore(sig) \
145 (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_IGNORE_MASK))
146 #define sig_kernel_stop(sig) \
147 (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_STOP_MASK))
149 #define sig_user_defined(t, signr) \
150 (((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_DFL) && \
151 ((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_IGN))
153 #define sig_fatal(t, signr) \
154 (!T(signr, SIG_KERNEL_IGNORE_MASK|SIG_KERNEL_STOP_MASK) && \
155 (t)->sighand->action[(signr)-1].sa.sa_handler == SIG_DFL)
157 static int sig_ignored(struct task_struct *t, int sig)
159 void __user * handler;
162 * Tracers always want to know about signals..
164 if (t->ptrace & PT_PTRACED)
168 * Blocked signals are never ignored, since the
169 * signal handler may change by the time it is
172 if (sigismember(&t->blocked, sig))
175 /* Is it explicitly or implicitly ignored? */
176 handler = t->sighand->action[sig-1].sa.sa_handler;
177 return handler == SIG_IGN ||
178 (handler == SIG_DFL && sig_kernel_ignore(sig));
182 * Re-calculate pending state from the set of locally pending
183 * signals, globally pending signals, and blocked signals.
185 static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
190 switch (_NSIG_WORDS) {
192 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
193 ready |= signal->sig[i] &~ blocked->sig[i];
196 case 4: ready = signal->sig[3] &~ blocked->sig[3];
197 ready |= signal->sig[2] &~ blocked->sig[2];
198 ready |= signal->sig[1] &~ blocked->sig[1];
199 ready |= signal->sig[0] &~ blocked->sig[0];
202 case 2: ready = signal->sig[1] &~ blocked->sig[1];
203 ready |= signal->sig[0] &~ blocked->sig[0];
206 case 1: ready = signal->sig[0] &~ blocked->sig[0];
211 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
213 fastcall void recalc_sigpending_tsk(struct task_struct *t)
215 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(struct task_struct *t, unsigned int __nocast flags,
268 struct sigqueue *q = NULL;
270 atomic_inc(&t->user->sigpending);
271 if (override_rlimit ||
272 atomic_read(&t->user->sigpending) <=
273 t->signal->rlim[RLIMIT_SIGPENDING].rlim_cur)
274 q = kmem_cache_alloc(sigqueue_cachep, flags);
275 if (unlikely(q == NULL)) {
276 atomic_dec(&t->user->sigpending);
278 INIT_LIST_HEAD(&q->list);
281 q->user = get_uid(t->user);
286 static inline void __sigqueue_free(struct sigqueue *q)
288 if (q->flags & SIGQUEUE_PREALLOC)
290 atomic_dec(&q->user->sigpending);
292 kmem_cache_free(sigqueue_cachep, q);
295 static void flush_sigqueue(struct sigpending *queue)
299 sigemptyset(&queue->signal);
300 while (!list_empty(&queue->list)) {
301 q = list_entry(queue->list.next, struct sigqueue , list);
302 list_del_init(&q->list);
308 * Flush all pending signals for a task.
312 flush_signals(struct task_struct *t)
316 spin_lock_irqsave(&t->sighand->siglock, flags);
317 clear_tsk_thread_flag(t,TIF_SIGPENDING);
318 flush_sigqueue(&t->pending);
319 flush_sigqueue(&t->signal->shared_pending);
320 spin_unlock_irqrestore(&t->sighand->siglock, flags);
324 * This function expects the tasklist_lock write-locked.
326 void __exit_sighand(struct task_struct *tsk)
328 struct sighand_struct * sighand = tsk->sighand;
330 /* Ok, we're done with the signal handlers */
332 if (atomic_dec_and_test(&sighand->count))
333 kmem_cache_free(sighand_cachep, sighand);
336 void exit_sighand(struct task_struct *tsk)
338 write_lock_irq(&tasklist_lock);
340 write_unlock_irq(&tasklist_lock);
344 * This function expects the tasklist_lock write-locked.
346 void __exit_signal(struct task_struct *tsk)
348 struct signal_struct * sig = tsk->signal;
349 struct sighand_struct * sighand = tsk->sighand;
353 if (!atomic_read(&sig->count))
355 spin_lock(&sighand->siglock);
356 posix_cpu_timers_exit(tsk);
357 if (atomic_dec_and_test(&sig->count)) {
358 posix_cpu_timers_exit_group(tsk);
359 if (tsk == sig->curr_target)
360 sig->curr_target = next_thread(tsk);
362 spin_unlock(&sighand->siglock);
363 flush_sigqueue(&sig->shared_pending);
366 * If there is any task waiting for the group exit
369 if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count) {
370 wake_up_process(sig->group_exit_task);
371 sig->group_exit_task = NULL;
373 if (tsk == sig->curr_target)
374 sig->curr_target = next_thread(tsk);
377 * Accumulate here the counters for all threads but the
378 * group leader as they die, so they can be added into
379 * the process-wide totals when those are taken.
380 * The group leader stays around as a zombie as long
381 * as there are other threads. When it gets reaped,
382 * the exit.c code will add its counts into these totals.
383 * We won't ever get here for the group leader, since it
384 * will have been the last reference on the signal_struct.
386 sig->utime = cputime_add(sig->utime, tsk->utime);
387 sig->stime = cputime_add(sig->stime, tsk->stime);
388 sig->min_flt += tsk->min_flt;
389 sig->maj_flt += tsk->maj_flt;
390 sig->nvcsw += tsk->nvcsw;
391 sig->nivcsw += tsk->nivcsw;
392 sig->sched_time += tsk->sched_time;
393 spin_unlock(&sighand->siglock);
394 sig = NULL; /* Marker for below. */
396 clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
397 flush_sigqueue(&tsk->pending);
400 * We are cleaning up the signal_struct here. We delayed
401 * calling exit_itimers until after flush_sigqueue, just in
402 * case our thread-local pending queue contained a queued
403 * timer signal that would have been cleared in
404 * exit_itimers. When that called sigqueue_free, it would
405 * attempt to re-take the tasklist_lock and deadlock. This
406 * can never happen if we ensure that all queues the
407 * timer's signal might be queued on have been flushed
408 * first. The shared_pending queue, and our own pending
409 * queue are the only queues the timer could be on, since
410 * there are no other threads left in the group and timer
411 * signals are constrained to threads inside the group.
414 exit_thread_group_keys(sig);
415 kmem_cache_free(signal_cachep, sig);
419 void exit_signal(struct task_struct *tsk)
421 write_lock_irq(&tasklist_lock);
423 write_unlock_irq(&tasklist_lock);
427 * Flush all handlers for a task.
431 flush_signal_handlers(struct task_struct *t, int force_default)
434 struct k_sigaction *ka = &t->sighand->action[0];
435 for (i = _NSIG ; i != 0 ; i--) {
436 if (force_default || ka->sa.sa_handler != SIG_IGN)
437 ka->sa.sa_handler = SIG_DFL;
439 sigemptyset(&ka->sa.sa_mask);
445 /* Notify the system that a driver wants to block all signals for this
446 * process, and wants to be notified if any signals at all were to be
447 * sent/acted upon. If the notifier routine returns non-zero, then the
448 * signal will be acted upon after all. If the notifier routine returns 0,
449 * then then signal will be blocked. Only one block per process is
450 * allowed. priv is a pointer to private data that the notifier routine
451 * can use to determine if the signal should be blocked or not. */
454 block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
458 spin_lock_irqsave(¤t->sighand->siglock, flags);
459 current->notifier_mask = mask;
460 current->notifier_data = priv;
461 current->notifier = notifier;
462 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
465 /* Notify the system that blocking has ended. */
468 unblock_all_signals(void)
472 spin_lock_irqsave(¤t->sighand->siglock, flags);
473 current->notifier = NULL;
474 current->notifier_data = NULL;
476 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
479 static inline int collect_signal(int sig, struct sigpending *list, siginfo_t *info)
481 struct sigqueue *q, *first = NULL;
482 int still_pending = 0;
484 if (unlikely(!sigismember(&list->signal, sig)))
488 * Collect the siginfo appropriate to this signal. Check if
489 * there is another siginfo for the same signal.
