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 <asm/param.h>
26 #include <asm/uaccess.h>
27 #include <asm/unistd.h>
28 #include <asm/siginfo.h>
30 extern void k_getrusage(struct task_struct *, int, struct rusage *);
33 * SLAB caches for signal bits.
36 static kmem_cache_t *sigqueue_cachep;
39 * In POSIX a signal is sent either to a specific thread (Linux task)
40 * or to the process as a whole (Linux thread group). How the signal
41 * is sent determines whether it's to one thread or the whole group,
42 * which determines which signal mask(s) are involved in blocking it
43 * from being delivered until later. When the signal is delivered,
44 * either it's caught or ignored by a user handler or it has a default
45 * effect that applies to the whole thread group (POSIX process).
47 * The possible effects an unblocked signal set to SIG_DFL can have are:
48 * ignore - Nothing Happens
49 * terminate - kill the process, i.e. all threads in the group,
50 * similar to exit_group. The group leader (only) reports
51 * WIFSIGNALED status to its parent.
52 * coredump - write a core dump file describing all threads using
53 * the same mm and then kill all those threads
54 * stop - stop all the threads in the group, i.e. TASK_STOPPED state
56 * SIGKILL and SIGSTOP cannot be caught, blocked, or ignored.
57 * Other signals when not blocked and set to SIG_DFL behaves as follows.
58 * The job control signals also have other special effects.
60 * +--------------------+------------------+
61 * | POSIX signal | default action |
62 * +--------------------+------------------+
63 * | SIGHUP | terminate |
64 * | SIGINT | terminate |
65 * | SIGQUIT | coredump |
66 * | SIGILL | coredump |
67 * | SIGTRAP | coredump |
68 * | SIGABRT/SIGIOT | coredump |
69 * | SIGBUS | coredump |
70 * | SIGFPE | coredump |
71 * | SIGKILL | terminate(+) |
72 * | SIGUSR1 | terminate |
73 * | SIGSEGV | coredump |
74 * | SIGUSR2 | terminate |
75 * | SIGPIPE | terminate |
76 * | SIGALRM | terminate |
77 * | SIGTERM | terminate |
78 * | SIGCHLD | ignore |
79 * | SIGCONT | ignore(*) |
80 * | SIGSTOP | stop(*)(+) |
81 * | SIGTSTP | stop(*) |
82 * | SIGTTIN | stop(*) |
83 * | SIGTTOU | stop(*) |
85 * | SIGXCPU | coredump |
86 * | SIGXFSZ | coredump |
87 * | SIGVTALRM | terminate |
88 * | SIGPROF | terminate |
89 * | SIGPOLL/SIGIO | terminate |
90 * | SIGSYS/SIGUNUSED | coredump |
91 * | SIGSTKFLT | terminate |
92 * | SIGWINCH | ignore |
93 * | SIGPWR | terminate |
94 * | SIGRTMIN-SIGRTMAX | terminate |
95 * +--------------------+------------------+
96 * | non-POSIX signal | default action |
97 * +--------------------+------------------+
98 * | SIGEMT | coredump |
99 * +--------------------+------------------+
101 * (+) For SIGKILL and SIGSTOP the action is "always", not just "default".
102 * (*) Special job control effects:
103 * When SIGCONT is sent, it resumes the process (all threads in the group)
104 * from TASK_STOPPED state and also clears any pending/queued stop signals
105 * (any of those marked with "stop(*)"). This happens regardless of blocking,
106 * catching, or ignoring SIGCONT. When any stop signal is sent, it clears
107 * any pending/queued SIGCONT signals; this happens regardless of blocking,
108 * catching, or ignored the stop signal, though (except for SIGSTOP) the
109 * default action of stopping the process may happen later or never.
113 #define M_SIGEMT M(SIGEMT)
118 #if SIGRTMIN > BITS_PER_LONG
119 #define M(sig) (1ULL << ((sig)-1))
121 #define M(sig) (1UL << ((sig)-1))
123 #define T(sig, mask) (M(sig) & (mask))
125 #define SIG_KERNEL_ONLY_MASK (\
126 M(SIGKILL) | M(SIGSTOP) )
128 #define SIG_KERNEL_STOP_MASK (\
129 M(SIGSTOP) | M(SIGTSTP) | M(SIGTTIN) | M(SIGTTOU) )
131 #define SIG_KERNEL_COREDUMP_MASK (\
132 M(SIGQUIT) | M(SIGILL) | M(SIGTRAP) | M(SIGABRT) | \
133 M(SIGFPE) | M(SIGSEGV) | M(SIGBUS) | M(SIGSYS) | \
134 M(SIGXCPU) | M(SIGXFSZ) | M_SIGEMT )
136 #define SIG_KERNEL_IGNORE_MASK (\
137 M(SIGCONT) | M(SIGCHLD) | M(SIGWINCH) | M(SIGURG) )
139 #define sig_kernel_only(sig) \
140 (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_ONLY_MASK))
141 #define sig_kernel_coredump(sig) \
142 (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_COREDUMP_MASK))
143 #define sig_kernel_ignore(sig) \
144 (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_IGNORE_MASK))
145 #define sig_kernel_stop(sig) \
146 (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_STOP_MASK))
148 #define sig_user_defined(t, signr) \
149 (((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_DFL) && \
150 ((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_IGN))
152 #define sig_fatal(t, signr) \
153 (!T(signr, SIG_KERNEL_IGNORE_MASK|SIG_KERNEL_STOP_MASK) && \
154 (t)->sighand->action[(signr)-1].sa.sa_handler == SIG_DFL)
156 static int sig_ignored(struct task_struct *t, int sig)
158 void __user * handler;
161 * Tracers always want to know about signals..
163 if (t->ptrace & PT_PTRACED)
167 * Blocked signals are never ignored, since the
168 * signal handler may change by the time it is
171 if (sigismember(&t->blocked, sig))
174 /* Is it explicitly or implicitly ignored? */
175 handler = t->sighand->action[sig-1].sa.sa_handler;
176 return handler == SIG_IGN ||
177 (handler == SIG_DFL && sig_kernel_ignore(sig));
181 * Re-calculate pending state from the set of locally pending
182 * signals, globally pending signals, and blocked signals.
184 static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
189 switch (_NSIG_WORDS) {
191 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
192 ready |= signal->sig[i] &~ blocked->sig[i];
195 case 4: ready = signal->sig[3] &~ blocked->sig[3];
196 ready |= signal->sig[2] &~ blocked->sig[2];
197 ready |= signal->sig[1] &~ blocked->sig[1];
198 ready |= signal->sig[0] &~ blocked->sig[0];
201 case 2: ready = signal->sig[1] &~ blocked->sig[1];
202 ready |= signal->sig[0] &~ blocked->sig[0];
205 case 1: ready = signal->sig[0] &~ blocked->sig[0];
210 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
212 fastcall void recalc_sigpending_tsk(struct task_struct *t)
214 if (t->signal->group_stop_count > 0 ||
215 PENDING(&t->pending, &t->blocked) ||
216 PENDING(&t->signal->shared_pending, &t->blocked))
217 set_tsk_thread_flag(t, TIF_SIGPENDING);
219 clear_tsk_thread_flag(t, TIF_SIGPENDING);
222 void recalc_sigpending(void)
224 recalc_sigpending_tsk(current);
227 /* Given the mask, find the first available signal that should be serviced. */
230 next_signal(struct sigpending *pending, sigset_t *mask)
232 unsigned long i, *s, *m, x;
235 s = pending->signal.sig;
237 switch (_NSIG_WORDS) {
239 for (i = 0; i < _NSIG_WORDS; ++i, ++s, ++m)
240 if ((x = *s &~ *m) != 0) {
241 sig = ffz(~x) + i*_NSIG_BPW + 1;
246 case 2: if ((x = s[0] &~ m[0]) != 0)
248 else if ((x = s[1] &~ m[1]) != 0)
255 case 1: if ((x = *s &~ *m) != 0)
263 static struct sigqueue *__sigqueue_alloc(struct task_struct *t, int flags)
265 struct sigqueue *q = NULL;
267 if (atomic_read(&t->user->sigpending) <
268 t->signal->rlim[RLIMIT_SIGPENDING].rlim_cur)
269 q = kmem_cache_alloc(sigqueue_cachep, flags);
271 INIT_LIST_HEAD(&q->list);
274 q->user = get_uid(t->user);
275 atomic_inc(&q->user->sigpending);
280 static inline void __sigqueue_free(struct sigqueue *q)
282 if (q->flags & SIGQUEUE_PREALLOC)
284 atomic_dec(&q->user->sigpending);
286 kmem_cache_free(sigqueue_cachep, q);
289 static void flush_sigqueue(struct sigpending *queue)
293 sigemptyset(&queue->signal);
294 while (!list_empty(&queue->list)) {
295 q = list_entry(queue->list.next, struct sigqueue , list);
296 list_del_init(&q->list);
302 * Flush all pending signals for a task.