491 list_for_each_entry(q, &list->list, list) {
492 if (q->info.si_signo == sig) {
501 list_del_init(&first->list);
502 copy_siginfo(info, &first->info);
503 __sigqueue_free(first);
505 sigdelset(&list->signal, sig);
508 /* Ok, it wasn't in the queue. This must be
509 a fast-pathed signal or we must have been
510 out of queue space. So zero out the info.
512 sigdelset(&list->signal, sig);
513 info->si_signo = sig;
522 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
527 /* SIGKILL must have priority, otherwise it is quite easy
528 * to create an unkillable process, sending sig < SIGKILL
530 if (unlikely(sigismember(&pending->signal, SIGKILL))) {
531 if (!sigismember(mask, SIGKILL))
536 sig = next_signal(pending, mask);
538 if (current->notifier) {
539 if (sigismember(current->notifier_mask, sig)) {
540 if (!(current->notifier)(current->notifier_data)) {
541 clear_thread_flag(TIF_SIGPENDING);
547 if (!collect_signal(sig, pending, info))
557 * Dequeue a signal and return the element to the caller, which is
558 * expected to free it.
560 * All callers have to hold the siglock.
562 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
564 int signr = __dequeue_signal(&tsk->pending, mask, info);
566 signr = __dequeue_signal(&tsk->signal->shared_pending,
568 if (signr && unlikely(sig_kernel_stop(signr))) {
570 * Set a marker that we have dequeued a stop signal. Our
571 * caller might release the siglock and then the pending
572 * stop signal it is about to process is no longer in the
573 * pending bitmasks, but must still be cleared by a SIGCONT
574 * (and overruled by a SIGKILL). So those cases clear this
575 * shared flag after we've set it. Note that this flag may
576 * remain set after the signal we return is ignored or
577 * handled. That doesn't matter because its only purpose
578 * is to alert stop-signal processing code when another
579 * processor has come along and cleared the flag.
581 tsk->signal->flags |= SIGNAL_STOP_DEQUEUED;
584 ((info->si_code & __SI_MASK) == __SI_TIMER) &&
585 info->si_sys_private){
587 * Release the siglock to ensure proper locking order
588 * of timer locks outside of siglocks. Note, we leave
589 * irqs disabled here, since the posix-timers code is
590 * about to disable them again anyway.
592 spin_unlock(&tsk->sighand->siglock);
593 do_schedule_next_timer(info);
594 spin_lock(&tsk->sighand->siglock);
600 * Tell a process that it has a new active signal..
602 * NOTE! we rely on the previous spin_lock to
603 * lock interrupts for us! We can only be called with
604 * "siglock" held, and the local interrupt must
605 * have been disabled when that got acquired!
607 * No need to set need_resched since signal event passing
608 * goes through ->blocked
610 void signal_wake_up(struct task_struct *t, int resume)
614 set_tsk_thread_flag(t, TIF_SIGPENDING);
617 * For SIGKILL, we want to wake it up in the stopped/traced case.
618 * We don't check t->state here because there is a race with it
619 * executing another processor and just now entering stopped state.
620 * By using wake_up_state, we ensure the process will wake up and
621 * handle its death signal.
623 mask = TASK_INTERRUPTIBLE;
625 mask |= TASK_STOPPED | TASK_TRACED;
626 if (!wake_up_state(t, mask))
631 * Remove signals in mask from the pending set and queue.
632 * Returns 1 if any signals were found.
634 * All callers must be holding the siglock.
636 static int rm_from_queue(unsigned long mask, struct sigpending *s)
638 struct sigqueue *q, *n;
640 if (!sigtestsetmask(&s->signal, mask))
643 sigdelsetmask(&s->signal, mask);
644 list_for_each_entry_safe(q, n, &s->list, list) {
645 if (q->info.si_signo < SIGRTMIN &&
646 (mask & sigmask(q->info.si_signo))) {
647 list_del_init(&q->list);
655 * Bad permissions for sending the signal
657 static int check_kill_permission(int sig, struct siginfo *info,
658 struct task_struct *t)
661 if (!valid_signal(sig))
664 if ((!info || ((unsigned long)info != 1 &&
665 (unsigned long)info != 2 && SI_FROMUSER(info)))
666 && ((sig != SIGCONT) ||
667 (current->signal->session != t->signal->session))
668 && (current->euid ^ t->suid) && (current->euid ^ t->uid)
669 && (current->uid ^ t->suid) && (current->uid ^ t->uid)
670 && !capable(CAP_KILL))
673 error = security_task_kill(t, info, sig);
675 audit_signal_info(sig, t); /* Let audit system see the signal */
680 static void do_notify_parent_cldstop(struct task_struct *tsk,
685 * Handle magic process-wide effects of stop/continue signals.
686 * Unlike the signal actions, these happen immediately at signal-generation
687 * time regardless of blocking, ignoring, or handling. This does the
688 * actual continuing for SIGCONT, but not the actual stopping for stop
689 * signals. The process stop is done as a signal action for SIG_DFL.
691 static void handle_stop_signal(int sig, struct task_struct *p)
693 struct task_struct *t;
695 if (p->signal->flags & SIGNAL_GROUP_EXIT)
697 * The process is in the middle of dying already.
701 if (sig_kernel_stop(sig)) {
703 * This is a stop signal. Remove SIGCONT from all queues.
705 rm_from_queue(sigmask(SIGCONT), &p->signal->shared_pending);
708 rm_from_queue(sigmask(SIGCONT), &t->pending);
711 } else if (sig == SIGCONT) {
713 * Remove all stop signals from all queues,
714 * and wake all threads.
716 if (unlikely(p->signal->group_stop_count > 0)) {
718 * There was a group stop in progress. We'll
719 * pretend it finished before we got here. We are
720 * obliged to report it to the parent: if the
721 * SIGSTOP happened "after" this SIGCONT, then it
722 * would have cleared this pending SIGCONT. If it
723 * happened "before" this SIGCONT, then the parent
724 * got the SIGCHLD about the stop finishing before
725 * the continue happened. We do the notification
726 * now, and it's as if the stop had finished and
727 * the SIGCHLD was pending on entry to this kill.
729 p->signal->group_stop_count = 0;
730 p->signal->flags = SIGNAL_STOP_CONTINUED;
731 spin_unlock(&p->sighand->siglock);
732 do_notify_parent_cldstop(p, (p->ptrace & PT_PTRACED), CLD_STOPPED);
733 spin_lock(&p->sighand->siglock);
735 rm_from_queue(SIG_KERNEL_STOP_MASK, &p->signal->shared_pending);
739 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
742 * If there is a handler for SIGCONT, we must make
743 * sure that no thread returns to user mode before
744 * we post the signal, in case it was the only
745 * thread eligible to run the signal handler--then
746 * it must not do anything between resuming and
747 * running the handler. With the TIF_SIGPENDING
748 * flag set, the thread will pause and acquire the
749 * siglock that we hold now and until we've queued
750 * the pending signal.
752 * Wake up the stopped thread _after_ setting
755 state = TASK_STOPPED;
756 if (sig_user_defined(t, SIGCONT) && !sigismember(&t->blocked, SIGCONT)) {
757 set_tsk_thread_flag(t, TIF_SIGPENDING);
758 state |= TASK_INTERRUPTIBLE;
760 wake_up_state(t, state);
765 if (p->signal->flags & SIGNAL_STOP_STOPPED) {
767 * We were in fact stopped, and are now continued.
768 * Notify the parent with CLD_CONTINUED.
770 p->signal->flags = SIGNAL_STOP_CONTINUED;
771 p->signal->group_exit_code = 0;
772 spin_unlock(&p->sighand->siglock);
773 do_notify_parent_cldstop(p, (p->ptrace & PT_PTRACED), CLD_CONTINUED);
774 spin_lock(&p->sighand->siglock);
777 * We are not stopped, but there could be a stop
778 * signal in the middle of being processed after
779 * being removed from the queue. Clear that too.
781 p->signal->flags = 0;
783 } else if (sig == SIGKILL) {
785 * Make sure that any pending stop signal already dequeued
786 * is undone by the wakeup for SIGKILL.
788 p->signal->flags = 0;
792 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
793 struct sigpending *signals)
795 struct sigqueue * q = NULL;
799 * fast-pathed signals for kernel-internal things like SIGSTOP
802 if ((unsigned long)info == 2)
805 /* Real-time signals must be queued if sent by sigqueue, or
806 some other real-time mechanism. It is implementation
807 defined whether kill() does so. We attempt to do so, on
808 the principle of least surprise, but since kill is not
809 allowed to fail with EAGAIN when low on memory we just
810 make sure at least one signal gets delivered and don't
811 pass on the info struct. */
813 q = __sigqueue_alloc(t, GFP_ATOMIC, (sig < SIGRTMIN &&
814 ((unsigned long) info < 2 ||
815 info->si_code >= 0)));
817 list_add_tail(&q->list, &signals->list);
818 switch ((unsigned long) info) {
820 q->info.si_signo = sig;
821 q->info.si_errno = 0;
822 q->info.si_code = SI_USER;
823 q->info.si_pid = current->pid;
824 q->info.si_uid = current->uid;
827 q->info.si_signo = sig;
828 q->info.si_errno = 0;
829 q->info.si_code = SI_KERNEL;
834 copy_siginfo(&q->info, info);
838 if (sig >= SIGRTMIN && info && (unsigned long)info != 1
839 && info->si_code != SI_USER)
841 * Queue overflow, abort. We may abort if the signal was rt
842 * and sent by user using something other than kill().
845 if (((unsigned long)info > 1) && (info->si_code == SI_TIMER))
847 * Set up a return to indicate that we dropped
850 ret = info->si_sys_private;
854 sigaddset(&signals->signal, sig);
858 #define LEGACY_QUEUE(sigptr, sig) \
859 (((sig) < SIGRTMIN) && sigismember(&(sigptr)->signal, (sig)))
863 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
867 if (!irqs_disabled())
869 assert_spin_locked(&t->sighand->siglock);
871 if (((unsigned long)info > 2) && (info->si_code == SI_TIMER))
873 * Set up a return to indicate that we dropped the signal.
875 ret = info->si_sys_private;
877 /* Short-circuit ignored signals. */
878 if (sig_ignored(t, sig))
881 /* Support queueing exactly one non-rt signal, so that we
882 can get more detailed information about the cause of
884 if (LEGACY_QUEUE(&t->pending, sig))
887 ret = send_signal(sig, info, t, &t->pending);
888 if (!ret && !sigismember(&t->blocked, sig))
889 signal_wake_up(t, sig == SIGKILL);
895 * Force a signal that the process can't ignore: if necessary
896 * we unblock the signal and change any SIG_IGN to SIG_DFL.
900 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
902 unsigned long int flags;
905 spin_lock_irqsave(&t->sighand->siglock, flags);
906 if (sigismember(&t->blocked, sig) || t->sighand->action[sig-1].sa.sa_handler == SIG_IGN) {
907 t->sighand->action[sig-1].sa.sa_handler = SIG_DFL;
908 sigdelset(&t->blocked, sig);
909 recalc_sigpending_tsk(t);
911 ret = specific_send_sig_info(sig, info, t);
912 spin_unlock_irqrestore(&t->sighand->siglock, flags);
918 force_sig_specific(int sig, struct task_struct *t)
920 unsigned long int flags;
922 spin_lock_irqsave(&t->sighand->siglock, flags);
923 if (t->sighand->action[sig-1].sa.sa_handler == SIG_IGN)
924 t->sighand->action[sig-1].sa.sa_handler = SIG_DFL;
925 sigdelset(&t->blocked, sig);
926 recalc_sigpending_tsk(t);
927 specific_send_sig_info(sig, (void *)2, t);
928 spin_unlock_irqrestore(&t->sighand->siglock, flags);
932 * Test if P wants to take SIG. After we've checked all threads with this,
933 * it's equivalent to finding no threads not blocking SIG. Any threads not
934 * blocking SIG were ruled out because they are not running and already
935 * have pending signals. Such threads will dequeue from the shared queue
936 * as soon as they're available, so putting the signal on the shared queue
937 * will be equivalent to sending it to one such thread.
939 #define wants_signal(sig, p, mask) \
940 (!sigismember(&(p)->blocked, sig) \
941 && !((p)->state & mask) \
942 && !((p)->flags & PF_EXITING) \
943 && (task_curr(p) || !signal_pending(p)))
947 __group_complete_signal(int sig, struct task_struct *p)
950 struct task_struct *t;
953 * Don't bother traced and stopped tasks (but
954 * SIGKILL will punch through that).
956 mask = TASK_STOPPED | TASK_TRACED;
961 * Now find a thread we can wake up to take the signal off the queue.
963 * If the main thread wants the signal, it gets first crack.
964 * Probably the least surprising to the average bear.
966 if (wants_signal(sig, p, mask))
968 else if (thread_group_empty(p))
970 * There is just one thread and it does not need to be woken.
971 * It will dequeue unblocked signals before it runs again.
976 * Otherwise try to find a suitable thread.
978 t = p->signal->curr_target;
980 /* restart balancing at this thread */
981 t = p->signal->curr_target = p;
982 BUG_ON(t->tgid != p->tgid);
984 while (!wants_signal(sig, t, mask)) {
986 if (t == p->signal->curr_target)
988 * No thread needs to be woken.
989 * Any eligible threads will see
990 * the signal in the queue soon.
994 p->signal->curr_target = t;
998 * Found a killable thread. If the signal will be fatal,
999 * then start taking the whole group down immediately.
1001 if (sig_fatal(p, sig) && !(p->signal->flags & SIGNAL_GROUP_EXIT) &&
1002 !sigismember(&t->real_blocked, sig) &&
1003 (sig == SIGKILL || !(t->ptrace & PT_PTRACED))) {
1005 * This signal will be fatal to the whole group.
1007 if (!sig_kernel_coredump(sig)) {
1009 * Start a group exit and wake everybody up.
1010 * This way we don't have other threads
1011 * running and doing things after a slower
1012 * thread has the fatal signal pending.
1014 p->signal->flags = SIGNAL_GROUP_EXIT;
1015 p->signal->group_exit_code = sig;
1016 p->signal->group_stop_count = 0;
1019 sigaddset(&t->pending.signal, SIGKILL);
1020 signal_wake_up(t, 1);
1027 * There will be a core dump. We make all threads other
1028 * than the chosen one go into a group stop so that nothing
1029 * happens until it gets scheduled, takes the signal off
1030 * the shared queue, and does the core dump. This is a
1031 * little more complicated than strictly necessary, but it
1032 * keeps the signal state that winds up in the core dump
1033 * unchanged from the death state, e.g. which thread had
1034 * the core-dump signal unblocked.
1036 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
1037 rm_from_queue(SIG_KERNEL_STOP_MASK, &p->signal->shared_pending);
1038 p->signal->group_stop_count = 0;
1039 p->signal->group_exit_task = t;
1042 p->signal->group_stop_count++;
1043 signal_wake_up(t, 0);
1046 wake_up_process(p->signal->group_exit_task);
1051 * The signal is already in the shared-pending queue.
1052 * Tell the chosen thread to wake up and dequeue it.
1054 signal_wake_up(t, sig == SIGKILL);
1059 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1063 assert_spin_locked(&p->sighand->siglock);
1064 handle_stop_signal(sig, p);
1066 if (((unsigned long)info > 2) && (info->si_code == SI_TIMER))
1068 * Set up a return to indicate that we dropped the signal.