306 flush_signals(struct task_struct *t)
310 spin_lock_irqsave(&t->sighand->siglock, flags);
311 clear_tsk_thread_flag(t,TIF_SIGPENDING);
312 flush_sigqueue(&t->pending);
313 flush_sigqueue(&t->signal->shared_pending);
314 spin_unlock_irqrestore(&t->sighand->siglock, flags);
318 * This function expects the tasklist_lock write-locked.
320 void __exit_sighand(struct task_struct *tsk)
322 struct sighand_struct * sighand = tsk->sighand;
324 /* Ok, we're done with the signal handlers */
326 if (atomic_dec_and_test(&sighand->count))
327 kmem_cache_free(sighand_cachep, sighand);
330 void exit_sighand(struct task_struct *tsk)
332 write_lock_irq(&tasklist_lock);
334 write_unlock_irq(&tasklist_lock);
338 * This function expects the tasklist_lock write-locked.
340 void __exit_signal(struct task_struct *tsk)
342 struct signal_struct * sig = tsk->signal;
343 struct sighand_struct * sighand = tsk->sighand;
347 if (!atomic_read(&sig->count))
349 spin_lock(&sighand->siglock);
350 if (atomic_dec_and_test(&sig->count)) {
351 if (tsk == sig->curr_target)
352 sig->curr_target = next_thread(tsk);
354 spin_unlock(&sighand->siglock);
355 flush_sigqueue(&sig->shared_pending);
358 * If there is any task waiting for the group exit
361 if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count) {
362 wake_up_process(sig->group_exit_task);
363 sig->group_exit_task = NULL;
365 if (tsk == sig->curr_target)
366 sig->curr_target = next_thread(tsk);
369 * Accumulate here the counters for all threads but the
370 * group leader as they die, so they can be added into
371 * the process-wide totals when those are taken.
372 * The group leader stays around as a zombie as long
373 * as there are other threads. When it gets reaped,
374 * the exit.c code will add its counts into these totals.
375 * We won't ever get here for the group leader, since it
376 * will have been the last reference on the signal_struct.
378 sig->utime = cputime_add(sig->utime, tsk->utime);
379 sig->stime = cputime_add(sig->stime, tsk->stime);
380 sig->min_flt += tsk->min_flt;
381 sig->maj_flt += tsk->maj_flt;
382 sig->nvcsw += tsk->nvcsw;
383 sig->nivcsw += tsk->nivcsw;
384 spin_unlock(&sighand->siglock);
385 sig = NULL; /* Marker for below. */
387 clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
388 flush_sigqueue(&tsk->pending);
391 * We are cleaning up the signal_struct here. We delayed
392 * calling exit_itimers until after flush_sigqueue, just in
393 * case our thread-local pending queue contained a queued
394 * timer signal that would have been cleared in
395 * exit_itimers. When that called sigqueue_free, it would
396 * attempt to re-take the tasklist_lock and deadlock. This
397 * can never happen if we ensure that all queues the
398 * timer's signal might be queued on have been flushed
399 * first. The shared_pending queue, and our own pending
400 * queue are the only queues the timer could be on, since
401 * there are no other threads left in the group and timer
402 * signals are constrained to threads inside the group.
405 kmem_cache_free(signal_cachep, sig);
409 void exit_signal(struct task_struct *tsk)
411 write_lock_irq(&tasklist_lock);
413 write_unlock_irq(&tasklist_lock);
417 * Flush all handlers for a task.
421 flush_signal_handlers(struct task_struct *t, int force_default)
424 struct k_sigaction *ka = &t->sighand->action[0];
425 for (i = _NSIG ; i != 0 ; i--) {
426 if (force_default || ka->sa.sa_handler != SIG_IGN)
427 ka->sa.sa_handler = SIG_DFL;
429 sigemptyset(&ka->sa.sa_mask);
435 /* Notify the system that a driver wants to block all signals for this
436 * process, and wants to be notified if any signals at all were to be
437 * sent/acted upon. If the notifier routine returns non-zero, then the
438 * signal will be acted upon after all. If the notifier routine returns 0,
439 * then then signal will be blocked. Only one block per process is
440 * allowed. priv is a pointer to private data that the notifier routine
441 * can use to determine if the signal should be blocked or not. */
444 block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
448 spin_lock_irqsave(¤t->sighand->siglock, flags);
449 current->notifier_mask = mask;
450 current->notifier_data = priv;
451 current->notifier = notifier;
452 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
455 /* Notify the system that blocking has ended. */
458 unblock_all_signals(void)
462 spin_lock_irqsave(¤t->sighand->siglock, flags);
463 current->notifier = NULL;
464 current->notifier_data = NULL;
466 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
469 static inline int collect_signal(int sig, struct sigpending *list, siginfo_t *info)
471 struct sigqueue *q, *first = NULL;
472 int still_pending = 0;
474 if (unlikely(!sigismember(&list->signal, sig)))
478 * Collect the siginfo appropriate to this signal. Check if
479 * there is another siginfo for the same signal.
481 list_for_each_entry(q, &list->list, list) {
482 if (q->info.si_signo == sig) {
491 list_del_init(&first->list);
492 copy_siginfo(info, &first->info);
493 __sigqueue_free(first);
495 sigdelset(&list->signal, sig);
498 /* Ok, it wasn't in the queue. This must be
499 a fast-pathed signal or we must have been
500 out of queue space. So zero out the info.
502 sigdelset(&list->signal, sig);
503 info->si_signo = sig;
512 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
517 sig = next_signal(pending, mask);
519 if (current->notifier) {
520 if (sigismember(current->notifier_mask, sig)) {
521 if (!(current->notifier)(current->notifier_data)) {
522 clear_thread_flag(TIF_SIGPENDING);
528 if (!collect_signal(sig, pending, info))
538 * Dequeue a signal and return the element to the caller, which is
539 * expected to free it.
541 * All callers have to hold the siglock.
543 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
545 int signr = __dequeue_signal(&tsk->pending, mask, info);
547 signr = __dequeue_signal(&tsk->signal->shared_pending,
549 if (signr && unlikely(sig_kernel_stop(signr))) {
551 * Set a marker that we have dequeued a stop signal. Our
552 * caller might release the siglock and then the pending
553 * stop signal it is about to process is no longer in the
554 * pending bitmasks, but must still be cleared by a SIGCONT
555 * (and overruled by a SIGKILL). So those cases clear this
556 * shared flag after we've set it. Note that this flag may
557 * remain set after the signal we return is ignored or
558 * handled. That doesn't matter because its only purpose
559 * is to alert stop-signal processing code when another
560 * processor has come along and cleared the flag.
562 tsk->signal->flags |= SIGNAL_STOP_DEQUEUED;
565 ((info->si_code & __SI_MASK) == __SI_TIMER) &&
566 info->si_sys_private){
567 do_schedule_next_timer(info);
573 * Tell a process that it has a new active signal..
575 * NOTE! we rely on the previous spin_lock to
576 * lock interrupts for us! We can only be called with
577 * "siglock" held, and the local interrupt must
578 * have been disabled when that got acquired!
580 * No need to set need_resched since signal event passing
581 * goes through ->blocked
583 void signal_wake_up(struct task_struct *t, int resume)
587 set_tsk_thread_flag(t, TIF_SIGPENDING);
590 * For SIGKILL, we want to wake it up in the stopped/traced case.
591 * We don't check t->state here because there is a race with it
592 * executing another processor and just now entering stopped state.
593 * By using wake_up_state, we ensure the process will wake up and
594 * handle its death signal.
596 mask = TASK_INTERRUPTIBLE;
598 mask |= TASK_STOPPED | TASK_TRACED;
599 if (!wake_up_state(t, mask))
604 * Remove signals in mask from the pending set and queue.
605 * Returns 1 if any signals were found.
607 * All callers must be holding the siglock.