1070 ret = info->si_sys_private;
1072 /* Short-circuit ignored signals. */
1073 if (sig_ignored(p, sig))
1076 if (LEGACY_QUEUE(&p->signal->shared_pending, sig))
1077 /* This is a non-RT signal and we already have one queued. */
1081 * Put this signal on the shared-pending queue, or fail with EAGAIN.
1082 * We always use the shared queue for process-wide signals,
1083 * to avoid several races.
1085 ret = send_signal(sig, info, p, &p->signal->shared_pending);
1089 __group_complete_signal(sig, p);
1094 * Nuke all other threads in the group.
1096 void zap_other_threads(struct task_struct *p)
1098 struct task_struct *t;
1100 p->signal->flags = SIGNAL_GROUP_EXIT;
1101 p->signal->group_stop_count = 0;
1103 if (thread_group_empty(p))
1106 for (t = next_thread(p); t != p; t = next_thread(t)) {
1108 * Don't bother with already dead threads
1114 * We don't want to notify the parent, since we are
1115 * killed as part of a thread group due to another
1116 * thread doing an execve() or similar. So set the
1117 * exit signal to -1 to allow immediate reaping of
1118 * the process. But don't detach the thread group
1121 if (t != p->group_leader)
1122 t->exit_signal = -1;
1124 sigaddset(&t->pending.signal, SIGKILL);
1125 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
1126 signal_wake_up(t, 1);
1131 * Must be called with the tasklist_lock held for reading!
1133 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1135 unsigned long flags;
1138 ret = check_kill_permission(sig, info, p);
1139 if (!ret && sig && p->sighand) {
1140 spin_lock_irqsave(&p->sighand->siglock, flags);
1141 ret = __group_send_sig_info(sig, info, p);
1142 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1149 * kill_pg_info() sends a signal to a process group: this is what the tty
1150 * control characters do (^C, ^Z etc)
1153 int __kill_pg_info(int sig, struct siginfo *info, pid_t pgrp)
1155 struct task_struct *p = NULL;
1156 int retval, success;
1163 do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
1164 int err = group_send_sig_info(sig, info, p);
1167 } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
1168 return success ? 0 : retval;
1172 kill_pg_info(int sig, struct siginfo *info, pid_t pgrp)
1176 read_lock(&tasklist_lock);
1177 retval = __kill_pg_info(sig, info, pgrp);
1178 read_unlock(&tasklist_lock);
1184 kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1187 struct task_struct *p;
1189 read_lock(&tasklist_lock);
1190 p = find_task_by_pid(pid);
1193 error = group_send_sig_info(sig, info, p);
1194 read_unlock(&tasklist_lock);
1200 * kill_something_info() interprets pid in interesting ways just like kill(2).
1202 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1203 * is probably wrong. Should make it like BSD or SYSV.
1206 static int kill_something_info(int sig, struct siginfo *info, int pid)
1209 return kill_pg_info(sig, info, process_group(current));
1210 } else if (pid == -1) {
1211 int retval = 0, count = 0;
1212 struct task_struct * p;
1214 read_lock(&tasklist_lock);
1215 for_each_process(p) {
1216 if (p->pid > 1 && p->tgid != current->tgid) {
1217 int err = group_send_sig_info(sig, info, p);
1223 read_unlock(&tasklist_lock);
1224 return count ? retval : -ESRCH;
1225 } else if (pid < 0) {
1226 return kill_pg_info(sig, info, -pid);
1228 return kill_proc_info(sig, info, pid);
1233 * These are for backward compatibility with the rest of the kernel source.
1237 * These two are the most common entry points. They send a signal
1238 * just to the specific thread.
1241 send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1244 unsigned long flags;
1247 * Make sure legacy kernel users don't send in bad values
1248 * (normal paths check this in check_kill_permission).
1250 if (!valid_signal(sig))
1254 * We need the tasklist lock even for the specific
1255 * thread case (when we don't need to follow the group
1256 * lists) in order to avoid races with "p->sighand"
1257 * going away or changing from under us.
1259 read_lock(&tasklist_lock);
1260 spin_lock_irqsave(&p->sighand->siglock, flags);
1261 ret = specific_send_sig_info(sig, info, p);
1262 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1263 read_unlock(&tasklist_lock);
1268 send_sig(int sig, struct task_struct *p, int priv)
1270 return send_sig_info(sig, (void*)(long)(priv != 0), p);
1274 * This is the entry point for "process-wide" signals.
1275 * They will go to an appropriate thread in the thread group.
1278 send_group_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1281 read_lock(&tasklist_lock);
1282 ret = group_send_sig_info(sig, info, p);
1283 read_unlock(&tasklist_lock);
1288 force_sig(int sig, struct task_struct *p)
1290 force_sig_info(sig, (void*)1L, p);
1294 * When things go south during signal handling, we
1295 * will force a SIGSEGV. And if the signal that caused
1296 * the problem was already a SIGSEGV, we'll want to
1297 * make sure we don't even try to deliver the signal..
1300 force_sigsegv(int sig, struct task_struct *p)
1302 if (sig == SIGSEGV) {
1303 unsigned long flags;
1304 spin_lock_irqsave(&p->sighand->siglock, flags);
1305 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1306 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1308 force_sig(SIGSEGV, p);
1313 kill_pg(pid_t pgrp, int sig, int priv)
1315 return kill_pg_info(sig, (void *)(long)(priv != 0), pgrp);
1319 kill_proc(pid_t pid, int sig, int priv)
1321 return kill_proc_info(sig, (void *)(long)(priv != 0), pid);
1325 * These functions support sending signals using preallocated sigqueue
1326 * structures. This is needed "because realtime applications cannot
1327 * afford to lose notifications of asynchronous events, like timer
1328 * expirations or I/O completions". In the case of Posix Timers
1329 * we allocate the sigqueue structure from the timer_create. If this
1330 * allocation fails we are able to report the failure to the application
1331 * with an EAGAIN error.
1334 struct sigqueue *sigqueue_alloc(void)
1338 if ((q = __sigqueue_alloc(current, GFP_KERNEL, 0)))
1339 q->flags |= SIGQUEUE_PREALLOC;
1343 void sigqueue_free(struct sigqueue *q)
1345 unsigned long flags;
1346 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1348 * If the signal is still pending remove it from the
1351 if (unlikely(!list_empty(&q->list))) {
1352 read_lock(&tasklist_lock);
1353 spin_lock_irqsave(q->lock, flags);
1354 if (!list_empty(&q->list))
1355 list_del_init(&q->list);
1356 spin_unlock_irqrestore(q->lock, flags);
1357 read_unlock(&tasklist_lock);
1359 q->flags &= ~SIGQUEUE_PREALLOC;
1364 send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
1366 unsigned long flags;
1370 * We need the tasklist lock even for the specific
1371 * thread case (when we don't need to follow the group
1372 * lists) in order to avoid races with "p->sighand"
1373 * going away or changing from under us.
1375 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1376 read_lock(&tasklist_lock);
1377 spin_lock_irqsave(&p->sighand->siglock, flags);
1379 if (unlikely(!list_empty(&q->list))) {
1381 * If an SI_TIMER entry is already queue just increment
1382 * the overrun count.
1384 if (q->info.si_code != SI_TIMER)
1386 q->info.si_overrun++;
1389 /* Short-circuit ignored signals. */
1390 if (sig_ignored(p, sig)) {
1395 q->lock = &p->sighand->siglock;
1396 list_add_tail(&q->list, &p->pending.list);
1397 sigaddset(&p->pending.signal, sig);
1398 if (!sigismember(&p->blocked, sig))
1399 signal_wake_up(p, sig == SIGKILL);
1402 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1403 read_unlock(&tasklist_lock);
1408 send_group_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
1410 unsigned long flags;
1413 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1414 read_lock(&tasklist_lock);
1415 spin_lock_irqsave(&p->sighand->siglock, flags);
1416 handle_stop_signal(sig, p);
1418 /* Short-circuit ignored signals. */
1419 if (sig_ignored(p, sig)) {
1424 if (unlikely(!list_empty(&q->list))) {
1426 * If an SI_TIMER entry is already queue just increment
1427 * the overrun count. Other uses should not try to
1428 * send the signal multiple times.
1430 if (q->info.si_code != SI_TIMER)
1432 q->info.si_overrun++;
1437 * Put this signal on the shared-pending queue.
1438 * We always use the shared queue for process-wide signals,
1439 * to avoid several races.
1441 q->lock = &p->sighand->siglock;
1442 list_add_tail(&q->list, &p->signal->shared_pending.list);
1443 sigaddset(&p->signal->shared_pending.signal, sig);
1445 __group_complete_signal(sig, p);
1447 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1448 read_unlock(&tasklist_lock);
1453 * Wake up any threads in the parent blocked in wait* syscalls.
1455 static inline void __wake_up_parent(struct task_struct *p,
1456 struct task_struct *parent)
1458 wake_up_interruptible_sync(&parent->signal->wait_chldexit);
1462 * Let a parent know about the death of a child.
1463 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1466 void do_notify_parent(struct task_struct *tsk, int sig)
1468 struct siginfo info;
1469 unsigned long flags;
1470 struct sighand_struct *psig;
1474 /* do_notify_parent_cldstop should have been called instead. */
1475 BUG_ON(tsk->state & (TASK_STOPPED|TASK_TRACED));
1477 BUG_ON(!tsk->ptrace &&
1478 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1480 info.si_signo = sig;
1482 info.si_pid = tsk->pid;
1483 info.si_uid = tsk->uid;
1485 /* FIXME: find out whether or not this is supposed to be c*time. */
1486 info.si_utime = cputime_to_jiffies(cputime_add(tsk->utime,
1487 tsk->signal->utime));
1488 info.si_stime = cputime_to_jiffies(cputime_add(tsk->stime,
1489 tsk->signal->stime));
1491 info.si_status = tsk->exit_code & 0x7f;
1492 if (tsk->exit_code & 0x80)
1493 info.si_code = CLD_DUMPED;
1494 else if (tsk->exit_code & 0x7f)
1495 info.si_code = CLD_KILLED;
1497 info.si_code = CLD_EXITED;
1498 info.si_status = tsk->exit_code >> 8;
1501 psig = tsk->parent->sighand;
1502 spin_lock_irqsave(&psig->siglock, flags);
1503 if (sig == SIGCHLD &&
1504 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1505 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1507 * We are exiting and our parent doesn't care. POSIX.1
1508 * defines special semantics for setting SIGCHLD to SIG_IGN
1509 * or setting the SA_NOCLDWAIT flag: we should be reaped
1510 * automatically and not left for our parent's wait4 call.
1511 * Rather than having the parent do it as a magic kind of
1512 * signal handler, we just set this to tell do_exit that we
1513 * can be cleaned up without becoming a zombie. Note that
1514 * we still call __wake_up_parent in this case, because a
1515 * blocked sys_wait4 might now return -ECHILD.
1517 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1518 * is implementation-defined: we do (if you don't want
1519 * it, just use SIG_IGN instead).
1521 tsk->exit_signal = -1;
1522 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1525 if (valid_signal(sig) && sig > 0)
1526 __group_send_sig_info(sig, &info, tsk->parent);
1527 __wake_up_parent(tsk, tsk->parent);
1528 spin_unlock_irqrestore(&psig->siglock, flags);
1531 static void do_notify_parent_cldstop(struct task_struct *tsk, int to_self, int why)
1533 struct siginfo info;
1534 unsigned long flags;
1535 struct task_struct *parent;
1536 struct sighand_struct *sighand;
1539 parent = tsk->parent;
1541 tsk = tsk->group_leader;
1542 parent = tsk->real_parent;
1545 info.si_signo = SIGCHLD;
1547 info.si_pid = tsk->pid;
1548 info.si_uid = tsk->uid;
1550 /* FIXME: find out whether or not this is supposed to be c*time. */
1551 info.si_utime = cputime_to_jiffies(tsk->utime);
1552 info.si_stime = cputime_to_jiffies(tsk->stime);
1557 info.si_status = SIGCONT;
1560 info.si_status = tsk->signal->group_exit_code & 0x7f;
1563 info.si_status = tsk->exit_code & 0x7f;
1569 sighand = parent->sighand;
1570 spin_lock_irqsave(&sighand->siglock, flags);
1571 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1572 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1573 __group_send_sig_info(SIGCHLD, &info, parent);
1575 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1577 __wake_up_parent(tsk, parent);
1578 spin_unlock_irqrestore(&sighand->siglock, flags);
1582 * This must be called with current->sighand->siglock held.
1584 * This should be the path for all ptrace stops.
1585 * We always set current->last_siginfo while stopped here.
1586 * That makes it a way to test a stopped process for
1587 * being ptrace-stopped vs being job-control-stopped.
1589 * If we actually decide not to stop at all because the tracer is gone,
1590 * we leave nostop_code in current->exit_code.
1592 static void ptrace_stop(int exit_code, int nostop_code, siginfo_t *info)
1595 * If there is a group stop in progress,
1596 * we must participate in the bookkeeping.
1598 if (current->signal->group_stop_count > 0)
1599 --current->signal->group_stop_count;
1601 current->last_siginfo = info;
1602 current->exit_code = exit_code;
1604 /* Let the debugger run. */
1605 set_current_state(TASK_TRACED);
1606 spin_unlock_irq(¤t->sighand->siglock);
1607 read_lock(&tasklist_lock);
1608 if (likely(current->ptrace & PT_PTRACED) &&
1609 likely(current->parent != current->real_parent ||
1610 !(current->ptrace & PT_ATTACHED)) &&
1611 (likely(current->parent->signal != current->signal) ||
1612 !unlikely(current->signal->flags & SIGNAL_GROUP_EXIT))) {
1613 do_notify_parent_cldstop(current, 1, CLD_TRAPPED);
1614 read_unlock(&tasklist_lock);
1618 * By the time we got the lock, our tracer went away.
1621 read_unlock(&tasklist_lock);
1622 set_current_state(TASK_RUNNING);
1623 current->exit_code = nostop_code;
1627 * We are back. Now reacquire the siglock before touching
1628 * last_siginfo, so that we are sure to have synchronized with
1629 * any signal-sending on another CPU that wants to examine it.
1631 spin_lock_irq(¤t->sighand->siglock);
1632 current->last_siginfo = NULL;
1635 * Queued signals ignored us while we were stopped for tracing.
1636 * So check for any that we should take before resuming user mode.
1638 recalc_sigpending();
1641 void ptrace_notify(int exit_code)
1645 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1647 memset(&info, 0, sizeof info);
1648 info.si_signo = SIGTRAP;
1649 info.si_code = exit_code;
1650 info.si_pid = current->pid;
1651 info.si_uid = current->uid;
1653 /* Let the debugger run. */
1654 spin_lock_irq(¤t->sighand->siglock);
1655 ptrace_stop(exit_code, 0, &info);
1656 spin_unlock_irq(¤t->sighand->siglock);
1660 finish_stop(int stop_count)
1665 * If there are no other threads in the group, or if there is
1666 * a group stop in progress and we are the last to stop,
1667 * report to the parent. When ptraced, every thread reports itself.
1669 if (stop_count < 0 || (current->ptrace & PT_PTRACED))
1671 else if (stop_count == 0)
1676 read_lock(&tasklist_lock);
1677 do_notify_parent_cldstop(current, to_self, CLD_STOPPED);
1678 read_unlock(&tasklist_lock);
1683 * Now we don't run again until continued.
1685 current->exit_code = 0;
1689 * This performs the stopping for SIGSTOP and other stop signals.