609 static int rm_from_queue(unsigned long mask, struct sigpending *s)
611 struct sigqueue *q, *n;
613 if (!sigtestsetmask(&s->signal, mask))
616 sigdelsetmask(&s->signal, mask);
617 list_for_each_entry_safe(q, n, &s->list, list) {
618 if (q->info.si_signo < SIGRTMIN &&
619 (mask & sigmask(q->info.si_signo))) {
620 list_del_init(&q->list);
628 * Bad permissions for sending the signal
630 static int check_kill_permission(int sig, struct siginfo *info,
631 struct task_struct *t)
634 if (sig < 0 || sig > _NSIG)
637 if ((!info || ((unsigned long)info != 1 &&
638 (unsigned long)info != 2 && SI_FROMUSER(info)))
639 && ((sig != SIGCONT) ||
640 (current->signal->session != t->signal->session))
641 && (current->euid ^ t->suid) && (current->euid ^ t->uid)
642 && (current->uid ^ t->suid) && (current->uid ^ t->uid)
643 && !capable(CAP_KILL))
645 return security_task_kill(t, info, sig);
649 static void do_notify_parent_cldstop(struct task_struct *tsk,
650 struct task_struct *parent,
654 * Handle magic process-wide effects of stop/continue signals.
655 * Unlike the signal actions, these happen immediately at signal-generation
656 * time regardless of blocking, ignoring, or handling. This does the
657 * actual continuing for SIGCONT, but not the actual stopping for stop
658 * signals. The process stop is done as a signal action for SIG_DFL.
660 static void handle_stop_signal(int sig, struct task_struct *p)
662 struct task_struct *t;
664 if (p->flags & SIGNAL_GROUP_EXIT)
666 * The process is in the middle of dying already.
670 if (sig_kernel_stop(sig)) {
672 * This is a stop signal. Remove SIGCONT from all queues.
674 rm_from_queue(sigmask(SIGCONT), &p->signal->shared_pending);
677 rm_from_queue(sigmask(SIGCONT), &t->pending);
680 } else if (sig == SIGCONT) {
682 * Remove all stop signals from all queues,
683 * and wake all threads.
685 if (unlikely(p->signal->group_stop_count > 0)) {
687 * There was a group stop in progress. We'll
688 * pretend it finished before we got here. We are
689 * obliged to report it to the parent: if the
690 * SIGSTOP happened "after" this SIGCONT, then it
691 * would have cleared this pending SIGCONT. If it
692 * happened "before" this SIGCONT, then the parent
693 * got the SIGCHLD about the stop finishing before
694 * the continue happened. We do the notification
695 * now, and it's as if the stop had finished and
696 * the SIGCHLD was pending on entry to this kill.
698 p->signal->group_stop_count = 0;
699 p->signal->flags = SIGNAL_STOP_CONTINUED;
700 spin_unlock(&p->sighand->siglock);
701 if (p->ptrace & PT_PTRACED)
702 do_notify_parent_cldstop(p, p->parent,
705 do_notify_parent_cldstop(
707 p->group_leader->real_parent,
709 spin_lock(&p->sighand->siglock);
711 rm_from_queue(SIG_KERNEL_STOP_MASK, &p->signal->shared_pending);
715 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
718 * If there is a handler for SIGCONT, we must make
719 * sure that no thread returns to user mode before
720 * we post the signal, in case it was the only
721 * thread eligible to run the signal handler--then
722 * it must not do anything between resuming and
723 * running the handler. With the TIF_SIGPENDING
724 * flag set, the thread will pause and acquire the
725 * siglock that we hold now and until we've queued
726 * the pending signal.
728 * Wake up the stopped thread _after_ setting
731 state = TASK_STOPPED;
732 if (sig_user_defined(t, SIGCONT) && !sigismember(&t->blocked, SIGCONT)) {
733 set_tsk_thread_flag(t, TIF_SIGPENDING);
734 state |= TASK_INTERRUPTIBLE;
736 wake_up_state(t, state);
741 if (p->signal->flags & SIGNAL_STOP_STOPPED) {
743 * We were in fact stopped, and are now continued.
744 * Notify the parent with CLD_CONTINUED.
746 p->signal->flags = SIGNAL_STOP_CONTINUED;
747 p->signal->group_exit_code = 0;
748 spin_unlock(&p->sighand->siglock);
749 if (p->ptrace & PT_PTRACED)
750 do_notify_parent_cldstop(p, p->parent,
753 do_notify_parent_cldstop(
755 p->group_leader->real_parent,
757 spin_lock(&p->sighand->siglock);
760 * We are not stopped, but there could be a stop
761 * signal in the middle of being processed after
762 * being removed from the queue. Clear that too.
764 p->signal->flags = 0;
766 } else if (sig == SIGKILL) {
768 * Make sure that any pending stop signal already dequeued
769 * is undone by the wakeup for SIGKILL.
771 p->signal->flags = 0;
775 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
776 struct sigpending *signals)
778 struct sigqueue * q = NULL;
782 * fast-pathed signals for kernel-internal things like SIGSTOP
785 if ((unsigned long)info == 2)
788 /* Real-time signals must be queued if sent by sigqueue, or
789 some other real-time mechanism. It is implementation
790 defined whether kill() does so. We attempt to do so, on
791 the principle of least surprise, but since kill is not
792 allowed to fail with EAGAIN when low on memory we just
793 make sure at least one signal gets delivered and don't
794 pass on the info struct. */
796 q = __sigqueue_alloc(t, GFP_ATOMIC);
798 list_add_tail(&q->list, &signals->list);
799 switch ((unsigned long) info) {
801 q->info.si_signo = sig;
802 q->info.si_errno = 0;
803 q->info.si_code = SI_USER;
804 q->info.si_pid = current->pid;
805 q->info.si_uid = current->uid;
808 q->info.si_signo = sig;
809 q->info.si_errno = 0;
810 q->info.si_code = SI_KERNEL;
815 copy_siginfo(&q->info, info);
819 if (sig >= SIGRTMIN && info && (unsigned long)info != 1
820 && info->si_code != SI_USER)
822 * Queue overflow, abort. We may abort if the signal was rt
823 * and sent by user using something other than kill().
826 if (((unsigned long)info > 1) && (info->si_code == SI_TIMER))
828 * Set up a return to indicate that we dropped
831 ret = info->si_sys_private;
835 sigaddset(&signals->signal, sig);
839 #define LEGACY_QUEUE(sigptr, sig) \
840 (((sig) < SIGRTMIN) && sigismember(&(sigptr)->signal, (sig)))
844 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
848 if (!irqs_disabled())
850 assert_spin_locked(&t->sighand->siglock);
852 if (((unsigned long)info > 2) && (info->si_code == SI_TIMER))
854 * Set up a return to indicate that we dropped the signal.
856 ret = info->si_sys_private;
858 /* Short-circuit ignored signals. */
859 if (sig_ignored(t, sig))
862 /* Support queueing exactly one non-rt signal, so that we
863 can get more detailed information about the cause of
865 if (LEGACY_QUEUE(&t->pending, sig))
868 ret = send_signal(sig, info, t, &t->pending);
869 if (!ret && !sigismember(&t->blocked, sig))
870 signal_wake_up(t, sig == SIGKILL);
876 * Force a signal that the process can't ignore: if necessary
877 * we unblock the signal and change any SIG_IGN to SIG_DFL.
881 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
883 unsigned long int flags;
886 spin_lock_irqsave(&t->sighand->siglock, flags);
887 if (sigismember(&t->blocked, sig) || t->sighand->action[sig-1].sa.sa_handler == SIG_IGN) {
888 t->sighand->action[sig-1].sa.sa_handler = SIG_DFL;
889 sigdelset(&t->blocked, sig);
890 recalc_sigpending_tsk(t);
892 ret = specific_send_sig_info(sig, info, t);
893 spin_unlock_irqrestore(&t->sighand->siglock, flags);
899 force_sig_specific(int sig, struct task_struct *t)
901 unsigned long int flags;
903 spin_lock_irqsave(&t->sighand->siglock, flags);
904 if (t->sighand->action[sig-1].sa.sa_handler == SIG_IGN)
905 t->sighand->action[sig-1].sa.sa_handler = SIG_DFL;
906 sigdelset(&t->blocked, sig);
907 recalc_sigpending_tsk(t);
908 specific_send_sig_info(sig, (void *)2, t);
909 spin_unlock_irqrestore(&t->sighand->siglock, flags);
913 * Test if P wants to take SIG. After we've checked all threads with this,
914 * it's equivalent to finding no threads not blocking SIG. Any threads not
915 * blocking SIG were ruled out because they are not running and already
916 * have pending signals. Such threads will dequeue from the shared queue
917 * as soon as they're available, so putting the signal on the shared queue
918 * will be equivalent to sending it to one such thread.
920 #define wants_signal(sig, p, mask) \
921 (!sigismember(&(p)->blocked, sig) \
922 && !((p)->state & mask) \
923 && !((p)->flags & PF_EXITING) \
924 && (task_curr(p) || !signal_pending(p)))
928 __group_complete_signal(int sig, struct task_struct *p)
931 struct task_struct *t;
934 * Don't bother traced and stopped tasks (but
935 * SIGKILL will punch through that).
937 mask = TASK_STOPPED | TASK_TRACED;
942 * Now find a thread we can wake up to take the signal off the queue.
944 * If the main thread wants the signal, it gets first crack.
945 * Probably the least surprising to the average bear.
947 if (wants_signal(sig, p, mask))
949 else if (thread_group_empty(p))
951 * There is just one thread and it does not need to be woken.
952 * It will dequeue unblocked signals before it runs again.
957 * Otherwise try to find a suitable thread.
959 t = p->signal->curr_target;
961 /* restart balancing at this thread */
962 t = p->signal->curr_target = p;
963 BUG_ON(t->tgid != p->tgid);
965 while (!wants_signal(sig, t, mask)) {
967 if (t == p->signal->curr_target)
969 * No thread needs to be woken.
970 * Any eligible threads will see
971 * the signal in the queue soon.
975 p->signal->curr_target = t;
979 * Found a killable thread. If the signal will be fatal,
980 * then start taking the whole group down immediately.
982 if (sig_fatal(p, sig) && !(p->signal->flags & SIGNAL_GROUP_EXIT) &&
983 !sigismember(&t->real_blocked, sig) &&
984 (sig == SIGKILL || !(t->ptrace & PT_PTRACED))) {
986 * This signal will be fatal to the whole group.
988 if (!sig_kernel_coredump(sig)) {
990 * Start a group exit and wake everybody up.
991 * This way we don't have other threads
992 * running and doing things after a slower
993 * thread has the fatal signal pending.
995 p->signal->flags = SIGNAL_GROUP_EXIT;
996 p->signal->group_exit_code = sig;
997 p->signal->group_stop_count = 0;
1000 sigaddset(&t->pending.signal, SIGKILL);
1001 signal_wake_up(t, 1);
1008 * There will be a core dump. We make all threads other
1009 * than the chosen one go into a group stop so that nothing
1010 * happens until it gets scheduled, takes the signal off
1011 * the shared queue, and does the core dump. This is a
1012 * little more complicated than strictly necessary, but it
1013 * keeps the signal state that winds up in the core dump
1014 * unchanged from the death state, e.g. which thread had
1015 * the core-dump signal unblocked.
1017 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
1018 rm_from_queue(SIG_KERNEL_STOP_MASK, &p->signal->shared_pending);
1019 p->signal->group_stop_count = 0;
1020 p->signal->group_exit_task = t;
1023 p->signal->group_stop_count++;
1024 signal_wake_up(t, 0);
1027 wake_up_process(p->signal->group_exit_task);
1032 * The signal is already in the shared-pending queue.
1033 * Tell the chosen thread to wake up and dequeue it.
1035 signal_wake_up(t, sig == SIGKILL);
1040 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1044 assert_spin_locked(&p->sighand->siglock);
1045 handle_stop_signal(sig, p);
1047 if (((unsigned long)info > 2) && (info->si_code == SI_TIMER))
1049 * Set up a return to indicate that we dropped the signal.
1051 ret = info->si_sys_private;
1053 /* Short-circuit ignored signals. */
1054 if (sig_ignored(p, sig))
1057 if (LEGACY_QUEUE(&p->signal->shared_pending, sig))
1058 /* This is a non-RT signal and we already have one queued. */
1062 * Put this signal on the shared-pending queue, or fail with EAGAIN.
1063 * We always use the shared queue for process-wide signals,
1064 * to avoid several races.
1066 ret = send_signal(sig, info, p, &p->signal->shared_pending);
1070 __group_complete_signal(sig, p);
1075 * Nuke all other threads in the group.
1077 void zap_other_threads(struct task_struct *p)
1079 struct task_struct *t;
1081 p->signal->flags = SIGNAL_GROUP_EXIT;
1082 p->signal->group_stop_count = 0;
1084 if (thread_group_empty(p))
1087 for (t = next_thread(p); t != p; t = next_thread(t)) {
1089 * Don't bother with already dead threads
1095 * We don't want to notify the parent, since we are
1096 * killed as part of a thread group due to another
1097 * thread doing an execve() or similar. So set the
1098 * exit signal to -1 to allow immediate reaping of
1099 * the process. But don't detach the thread group
1102 if (t != p->group_leader)
1103 t->exit_signal = -1;
1105 sigaddset(&t->pending.signal, SIGKILL);
1106 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
1107 signal_wake_up(t, 1);
1112 * Must be called with the tasklist_lock held for reading!
1114 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1116 unsigned long flags;
1119 ret = check_kill_permission(sig, info, p);
1120 if (!ret && sig && p->sighand) {
1121 spin_lock_irqsave(&p->sighand->siglock, flags);
1122 ret = __group_send_sig_info(sig, info, p);
1123 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1130 * kill_pg_info() sends a signal to a process group: this is what the tty
1131 * control characters do (^C, ^Z etc)
1134 int __kill_pg_info(int sig, struct siginfo *info, pid_t pgrp)
1136 struct task_struct *p = NULL;
1137 int retval, success;
1144 do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
1145 int err = group_send_sig_info(sig, info, p);
1148 } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
1149 return success ? 0 : retval;
1153 kill_pg_info(int sig, struct siginfo *info, pid_t pgrp)
1157 read_lock(&tasklist_lock);
1158 retval = __kill_pg_info(sig, info, pgrp);
1159 read_unlock(&tasklist_lock);
1165 kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1168 struct task_struct *p;
1170 read_lock(&tasklist_lock);
1171 p = find_task_by_pid(pid);
1174 error = group_send_sig_info(sig, info, p);
1175 read_unlock(&tasklist_lock);
1181 * kill_something_info() interprets pid in interesting ways just like kill(2).
1183 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1184 * is probably wrong. Should make it like BSD or SYSV.
1187 static int kill_something_info(int sig, struct siginfo *info, int pid)
1190 return kill_pg_info(sig, info, process_group(current));
1191 } else if (pid == -1) {
1192 int retval = 0, count = 0;
1193 struct task_struct * p;
1195 read_lock(&tasklist_lock);
1196 for_each_process(p) {
1197 if (p->pid > 1 && p->tgid != current->tgid) {
1198 int err = group_send_sig_info(sig, info, p);
1204 read_unlock(&tasklist_lock);
1205 return count ? retval : -ESRCH;
1206 } else if (pid < 0) {
1207 return kill_pg_info(sig, info, -pid);
1209 return kill_proc_info(sig, info, pid);
1214 * These are for backward compatibility with the rest of the kernel source.
1218 * These two are the most common entry points. They send a signal
1219 * just to the specific thread.
1222 send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1225 unsigned long flags;
1228 * Make sure legacy kernel users don't send in bad values
1229 * (normal paths check this in check_kill_permission).
1231 if (sig < 0 || sig > _NSIG)
1235 * We need the tasklist lock even for the specific
1236 * thread case (when we don't need to follow the group
1237 * lists) in order to avoid races with "p->sighand"
1238 * going away or changing from under us.
1240 read_lock(&tasklist_lock);
1241 spin_lock_irqsave(&p->sighand->siglock, flags);
1242 ret = specific_send_sig_info(sig, info, p);
1243 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1244 read_unlock(&tasklist_lock);
1249 send_sig(int sig, struct task_struct *p, int priv)
1251 return send_sig_info(sig, (void*)(long)(priv != 0), p);
1255 * This is the entry point for "process-wide" signals.
1256 * They will go to an appropriate thread in the thread group.
1259 send_group_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1262 read_lock(&tasklist_lock);
1263 ret = group_send_sig_info(sig, info, p);
1264 read_unlock(&tasklist_lock);
1269 force_sig(int sig, struct task_struct *p)
1271 force_sig_info(sig, (void*)1L, p);
1275 * When things go south during signal handling, we
1276 * will force a SIGSEGV. And if the signal that caused
1277 * the problem was already a SIGSEGV, we'll want to
1278 * make sure we don't even try to deliver the signal..