1690 * We have to stop all threads in the thread group.
1691 * Returns nonzero if we've actually stopped and released the siglock.
1692 * Returns zero if we didn't stop and still hold the siglock.
1695 do_signal_stop(int signr)
1697 struct signal_struct *sig = current->signal;
1698 struct sighand_struct *sighand = current->sighand;
1699 int stop_count = -1;
1701 if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED))
1704 if (sig->group_stop_count > 0) {
1706 * There is a group stop in progress. We don't need to
1707 * start another one.
1709 signr = sig->group_exit_code;
1710 stop_count = --sig->group_stop_count;
1711 current->exit_code = signr;
1712 set_current_state(TASK_STOPPED);
1713 if (stop_count == 0)
1714 sig->flags = SIGNAL_STOP_STOPPED;
1715 spin_unlock_irq(&sighand->siglock);
1717 else if (thread_group_empty(current)) {
1719 * Lock must be held through transition to stopped state.
1721 current->exit_code = current->signal->group_exit_code = signr;
1722 set_current_state(TASK_STOPPED);
1723 sig->flags = SIGNAL_STOP_STOPPED;
1724 spin_unlock_irq(&sighand->siglock);
1728 * There is no group stop already in progress.
1729 * We must initiate one now, but that requires
1730 * dropping siglock to get both the tasklist lock
1731 * and siglock again in the proper order. Note that
1732 * this allows an intervening SIGCONT to be posted.
1733 * We need to check for that and bail out if necessary.
1735 struct task_struct *t;
1737 spin_unlock_irq(&sighand->siglock);
1739 /* signals can be posted during this window */
1741 read_lock(&tasklist_lock);
1742 spin_lock_irq(&sighand->siglock);
1744 if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED)) {
1746 * Another stop or continue happened while we
1747 * didn't have the lock. We can just swallow this
1748 * signal now. If we raced with a SIGCONT, that
1749 * should have just cleared it now. If we raced
1750 * with another processor delivering a stop signal,
1751 * then the SIGCONT that wakes us up should clear it.
1753 read_unlock(&tasklist_lock);
1757 if (sig->group_stop_count == 0) {
1758 sig->group_exit_code = signr;
1760 for (t = next_thread(current); t != current;
1763 * Setting state to TASK_STOPPED for a group
1764 * stop is always done with the siglock held,
1765 * so this check has no races.
1767 if (t->state < TASK_STOPPED) {
1769 signal_wake_up(t, 0);
1771 sig->group_stop_count = stop_count;
1774 /* A race with another thread while unlocked. */
1775 signr = sig->group_exit_code;
1776 stop_count = --sig->group_stop_count;
1779 current->exit_code = signr;
1780 set_current_state(TASK_STOPPED);
1781 if (stop_count == 0)
1782 sig->flags = SIGNAL_STOP_STOPPED;
1784 spin_unlock_irq(&sighand->siglock);
1785 read_unlock(&tasklist_lock);
1788 finish_stop(stop_count);
1793 * Do appropriate magic when group_stop_count > 0.
1794 * We return nonzero if we stopped, after releasing the siglock.
1795 * We return zero if we still hold the siglock and should look
1796 * for another signal without checking group_stop_count again.
1798 static inline int handle_group_stop(void)
1802 if (current->signal->group_exit_task == current) {
1804 * Group stop is so we can do a core dump,
1805 * We are the initiating thread, so get on with it.
1807 current->signal->group_exit_task = NULL;
1811 if (current->signal->flags & SIGNAL_GROUP_EXIT)
1813 * Group stop is so another thread can do a core dump,
1814 * or else we are racing against a death signal.
1815 * Just punt the stop so we can get the next signal.
1820 * There is a group stop in progress. We stop
1821 * without any associated signal being in our queue.
1823 stop_count = --current->signal->group_stop_count;
1824 if (stop_count == 0)
1825 current->signal->flags = SIGNAL_STOP_STOPPED;
1826 current->exit_code = current->signal->group_exit_code;
1827 set_current_state(TASK_STOPPED);
1828 spin_unlock_irq(¤t->sighand->siglock);
1829 finish_stop(stop_count);
1833 int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
1834 struct pt_regs *regs, void *cookie)
1836 sigset_t *mask = ¤t->blocked;
1840 spin_lock_irq(¤t->sighand->siglock);
1842 struct k_sigaction *ka;
1844 if (unlikely(current->signal->group_stop_count > 0) &&
1845 handle_group_stop())
1848 signr = dequeue_signal(current, mask, info);
1851 break; /* will return 0 */
1853 if ((current->ptrace & PT_PTRACED) && signr != SIGKILL) {
1854 ptrace_signal_deliver(regs, cookie);
1856 /* Let the debugger run. */
1857 ptrace_stop(signr, signr, info);
1859 /* We're back. Did the debugger cancel the sig? */
1860 signr = current->exit_code;
1864 current->exit_code = 0;
1866 /* Update the siginfo structure if the signal has
1867 changed. If the debugger wanted something
1868 specific in the siginfo structure then it should
1869 have updated *info via PTRACE_SETSIGINFO. */
1870 if (signr != info->si_signo) {
1871 info->si_signo = signr;
1873 info->si_code = SI_USER;
1874 info->si_pid = current->parent->pid;
1875 info->si_uid = current->parent->uid;
1878 /* If the (new) signal is now blocked, requeue it. */
1879 if (sigismember(¤t->blocked, signr)) {
1880 specific_send_sig_info(signr, info, current);
1885 ka = ¤t->sighand->action[signr-1];
1886 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
1888 if (ka->sa.sa_handler != SIG_DFL) {
1889 /* Run the handler. */
1892 if (ka->sa.sa_flags & SA_ONESHOT)
1893 ka->sa.sa_handler = SIG_DFL;
1895 break; /* will return non-zero "signr" value */
1899 * Now we are doing the default action for this signal.
1901 if (sig_kernel_ignore(signr)) /* Default is nothing. */
1904 /* Init gets no signals it doesn't want. */
1905 if (current->pid == 1)
1908 if (sig_kernel_stop(signr)) {
1910 * The default action is to stop all threads in
1911 * the thread group. The job control signals
1912 * do nothing in an orphaned pgrp, but SIGSTOP
1913 * always works. Note that siglock needs to be
1914 * dropped during the call to is_orphaned_pgrp()
1915 * because of lock ordering with tasklist_lock.
1916 * This allows an intervening SIGCONT to be posted.
1917 * We need to check for that and bail out if necessary.
1919 if (signr != SIGSTOP) {
1920 spin_unlock_irq(¤t->sighand->siglock);
1922 /* signals can be posted during this window */
1924 if (is_orphaned_pgrp(process_group(current)))
1927 spin_lock_irq(¤t->sighand->siglock);
1930 if (likely(do_signal_stop(signr))) {
1931 /* It released the siglock. */
1936 * We didn't actually stop, due to a race
1937 * with SIGCONT or something like that.
1942 spin_unlock_irq(¤t->sighand->siglock);
1945 * Anything else is fatal, maybe with a core dump.
1947 current->flags |= PF_SIGNALED;
1948 if (sig_kernel_coredump(signr)) {
1950 * If it was able to dump core, this kills all
1951 * other threads in the group and synchronizes with
1952 * their demise. If we lost the race with another
1953 * thread getting here, it set group_exit_code
1954 * first and our do_group_exit call below will use
1955 * that value and ignore the one we pass it.
1957 do_coredump((long)signr, signr, regs);
1961 * Death signals, no core dump.