1281 force_sigsegv(int sig, struct task_struct *p)
1283 if (sig == SIGSEGV) {
1284 unsigned long flags;
1285 spin_lock_irqsave(&p->sighand->siglock, flags);
1286 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1287 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1289 force_sig(SIGSEGV, p);
1294 kill_pg(pid_t pgrp, int sig, int priv)
1296 return kill_pg_info(sig, (void *)(long)(priv != 0), pgrp);
1300 kill_proc(pid_t pid, int sig, int priv)
1302 return kill_proc_info(sig, (void *)(long)(priv != 0), pid);
1306 * These functions support sending signals using preallocated sigqueue
1307 * structures. This is needed "because realtime applications cannot
1308 * afford to lose notifications of asynchronous events, like timer
1309 * expirations or I/O completions". In the case of Posix Timers
1310 * we allocate the sigqueue structure from the timer_create. If this
1311 * allocation fails we are able to report the failure to the application
1312 * with an EAGAIN error.
1315 struct sigqueue *sigqueue_alloc(void)
1319 if ((q = __sigqueue_alloc(current, GFP_KERNEL)))
1320 q->flags |= SIGQUEUE_PREALLOC;
1324 void sigqueue_free(struct sigqueue *q)
1326 unsigned long flags;
1327 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1329 * If the signal is still pending remove it from the
1332 if (unlikely(!list_empty(&q->list))) {
1333 read_lock(&tasklist_lock);
1334 spin_lock_irqsave(q->lock, flags);
1335 if (!list_empty(&q->list))
1336 list_del_init(&q->list);
1337 spin_unlock_irqrestore(q->lock, flags);
1338 read_unlock(&tasklist_lock);
1340 q->flags &= ~SIGQUEUE_PREALLOC;
1345 send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
1347 unsigned long flags;
1351 * We need the tasklist lock even for the specific
1352 * thread case (when we don't need to follow the group
1353 * lists) in order to avoid races with "p->sighand"
1354 * going away or changing from under us.
1356 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1357 read_lock(&tasklist_lock);
1358 spin_lock_irqsave(&p->sighand->siglock, flags);
1360 if (unlikely(!list_empty(&q->list))) {
1362 * If an SI_TIMER entry is already queue just increment
1363 * the overrun count.
1365 if (q->info.si_code != SI_TIMER)
1367 q->info.si_overrun++;
1370 /* Short-circuit ignored signals. */
1371 if (sig_ignored(p, sig)) {
1376 q->lock = &p->sighand->siglock;
1377 list_add_tail(&q->list, &p->pending.list);
1378 sigaddset(&p->pending.signal, sig);
1379 if (!sigismember(&p->blocked, sig))
1380 signal_wake_up(p, sig == SIGKILL);
1383 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1384 read_unlock(&tasklist_lock);
1389 send_group_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
1391 unsigned long flags;
1394 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1395 read_lock(&tasklist_lock);
1396 spin_lock_irqsave(&p->sighand->siglock, flags);
1397 handle_stop_signal(sig, p);
1399 /* Short-circuit ignored signals. */
1400 if (sig_ignored(p, sig)) {
1405 if (unlikely(!list_empty(&q->list))) {
1407 * If an SI_TIMER entry is already queue just increment
1408 * the overrun count. Other uses should not try to
1409 * send the signal multiple times.
1411 if (q->info.si_code != SI_TIMER)
1413 q->info.si_overrun++;
1418 * Put this signal on the shared-pending queue.
1419 * We always use the shared queue for process-wide signals,
1420 * to avoid several races.
1422 q->lock = &p->sighand->siglock;
1423 list_add_tail(&q->list, &p->signal->shared_pending.list);
1424 sigaddset(&p->signal->shared_pending.signal, sig);
1426 __group_complete_signal(sig, p);
1428 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1429 read_unlock(&tasklist_lock);
1434 * Wake up any threads in the parent blocked in wait* syscalls.
1436 static inline void __wake_up_parent(struct task_struct *p,
1437 struct task_struct *parent)
1439 wake_up_interruptible_sync(&parent->signal->wait_chldexit);
1443 * Let a parent know about the death of a child.
1444 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1447 void do_notify_parent(struct task_struct *tsk, int sig)
1449 struct siginfo info;
1450 unsigned long flags;
1451 struct sighand_struct *psig;
1455 /* do_notify_parent_cldstop should have been called instead. */
1456 BUG_ON(tsk->state & (TASK_STOPPED|TASK_TRACED));
1458 BUG_ON(!tsk->ptrace &&
1459 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1461 info.si_signo = sig;
1463 info.si_pid = tsk->pid;
1464 info.si_uid = tsk->uid;
1466 /* FIXME: find out whether or not this is supposed to be c*time. */
1467 info.si_utime = cputime_to_jiffies(cputime_add(tsk->utime,
1468 tsk->signal->utime));
1469 info.si_stime = cputime_to_jiffies(cputime_add(tsk->stime,
1470 tsk->signal->stime));
1472 info.si_status = tsk->exit_code & 0x7f;
1473 if (tsk->exit_code & 0x80)
1474 info.si_code = CLD_DUMPED;
1475 else if (tsk->exit_code & 0x7f)
1476 info.si_code = CLD_KILLED;
1478 info.si_code = CLD_EXITED;
1479 info.si_status = tsk->exit_code >> 8;
1482 psig = tsk->parent->sighand;
1483 spin_lock_irqsave(&psig->siglock, flags);
1484 if (sig == SIGCHLD &&
1485 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1486 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1488 * We are exiting and our parent doesn't care. POSIX.1
1489 * defines special semantics for setting SIGCHLD to SIG_IGN
1490 * or setting the SA_NOCLDWAIT flag: we should be reaped
1491 * automatically and not left for our parent's wait4 call.
1492 * Rather than having the parent do it as a magic kind of
1493 * signal handler, we just set this to tell do_exit that we
1494 * can be cleaned up without becoming a zombie. Note that
1495 * we still call __wake_up_parent in this case, because a
1496 * blocked sys_wait4 might now return -ECHILD.
1498 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1499 * is implementation-defined: we do (if you don't want
1500 * it, just use SIG_IGN instead).
1502 tsk->exit_signal = -1;
1503 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1506 if (sig > 0 && sig <= _NSIG)
1507 __group_send_sig_info(sig, &info, tsk->parent);
1508 __wake_up_parent(tsk, tsk->parent);
1509 spin_unlock_irqrestore(&psig->siglock, flags);
1513 do_notify_parent_cldstop(struct task_struct *tsk, struct task_struct *parent,
1516 struct siginfo info;
1517 unsigned long flags;
1518 struct sighand_struct *sighand;
1520 info.si_signo = SIGCHLD;
1522 info.si_pid = tsk->pid;
1523 info.si_uid = tsk->uid;
1525 /* FIXME: find out whether or not this is supposed to be c*time. */
1526 info.si_utime = cputime_to_jiffies(tsk->utime);
1527 info.si_stime = cputime_to_jiffies(tsk->stime);
1532 info.si_status = SIGCONT;
1535 info.si_status = tsk->signal->group_exit_code & 0x7f;
1538 info.si_status = tsk->exit_code & 0x7f;
1544 sighand = parent->sighand;
1545 spin_lock_irqsave(&sighand->siglock, flags);
1546 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1547 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1548 __group_send_sig_info(SIGCHLD, &info, parent);
1550 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1552 __wake_up_parent(tsk, parent);
1553 spin_unlock_irqrestore(&sighand->siglock, flags);
1557 * This must be called with current->sighand->siglock held.
1559 * This should be the path for all ptrace stops.
1560 * We always set current->last_siginfo while stopped here.
1561 * That makes it a way to test a stopped process for
1562 * being ptrace-stopped vs being job-control-stopped.
1564 * If we actually decide not to stop at all because the tracer is gone,
1565 * we leave nostop_code in current->exit_code.
1567 static void ptrace_stop(int exit_code, int nostop_code, siginfo_t *info)
1570 * If there is a group stop in progress,
1571 * we must participate in the bookkeeping.
1573 if (current->signal->group_stop_count > 0)
1574 --current->signal->group_stop_count;
1576 current->last_siginfo = info;
1577 current->exit_code = exit_code;
1579 /* Let the debugger run. */
1580 set_current_state(TASK_TRACED);
1581 spin_unlock_irq(¤t->sighand->siglock);
1582 read_lock(&tasklist_lock);
1583 if (likely(current->ptrace & PT_PTRACED) &&
1584 likely(current->parent != current->real_parent ||
1585 !(current->ptrace & PT_ATTACHED)) &&
1586 (likely(current->parent->signal != current->signal) ||
1587 !unlikely(current->signal->flags & SIGNAL_GROUP_EXIT))) {
1588 do_notify_parent_cldstop(current, current->parent,
1590 read_unlock(&tasklist_lock);
1594 * By the time we got the lock, our tracer went away.
1597 read_unlock(&tasklist_lock);
1598 set_current_state(TASK_RUNNING);
1599 current->exit_code = nostop_code;
1603 * We are back. Now reacquire the siglock before touching
1604 * last_siginfo, so that we are sure to have synchronized with
1605 * any signal-sending on another CPU that wants to examine it.
1607 spin_lock_irq(¤t->sighand->siglock);
1608 current->last_siginfo = NULL;
1611 * Queued signals ignored us while we were stopped for tracing.
1612 * So check for any that we should take before resuming user mode.
1614 recalc_sigpending();
1617 void ptrace_notify(int exit_code)
1621 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1623 memset(&info, 0, sizeof info);
1624 info.si_signo = SIGTRAP;
1625 info.si_code = exit_code;
1626 info.si_pid = current->pid;
1627 info.si_uid = current->uid;
1629 /* Let the debugger run. */
1630 spin_lock_irq(¤t->sighand->siglock);
1631 ptrace_stop(exit_code, 0, &info);
1632 spin_unlock_irq(¤t->sighand->siglock);
1635 #ifndef HAVE_ARCH_GET_SIGNAL_TO_DELIVER
1638 finish_stop(int stop_count)
1641 * If there are no other threads in the group, or if there is
1642 * a group stop in progress and we are the last to stop,
1643 * report to the parent. When ptraced, every thread reports itself.
1645 if (stop_count < 0 || (current->ptrace & PT_PTRACED)) {
1646 read_lock(&tasklist_lock);
1647 do_notify_parent_cldstop(current, current->parent,
1649 read_unlock(&tasklist_lock);
1651 else if (stop_count == 0) {
1652 read_lock(&tasklist_lock);
1653 do_notify_parent_cldstop(current->group_leader,
1654 current->group_leader->real_parent,
1656 read_unlock(&tasklist_lock);
1661 * Now we don't run again until continued.
1663 current->exit_code = 0;
1667 * This performs the stopping for SIGSTOP and other stop signals.
1668 * We have to stop all threads in the thread group.
1669 * Returns nonzero if we've actually stopped and released the siglock.
1670 * Returns zero if we didn't stop and still hold the siglock.
1673 do_signal_stop(int signr)
1675 struct signal_struct *sig = current->signal;
1676 struct sighand_struct *sighand = current->sighand;
1677 int stop_count = -1;
1679 if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED))
1682 if (sig->group_stop_count > 0) {
1684 * There is a group stop in progress. We don't need to
1685 * start another one.
1687 signr = sig->group_exit_code;
1688 stop_count = --sig->group_stop_count;
1689 current->exit_code = signr;
1690 set_current_state(TASK_STOPPED);
1691 if (stop_count == 0)
1692 sig->flags = SIGNAL_STOP_STOPPED;
1693 spin_unlock_irq(&sighand->siglock);
1695 else if (thread_group_empty(current)) {
1697 * Lock must be held through transition to stopped state.
1699 current->exit_code = current->signal->group_exit_code = signr;
1700 set_current_state(TASK_STOPPED);
1701 sig->flags = SIGNAL_STOP_STOPPED;
1702 spin_unlock_irq(&sighand->siglock);
1706 * There is no group stop already in progress.
1707 * We must initiate one now, but that requires
1708 * dropping siglock to get both the tasklist lock
1709 * and siglock again in the proper order. Note that
1710 * this allows an intervening SIGCONT to be posted.
1711 * We need to check for that and bail out if necessary.
1713 struct task_struct *t;
1715 spin_unlock_irq(&sighand->siglock);
1717 /* signals can be posted during this window */
1719 read_lock(&tasklist_lock);
1720 spin_lock_irq(&sighand->siglock);
1722 if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED)) {
1724 * Another stop or continue happened while we
1725 * didn't have the lock. We can just swallow this
1726 * signal now. If we raced with a SIGCONT, that
1727 * should have just cleared it now. If we raced
1728 * with another processor delivering a stop signal,
1729 * then the SIGCONT that wakes us up should clear it.
1731 read_unlock(&tasklist_lock);
1735 if (sig->group_stop_count == 0) {
1736 sig->group_exit_code = signr;
1738 for (t = next_thread(current); t != current;
1741 * Setting state to TASK_STOPPED for a group
1742 * stop is always done with the siglock held,
1743 * so this check has no races.
1745 if (t->state < TASK_STOPPED) {
1747 signal_wake_up(t, 0);
1749 sig->group_stop_count = stop_count;
1752 /* A race with another thread while unlocked. */
1753 signr = sig->group_exit_code;
1754 stop_count = --sig->group_stop_count;
1757 current->exit_code = signr;
1758 set_current_state(TASK_STOPPED);
1759 if (stop_count == 0)
1760 sig->flags = SIGNAL_STOP_STOPPED;
1762 spin_unlock_irq(&sighand->siglock);
1763 read_unlock(&tasklist_lock);
1766 finish_stop(stop_count);
1771 * Do appropriate magic when group_stop_count > 0.
1772 * We return nonzero if we stopped, after releasing the siglock.
1773 * We return zero if we still hold the siglock and should look
1774 * for another signal without checking group_stop_count again.
1776 static inline int handle_group_stop(void)
1780 if (current->signal->group_exit_task == current) {
1782 * Group stop is so we can do a core dump,
1783 * We are the initiating thread, so get on with it.
1785 current->signal->group_exit_task = NULL;
1789 if (current->signal->flags & SIGNAL_GROUP_EXIT)
1791 * Group stop is so another thread can do a core dump,
1792 * or else we are racing against a death signal.
1793 * Just punt the stop so we can get the next signal.
1798 * There is a group stop in progress. We stop
1799 * without any associated signal being in our queue.
1801 stop_count = --current->signal->group_stop_count;
1802 if (stop_count == 0)
1803 current->signal->flags = SIGNAL_STOP_STOPPED;
1804 current->exit_code = current->signal->group_exit_code;
1805 set_current_state(TASK_STOPPED);
1806 spin_unlock_irq(¤t->sighand->siglock);
1807 finish_stop(stop_count);
1811 int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
1812 struct pt_regs *regs, void *cookie)
1814 sigset_t *mask = ¤t->blocked;
1818 spin_lock_irq(¤t->sighand->siglock);
1820 struct k_sigaction *ka;
1822 if (unlikely(current->signal->group_stop_count > 0) &&
1823 handle_group_stop())
1826 signr = dequeue_signal(current, mask, info);
1829 break; /* will return 0 */
1831 if ((current->ptrace & PT_PTRACED) && signr != SIGKILL) {
1832 ptrace_signal_deliver(regs, cookie);
1834 /* Let the debugger run. */
1835 ptrace_stop(signr, signr, info);
1837 /* We're back. Did the debugger cancel the sig? */
1838 signr = current->exit_code;
1842 current->exit_code = 0;
1844 /* Update the siginfo structure if the signal has
1845 changed. If the debugger wanted something
1846 specific in the siginfo structure then it should
1847 have updated *info via PTRACE_SETSIGINFO. */
1848 if (signr != info->si_signo) {
1849 info->si_signo = signr;
1851 info->si_code = SI_USER;
1852 info->si_pid = current->parent->pid;
1853 info->si_uid = current->parent->uid;
1856 /* If the (new) signal is now blocked, requeue it. */
1857 if (sigismember(¤t->blocked, signr)) {
1858 specific_send_sig_info(signr, info, current);
1863 ka = ¤t->sighand->action[signr-1];
1864 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
1866 if (ka->sa.sa_handler != SIG_DFL) {
1867 /* Run the handler. */
1870 if (ka->sa.sa_flags & SA_ONESHOT)
1871 ka->sa.sa_handler = SIG_DFL;
1873 break; /* will return non-zero "signr" value */
1877 * Now we are doing the default action for this signal.
1879 if (sig_kernel_ignore(signr)) /* Default is nothing. */
1882 /* Init gets no signals it doesn't want. */
1883 if (current->pid == 1)
1886 if (sig_kernel_stop(signr)) {
1888 * The default action is to stop all threads in
1889 * the thread group. The job control signals
1890 * do nothing in an orphaned pgrp, but SIGSTOP
1891 * always works. Note that siglock needs to be
1892 * dropped during the call to is_orphaned_pgrp()
1893 * because of lock ordering with tasklist_lock.
1894 * This allows an intervening SIGCONT to be posted.
1895 * We need to check for that and bail out if necessary.