1963 do_group_exit(signr);
1966 spin_unlock_irq(¤t->sighand->siglock);
1970 EXPORT_SYMBOL(recalc_sigpending);
1971 EXPORT_SYMBOL_GPL(dequeue_signal);
1972 EXPORT_SYMBOL(flush_signals);
1973 EXPORT_SYMBOL(force_sig);
1974 EXPORT_SYMBOL(kill_pg);
1975 EXPORT_SYMBOL(kill_proc);
1976 EXPORT_SYMBOL(ptrace_notify);
1977 EXPORT_SYMBOL(send_sig);
1978 EXPORT_SYMBOL(send_sig_info);
1979 EXPORT_SYMBOL(sigprocmask);
1980 EXPORT_SYMBOL(block_all_signals);
1981 EXPORT_SYMBOL(unblock_all_signals);
1985 * System call entry points.
1988 asmlinkage long sys_restart_syscall(void)
1990 struct restart_block *restart = ¤t_thread_info()->restart_block;
1991 return restart->fn(restart);
1994 long do_no_restart_syscall(struct restart_block *param)
2000 * We don't need to get the kernel lock - this is all local to this
2001 * particular thread.. (and that's good, because this is _heavily_
2002 * used by various programs)
2006 * This is also useful for kernel threads that want to temporarily
2007 * (or permanently) block certain signals.
2009 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2010 * interface happily blocks "unblockable" signals like SIGKILL
2013 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2018 spin_lock_irq(¤t->sighand->siglock);
2019 old_block = current->blocked;
2023 sigorsets(¤t->blocked, ¤t->blocked, set);
2026 signandsets(¤t->blocked, ¤t->blocked, set);
2029 current->blocked = *set;
2034 recalc_sigpending();
2035 spin_unlock_irq(¤t->sighand->siglock);
2037 *oldset = old_block;
2042 sys_rt_sigprocmask(int how, sigset_t __user *set, sigset_t __user *oset, size_t sigsetsize)
2044 int error = -EINVAL;
2045 sigset_t old_set, new_set;
2047 /* XXX: Don't preclude handling different sized sigset_t's. */
2048 if (sigsetsize != sizeof(sigset_t))
2053 if (copy_from_user(&new_set, set, sizeof(*set)))
2055 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2057 error = sigprocmask(how, &new_set, &old_set);
2063 spin_lock_irq(¤t->sighand->siglock);
2064 old_set = current->blocked;
2065 spin_unlock_irq(¤t->sighand->siglock);
2069 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2077 long do_sigpending(void __user *set, unsigned long sigsetsize)
2079 long error = -EINVAL;
2082 if (sigsetsize > sizeof(sigset_t))
2085 spin_lock_irq(¤t->sighand->siglock);
2086 sigorsets(&pending, ¤t->pending.signal,
2087 ¤t->signal->shared_pending.signal);
2088 spin_unlock_irq(¤t->sighand->siglock);
2090 /* Outside the lock because only this thread touches it. */
2091 sigandsets(&pending, ¤t->blocked, &pending);
2094 if (!copy_to_user(set, &pending, sigsetsize))
2102 sys_rt_sigpending(sigset_t __user *set, size_t sigsetsize)
2104 return do_sigpending(set, sigsetsize);
2107 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2109 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2113 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2115 if (from->si_code < 0)
2116 return __copy_to_user(to, from, sizeof(siginfo_t))
2119 * If you change siginfo_t structure, please be sure
2120 * this code is fixed accordingly.
2121 * It should never copy any pad contained in the structure
2122 * to avoid security leaks, but must copy the generic
2123 * 3 ints plus the relevant union member.
2125 err = __put_user(from->si_signo, &to->si_signo);
2126 err |= __put_user(from->si_errno, &to->si_errno);
2127 err |= __put_user((short)from->si_code, &to->si_code);
2128 switch (from->si_code & __SI_MASK) {
2130 err |= __put_user(from->si_pid, &to->si_pid);
2131 err |= __put_user(from->si_uid, &to->si_uid);
2134 err |= __put_user(from->si_tid, &to->si_tid);
2135 err |= __put_user(from->si_overrun, &to->si_overrun);
2136 err |= __put_user(from->si_ptr, &to->si_ptr);
2139 err |= __put_user(from->si_band, &to->si_band);
2140 err |= __put_user(from->si_fd, &to->si_fd);
2143 err |= __put_user(from->si_addr, &to->si_addr);
2144 #ifdef __ARCH_SI_TRAPNO
2145 err |= __put_user(from->si_trapno, &to->si_trapno);
2149 err |= __put_user(from->si_pid, &to->si_pid);
2150 err |= __put_user(from->si_uid, &to->si_uid);
2151 err |= __put_user(from->si_status, &to->si_status);
2152 err |= __put_user(from->si_utime, &to->si_utime);
2153 err |= __put_user(from->si_stime, &to->si_stime);
2155 case __SI_RT: /* This is not generated by the kernel as of now. */
2156 case __SI_MESGQ: /* But this is */
2157 err |= __put_user(from->si_pid, &to->si_pid);
2158 err |= __put_user(from->si_uid, &to->si_uid);
2159 err |= __put_user(from->si_ptr, &to->si_ptr);
2161 default: /* this is just in case for now ... */
2162 err |= __put_user(from->si_pid, &to->si_pid);
2163 err |= __put_user(from->si_uid, &to->si_uid);
2172 sys_rt_sigtimedwait(const sigset_t __user *uthese,
2173 siginfo_t __user *uinfo,
2174 const struct timespec __user *uts,
2183 /* XXX: Don't preclude handling different sized sigset_t's. */
2184 if (sigsetsize != sizeof(sigset_t))
2187 if (copy_from_user(&these, uthese, sizeof(these)))
2191 * Invert the set of allowed signals to get those we
2194 sigdelsetmask(&these, sigmask(SIGKILL)|sigmask(SIGSTOP));
2198 if (copy_from_user(&ts, uts, sizeof(ts)))
2200 if (ts.tv_nsec >= 1000000000L || ts.tv_nsec < 0
2205 spin_lock_irq(¤t->sighand->siglock);
2206 sig = dequeue_signal(current, &these, &info);
2208 timeout = MAX_SCHEDULE_TIMEOUT;
2210 timeout = (timespec_to_jiffies(&ts)
2211 + (ts.tv_sec || ts.tv_nsec));
2214 /* None ready -- temporarily unblock those we're
2215 * interested while we are sleeping in so that we'll
2216 * be awakened when they arrive. */
2217 current->real_blocked = current->blocked;
2218 sigandsets(¤t->blocked, ¤t->blocked, &these);
2219 recalc_sigpending();
2220 spin_unlock_irq(¤t->sighand->siglock);
2222 current->state = TASK_INTERRUPTIBLE;
2223 timeout = schedule_timeout(timeout);
2226 spin_lock_irq(¤t->sighand->siglock);
2227 sig = dequeue_signal(current, &these, &info);
2228 current->blocked = current->real_blocked;
2229 siginitset(¤t->real_blocked, 0);
2230 recalc_sigpending();
2233 spin_unlock_irq(¤t->sighand->siglock);
2238 if (copy_siginfo_to_user(uinfo, &info))
2251 sys_kill(int pid, int sig)
2253 struct siginfo info;
2255 info.si_signo = sig;
2257 info.si_code = SI_USER;
2258 info.si_pid = current->tgid;
2259 info.si_uid = current->uid;
2261 return kill_something_info(sig, &info, pid);
2265 * sys_tgkill - send signal to one specific thread
2266 * @tgid: the thread group ID of the thread
2267 * @pid: the PID of the thread
2268 * @sig: signal to be sent
2270 * This syscall also checks the tgid and returns -ESRCH even if the PID
2271 * exists but it's not belonging to the target process anymore. This
2272 * method solves the problem of threads exiting and PIDs getting reused.
2274 asmlinkage long sys_tgkill(int tgid, int pid, int sig)
2276 struct siginfo info;
2278 struct task_struct *p;
2280 /* This is only valid for single tasks */
2281 if (pid <= 0 || tgid <= 0)
2284 info.si_signo = sig;
2286 info.si_code = SI_TKILL;
2287 info.si_pid = current->tgid;
2288 info.si_uid = current->uid;
2290 read_lock(&tasklist_lock);
2291 p = find_task_by_pid(pid);
2293 if (p && (p->tgid == tgid)) {
2294 error = check_kill_permission(sig, &info, p);
2296 * The null signal is a permissions and process existence
2297 * probe. No signal is actually delivered.