1897 if (signr != SIGSTOP) {
1898 spin_unlock_irq(¤t->sighand->siglock);
1900 /* signals can be posted during this window */
1902 if (is_orphaned_pgrp(process_group(current)))
1905 spin_lock_irq(¤t->sighand->siglock);
1908 if (likely(do_signal_stop(signr))) {
1909 /* It released the siglock. */
1914 * We didn't actually stop, due to a race
1915 * with SIGCONT or something like that.
1920 spin_unlock_irq(¤t->sighand->siglock);
1923 * Anything else is fatal, maybe with a core dump.
1925 current->flags |= PF_SIGNALED;
1926 if (sig_kernel_coredump(signr)) {
1928 * If it was able to dump core, this kills all
1929 * other threads in the group and synchronizes with
1930 * their demise. If we lost the race with another
1931 * thread getting here, it set group_exit_code
1932 * first and our do_group_exit call below will use
1933 * that value and ignore the one we pass it.
1935 do_coredump((long)signr, signr, regs);
1939 * Death signals, no core dump.
1941 do_group_exit(signr);
1944 spin_unlock_irq(¤t->sighand->siglock);
1950 EXPORT_SYMBOL(recalc_sigpending);
1951 EXPORT_SYMBOL_GPL(dequeue_signal);
1952 EXPORT_SYMBOL(flush_signals);
1953 EXPORT_SYMBOL(force_sig);
1954 EXPORT_SYMBOL(kill_pg);
1955 EXPORT_SYMBOL(kill_proc);
1956 EXPORT_SYMBOL(ptrace_notify);
1957 EXPORT_SYMBOL(send_sig);
1958 EXPORT_SYMBOL(send_sig_info);
1959 EXPORT_SYMBOL(sigprocmask);
1960 EXPORT_SYMBOL(block_all_signals);
1961 EXPORT_SYMBOL(unblock_all_signals);
1965 * System call entry points.
1968 asmlinkage long sys_restart_syscall(void)
1970 struct restart_block *restart = ¤t_thread_info()->restart_block;
1971 return restart->fn(restart);
1974 long do_no_restart_syscall(struct restart_block *param)
1980 * We don't need to get the kernel lock - this is all local to this
1981 * particular thread.. (and that's good, because this is _heavily_
1982 * used by various programs)
1986 * This is also useful for kernel threads that want to temporarily
1987 * (or permanently) block certain signals.
1989 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
1990 * interface happily blocks "unblockable" signals like SIGKILL
1993 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
1998 spin_lock_irq(¤t->sighand->siglock);
1999 old_block = current->blocked;
2003 sigorsets(¤t->blocked, ¤t->blocked, set);
2006 signandsets(¤t->blocked, ¤t->blocked, set);
2009 current->blocked = *set;
2014 recalc_sigpending();
2015 spin_unlock_irq(¤t->sighand->siglock);
2017 *oldset = old_block;
2022 sys_rt_sigprocmask(int how, sigset_t __user *set, sigset_t __user *oset, size_t sigsetsize)
2024 int error = -EINVAL;
2025 sigset_t old_set, new_set;
2027 /* XXX: Don't preclude handling different sized sigset_t's. */
2028 if (sigsetsize != sizeof(sigset_t))
2033 if (copy_from_user(&new_set, set, sizeof(*set)))
2035 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2037 error = sigprocmask(how, &new_set, &old_set);
2043 spin_lock_irq(¤t->sighand->siglock);
2044 old_set = current->blocked;
2045 spin_unlock_irq(¤t->sighand->siglock);
2049 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2057 long do_sigpending(void __user *set, unsigned long sigsetsize)
2059 long error = -EINVAL;
2062 if (sigsetsize > sizeof(sigset_t))
2065 spin_lock_irq(¤t->sighand->siglock);
2066 sigorsets(&pending, ¤t->pending.signal,
2067 ¤t->signal->shared_pending.signal);
2068 spin_unlock_irq(¤t->sighand->siglock);
2070 /* Outside the lock because only this thread touches it. */
2071 sigandsets(&pending, ¤t->blocked, &pending);
2074 if (!copy_to_user(set, &pending, sigsetsize))
2082 sys_rt_sigpending(sigset_t __user *set, size_t sigsetsize)
2084 return do_sigpending(set, sigsetsize);
2087 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2089 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2093 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2095 if (from->si_code < 0)
2096 return __copy_to_user(to, from, sizeof(siginfo_t))
2099 * If you change siginfo_t structure, please be sure
2100 * this code is fixed accordingly.
2101 * It should never copy any pad contained in the structure
2102 * to avoid security leaks, but must copy the generic
2103 * 3 ints plus the relevant union member.
2105 err = __put_user(from->si_signo, &to->si_signo);
2106 err |= __put_user(from->si_errno, &to->si_errno);
2107 err |= __put_user((short)from->si_code, &to->si_code);
2108 switch (from->si_code & __SI_MASK) {
2110 err |= __put_user(from->si_pid, &to->si_pid);
2111 err |= __put_user(from->si_uid, &to->si_uid);
2114 err |= __put_user(from->si_tid, &to->si_tid);
2115 err |= __put_user(from->si_overrun, &to->si_overrun);
2116 err |= __put_user(from->si_ptr, &to->si_ptr);
2119 err |= __put_user(from->si_band, &to->si_band);
2120 err |= __put_user(from->si_fd, &to->si_fd);
2123 err |= __put_user(from->si_addr, &to->si_addr);
2124 #ifdef __ARCH_SI_TRAPNO
2125 err |= __put_user(from->si_trapno, &to->si_trapno);
2129 err |= __put_user(from->si_pid, &to->si_pid);
2130 err |= __put_user(from->si_uid, &to->si_uid);
2131 err |= __put_user(from->si_status, &to->si_status);
2132 err |= __put_user(from->si_utime, &to->si_utime);
2133 err |= __put_user(from->si_stime, &to->si_stime);
2135 case __SI_RT: /* This is not generated by the kernel as of now. */
2136 case __SI_MESGQ: /* But this is */
2137 err |= __put_user(from->si_pid, &to->si_pid);
2138 err |= __put_user(from->si_uid, &to->si_uid);
2139 err |= __put_user(from->si_ptr, &to->si_ptr);
2141 default: /* this is just in case for now ... */
2142 err |= __put_user(from->si_pid, &to->si_pid);
2143 err |= __put_user(from->si_uid, &to->si_uid);
2152 sys_rt_sigtimedwait(const sigset_t __user *uthese,
2153 siginfo_t __user *uinfo,
2154 const struct timespec __user *uts,
2163 /* XXX: Don't preclude handling different sized sigset_t's. */
2164 if (sigsetsize != sizeof(sigset_t))
2167 if (copy_from_user(&these, uthese, sizeof(these)))
2171 * Invert the set of allowed signals to get those we
2174 sigdelsetmask(&these, sigmask(SIGKILL)|sigmask(SIGSTOP));
2178 if (copy_from_user(&ts, uts, sizeof(ts)))
2180 if (ts.tv_nsec >= 1000000000L || ts.tv_nsec < 0
2185 spin_lock_irq(¤t->sighand->siglock);
2186 sig = dequeue_signal(current, &these, &info);
2188 timeout = MAX_SCHEDULE_TIMEOUT;
2190 timeout = (timespec_to_jiffies(&ts)
2191 + (ts.tv_sec || ts.tv_nsec));
2194 /* None ready -- temporarily unblock those we're
2195 * interested while we are sleeping in so that we'll
2196 * be awakened when they arrive. */
2197 current->real_blocked = current->blocked;
2198 sigandsets(¤t->blocked, ¤t->blocked, &these);
2199 recalc_sigpending();
2200 spin_unlock_irq(¤t->sighand->siglock);
2202 current->state = TASK_INTERRUPTIBLE;
2203 timeout = schedule_timeout(timeout);
2205 spin_lock_irq(¤t->sighand->siglock);
2206 sig = dequeue_signal(current, &these, &info);
2207 current->blocked = current->real_blocked;
2208 siginitset(¤t->real_blocked, 0);
2209 recalc_sigpending();
2212 spin_unlock_irq(¤t->sighand->siglock);
2217 if (copy_siginfo_to_user(uinfo, &info))
2230 sys_kill(int pid, int sig)
2232 struct siginfo info;
2234 info.si_signo = sig;
2236 info.si_code = SI_USER;
2237 info.si_pid = current->tgid;
2238 info.si_uid = current->uid;
2240 return kill_something_info(sig, &info, pid);
2244 * sys_tgkill - send signal to one specific thread
2245 * @tgid: the thread group ID of the thread
2246 * @pid: the PID of the thread
2247 * @sig: signal to be sent
2249 * This syscall also checks the tgid and returns -ESRCH even if the PID
2250 * exists but it's not belonging to the target process anymore. This
2251 * method solves the problem of threads exiting and PIDs getting reused.