2299 if (!error && sig && p->sighand) {
2300 spin_lock_irq(&p->sighand->siglock);
2301 handle_stop_signal(sig, p);
2302 error = specific_send_sig_info(sig, &info, p);
2303 spin_unlock_irq(&p->sighand->siglock);
2306 read_unlock(&tasklist_lock);
2311 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2314 sys_tkill(int pid, int sig)
2316 struct siginfo info;
2318 struct task_struct *p;
2320 /* This is only valid for single tasks */
2324 info.si_signo = sig;
2326 info.si_code = SI_TKILL;
2327 info.si_pid = current->tgid;
2328 info.si_uid = current->uid;
2330 read_lock(&tasklist_lock);
2331 p = find_task_by_pid(pid);
2334 error = check_kill_permission(sig, &info, p);
2336 * The null signal is a permissions and process existence
2337 * probe. No signal is actually delivered.
2339 if (!error && sig && p->sighand) {
2340 spin_lock_irq(&p->sighand->siglock);
2341 handle_stop_signal(sig, p);
2342 error = specific_send_sig_info(sig, &info, p);
2343 spin_unlock_irq(&p->sighand->siglock);
2346 read_unlock(&tasklist_lock);
2351 sys_rt_sigqueueinfo(int pid, int sig, siginfo_t __user *uinfo)
2355 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2358 /* Not even root can pretend to send signals from the kernel.
2359 Nor can they impersonate a kill(), which adds source info. */
2360 if (info.si_code >= 0)
2362 info.si_signo = sig;
2364 /* POSIX.1b doesn't mention process groups. */
2365 return kill_proc_info(sig, &info, pid);
2369 do_sigaction(int sig, const struct k_sigaction *act, struct k_sigaction *oact)
2371 struct k_sigaction *k;
2373 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
2376 k = ¤t->sighand->action[sig-1];
2378 spin_lock_irq(¤t->sighand->siglock);
2379 if (signal_pending(current)) {
2381 * If there might be a fatal signal pending on multiple
2382 * threads, make sure we take it before changing the action.
2384 spin_unlock_irq(¤t->sighand->siglock);
2385 return -ERESTARTNOINTR;
2394 * "Setting a signal action to SIG_IGN for a signal that is
2395 * pending shall cause the pending signal to be discarded,
2396 * whether or not it is blocked."
2398 * "Setting a signal action to SIG_DFL for a signal that is
2399 * pending and whose default action is to ignore the signal
2400 * (for example, SIGCHLD), shall cause the pending signal to
2401 * be discarded, whether or not it is blocked"
2403 if (act->sa.sa_handler == SIG_IGN ||
2404 (act->sa.sa_handler == SIG_DFL &&
2405 sig_kernel_ignore(sig))) {
2407 * This is a fairly rare case, so we only take the
2408 * tasklist_lock once we're sure we'll need it.
2409 * Now we must do this little unlock and relock
2410 * dance to maintain the lock hierarchy.
2412 struct task_struct *t = current;
2413 spin_unlock_irq(&t->sighand->siglock);
2414 read_lock(&tasklist_lock);
2415 spin_lock_irq(&t->sighand->siglock);
2417 sigdelsetmask(&k->sa.sa_mask,
2418 sigmask(SIGKILL) | sigmask(SIGSTOP));
2419 rm_from_queue(sigmask(sig), &t->signal->shared_pending);
2421 rm_from_queue(sigmask(sig), &t->pending);
2422 recalc_sigpending_tsk(t);
2424 } while (t != current);
2425 spin_unlock_irq(¤t->sighand->siglock);
2426 read_unlock(&tasklist_lock);
2431 sigdelsetmask(&k->sa.sa_mask,
2432 sigmask(SIGKILL) | sigmask(SIGSTOP));
2435 spin_unlock_irq(¤t->sighand->siglock);
2440 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
2446 oss.ss_sp = (void __user *) current->sas_ss_sp;
2447 oss.ss_size = current->sas_ss_size;
2448 oss.ss_flags = sas_ss_flags(sp);
2457 if (!access_ok(VERIFY_READ, uss, sizeof(*uss))
2458 || __get_user(ss_sp, &uss->ss_sp)
2459 || __get_user(ss_flags, &uss->ss_flags)
2460 || __get_user(ss_size, &uss->ss_size))
2464 if (on_sig_stack(sp))
2470 * Note - this code used to test ss_flags incorrectly
2471 * old code may have been written using ss_flags==0
2472 * to mean ss_flags==SS_ONSTACK (as this was the only
2473 * way that worked) - this fix preserves that older
2476 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
2479 if (ss_flags == SS_DISABLE) {
2484 if (ss_size < MINSIGSTKSZ)
2488 current->sas_ss_sp = (unsigned long) ss_sp;
2489 current->sas_ss_size = ss_size;
2494 if (copy_to_user(uoss, &oss, sizeof(oss)))
2503 #ifdef __ARCH_WANT_SYS_SIGPENDING
2506 sys_sigpending(old_sigset_t __user *set)
2508 return do_sigpending(set, sizeof(*set));
2513 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
2514 /* Some platforms have their own version with special arguments others
2515 support only sys_rt_sigprocmask. */
2518 sys_sigprocmask(int how, old_sigset_t __user *set, old_sigset_t __user *oset)
2521 old_sigset_t old_set, new_set;
2525 if (copy_from_user(&new_set, set, sizeof(*set)))
2527 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
2529 spin_lock_irq(¤t->sighand->siglock);
2530 old_set = current->blocked.sig[0];
2538 sigaddsetmask(¤t->blocked, new_set);
2541 sigdelsetmask(¤t->blocked, new_set);
2544 current->blocked.sig[0] = new_set;
2548 recalc_sigpending();
2549 spin_unlock_irq(¤t->sighand->siglock);
2555 old_set = current->blocked.sig[0];
2558 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2565 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
2567 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
2569 sys_rt_sigaction(int sig,
2570 const struct sigaction __user *act,
2571 struct sigaction __user *oact,
2574 struct k_sigaction new_sa, old_sa;
2577 /* XXX: Don't preclude handling different sized sigset_t's. */
2578 if (sigsetsize != sizeof(sigset_t))
2582 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
2586 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
2589 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
2595 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
2597 #ifdef __ARCH_WANT_SYS_SGETMASK
2600 * For backwards compatibility. Functionality superseded by sigprocmask.
2606 return current->blocked.sig[0];
2610 sys_ssetmask(int newmask)
2614 spin_lock_irq(¤t->sighand->siglock);
2615 old = current->blocked.sig[0];
2617 siginitset(¤t->blocked, newmask & ~(sigmask(SIGKILL)|
2619 recalc_sigpending();
2620 spin_unlock_irq(¤t->sighand->siglock);
2624 #endif /* __ARCH_WANT_SGETMASK */
2626 #ifdef __ARCH_WANT_SYS_SIGNAL
2628 * For backwards compatibility. Functionality superseded by sigaction.
2630 asmlinkage unsigned long
2631 sys_signal(int sig, __sighandler_t handler)
2633 struct k_sigaction new_sa, old_sa;
2636 new_sa.sa.sa_handler = handler;
2637 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
2639 ret = do_sigaction(sig, &new_sa, &old_sa);
2641 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
2643 #endif /* __ARCH_WANT_SYS_SIGNAL */
2645 #ifdef __ARCH_WANT_SYS_PAUSE
2650 current->state = TASK_INTERRUPTIBLE;
2652 return -ERESTARTNOHAND;
2657 void __init signals_init(void)
2660 kmem_cache_create("sigqueue",
2661 sizeof(struct sigqueue),
2662 __alignof__(struct sigqueue),
2663 SLAB_PANIC, NULL, NULL);