2253 asmlinkage long sys_tgkill(int tgid, int pid, int sig)
2255 struct siginfo info;
2257 struct task_struct *p;
2259 /* This is only valid for single tasks */
2260 if (pid <= 0 || tgid <= 0)
2263 info.si_signo = sig;
2265 info.si_code = SI_TKILL;
2266 info.si_pid = current->tgid;
2267 info.si_uid = current->uid;
2269 read_lock(&tasklist_lock);
2270 p = find_task_by_pid(pid);
2272 if (p && (p->tgid == tgid)) {
2273 error = check_kill_permission(sig, &info, p);
2275 * The null signal is a permissions and process existence
2276 * probe. No signal is actually delivered.
2278 if (!error && sig && p->sighand) {
2279 spin_lock_irq(&p->sighand->siglock);
2280 handle_stop_signal(sig, p);
2281 error = specific_send_sig_info(sig, &info, p);
2282 spin_unlock_irq(&p->sighand->siglock);
2285 read_unlock(&tasklist_lock);
2290 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2293 sys_tkill(int pid, int sig)
2295 struct siginfo info;
2297 struct task_struct *p;
2299 /* This is only valid for single tasks */
2303 info.si_signo = sig;
2305 info.si_code = SI_TKILL;
2306 info.si_pid = current->tgid;
2307 info.si_uid = current->uid;
2309 read_lock(&tasklist_lock);
2310 p = find_task_by_pid(pid);
2313 error = check_kill_permission(sig, &info, p);
2315 * The null signal is a permissions and process existence
2316 * probe. No signal is actually delivered.
2318 if (!error && sig && p->sighand) {
2319 spin_lock_irq(&p->sighand->siglock);
2320 handle_stop_signal(sig, p);
2321 error = specific_send_sig_info(sig, &info, p);
2322 spin_unlock_irq(&p->sighand->siglock);
2325 read_unlock(&tasklist_lock);
2330 sys_rt_sigqueueinfo(int pid, int sig, siginfo_t __user *uinfo)
2334 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2337 /* Not even root can pretend to send signals from the kernel.
2338 Nor can they impersonate a kill(), which adds source info. */
2339 if (info.si_code >= 0)
2341 info.si_signo = sig;
2343 /* POSIX.1b doesn't mention process groups. */
2344 return kill_proc_info(sig, &info, pid);
2348 do_sigaction(int sig, const struct k_sigaction *act, struct k_sigaction *oact)
2350 struct k_sigaction *k;
2352 if (sig < 1 || sig > _NSIG || (act && sig_kernel_only(sig)))
2355 k = ¤t->sighand->action[sig-1];
2357 spin_lock_irq(¤t->sighand->siglock);
2358 if (signal_pending(current)) {
2360 * If there might be a fatal signal pending on multiple
2361 * threads, make sure we take it before changing the action.
2363 spin_unlock_irq(¤t->sighand->siglock);
2364 return -ERESTARTNOINTR;
2373 * "Setting a signal action to SIG_IGN for a signal that is
2374 * pending shall cause the pending signal to be discarded,
2375 * whether or not it is blocked."
2377 * "Setting a signal action to SIG_DFL for a signal that is
2378 * pending and whose default action is to ignore the signal
2379 * (for example, SIGCHLD), shall cause the pending signal to
2380 * be discarded, whether or not it is blocked"
2382 if (act->sa.sa_handler == SIG_IGN ||
2383 (act->sa.sa_handler == SIG_DFL &&
2384 sig_kernel_ignore(sig))) {
2386 * This is a fairly rare case, so we only take the
2387 * tasklist_lock once we're sure we'll need it.
2388 * Now we must do this little unlock and relock
2389 * dance to maintain the lock hierarchy.
2391 struct task_struct *t = current;
2392 spin_unlock_irq(&t->sighand->siglock);
2393 read_lock(&tasklist_lock);
2394 spin_lock_irq(&t->sighand->siglock);
2396 sigdelsetmask(&k->sa.sa_mask,
2397 sigmask(SIGKILL) | sigmask(SIGSTOP));
2398 rm_from_queue(sigmask(sig), &t->signal->shared_pending);
2400 rm_from_queue(sigmask(sig), &t->pending);
2401 recalc_sigpending_tsk(t);
2403 } while (t != current);
2404 spin_unlock_irq(¤t->sighand->siglock);
2405 read_unlock(&tasklist_lock);
2410 sigdelsetmask(&k->sa.sa_mask,
2411 sigmask(SIGKILL) | sigmask(SIGSTOP));
2414 spin_unlock_irq(¤t->sighand->siglock);
2419 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
2425 oss.ss_sp = (void __user *) current->sas_ss_sp;
2426 oss.ss_size = current->sas_ss_size;
2427 oss.ss_flags = sas_ss_flags(sp);
2436 if (verify_area(VERIFY_READ, uss, sizeof(*uss))
2437 || __get_user(ss_sp, &uss->ss_sp)
2438 || __get_user(ss_flags, &uss->ss_flags)
2439 || __get_user(ss_size, &uss->ss_size))
2443 if (on_sig_stack(sp))
2449 * Note - this code used to test ss_flags incorrectly
2450 * old code may have been written using ss_flags==0
2451 * to mean ss_flags==SS_ONSTACK (as this was the only
2452 * way that worked) - this fix preserves that older
2455 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
2458 if (ss_flags == SS_DISABLE) {
2463 if (ss_size < MINSIGSTKSZ)
2467 current->sas_ss_sp = (unsigned long) ss_sp;
2468 current->sas_ss_size = ss_size;
2473 if (copy_to_user(uoss, &oss, sizeof(oss)))
2482 #ifdef __ARCH_WANT_SYS_SIGPENDING
2485 sys_sigpending(old_sigset_t __user *set)
2487 return do_sigpending(set, sizeof(*set));
2492 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
2493 /* Some platforms have their own version with special arguments others
2494 support only sys_rt_sigprocmask. */
2497 sys_sigprocmask(int how, old_sigset_t __user *set, old_sigset_t __user *oset)
2500 old_sigset_t old_set, new_set;
2504 if (copy_from_user(&new_set, set, sizeof(*set)))
2506 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
2508 spin_lock_irq(¤t->sighand->siglock);
2509 old_set = current->blocked.sig[0];
2517 sigaddsetmask(¤t->blocked, new_set);
2520 sigdelsetmask(¤t->blocked, new_set);
2523 current->blocked.sig[0] = new_set;
2527 recalc_sigpending();
2528 spin_unlock_irq(¤t->sighand->siglock);
2534 old_set = current->blocked.sig[0];
2537 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2544 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
2546 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
2548 sys_rt_sigaction(int sig,
2549 const struct sigaction __user *act,
2550 struct sigaction __user *oact,
2553 struct k_sigaction new_sa, old_sa;
2556 /* XXX: Don't preclude handling different sized sigset_t's. */
2557 if (sigsetsize != sizeof(sigset_t))
2561 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
2565 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
2568 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
2574 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
2576 #ifdef __ARCH_WANT_SYS_SGETMASK
2579 * For backwards compatibility. Functionality superseded by sigprocmask.
2585 return current->blocked.sig[0];
2589 sys_ssetmask(int newmask)
2593 spin_lock_irq(¤t->sighand->siglock);
2594 old = current->blocked.sig[0];
2596 siginitset(¤t->blocked, newmask & ~(sigmask(SIGKILL)|
2598 recalc_sigpending();
2599 spin_unlock_irq(¤t->sighand->siglock);
2603 #endif /* __ARCH_WANT_SGETMASK */
2605 #ifdef __ARCH_WANT_SYS_SIGNAL
2607 * For backwards compatibility. Functionality superseded by sigaction.
2609 asmlinkage unsigned long
2610 sys_signal(int sig, __sighandler_t handler)
2612 struct k_sigaction new_sa, old_sa;
2615 new_sa.sa.sa_handler = handler;
2616 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
2618 ret = do_sigaction(sig, &new_sa, &old_sa);
2620 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
2622 #endif /* __ARCH_WANT_SYS_SIGNAL */
2624 #ifdef __ARCH_WANT_SYS_PAUSE
2629 current->state = TASK_INTERRUPTIBLE;
2631 return -ERESTARTNOHAND;
2636 void __init signals_init(void)
2639 kmem_cache_create("sigqueue",
2640 sizeof(struct sigqueue),
2641 __alignof__(struct sigqueue),
2642 SLAB_PANIC, NULL, NULL);