2 * linux/kernel/signal.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
6 * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
8 * 2003-06-02 Jim Houston - Concurrent Computer Corp.
9 * Changes to use preallocated sigqueue structures
10 * to allow signals to be sent reliably.
13 #include <linux/config.h>
14 #include <linux/slab.h>
15 #include <linux/module.h>
16 #include <linux/smp_lock.h>
17 #include <linux/init.h>
18 #include <linux/sched.h>
20 #include <linux/tty.h>
21 #include <linux/binfmts.h>
22 #include <linux/security.h>
23 #include <linux/ptrace.h>
24 #include <asm/param.h>
25 #include <asm/uaccess.h>
26 #include <asm/unistd.h>
27 #include <asm/siginfo.h>
30 * SLAB caches for signal bits.
33 static kmem_cache_t *sigqueue_cachep;
36 * In POSIX a signal is sent either to a specific thread (Linux task)
37 * or to the process as a whole (Linux thread group). How the signal
38 * is sent determines whether it's to one thread or the whole group,
39 * which determines which signal mask(s) are involved in blocking it
40 * from being delivered until later. When the signal is delivered,
41 * either it's caught or ignored by a user handler or it has a default
42 * effect that applies to the whole thread group (POSIX process).
44 * The possible effects an unblocked signal set to SIG_DFL can have are:
45 * ignore - Nothing Happens
46 * terminate - kill the process, i.e. all threads in the group,
47 * similar to exit_group. The group leader (only) reports
48 * WIFSIGNALED status to its parent.
49 * coredump - write a core dump file describing all threads using
50 * the same mm and then kill all those threads
51 * stop - stop all the threads in the group, i.e. TASK_STOPPED state
53 * SIGKILL and SIGSTOP cannot be caught, blocked, or ignored.
54 * Other signals when not blocked and set to SIG_DFL behaves as follows.
55 * The job control signals also have other special effects.
57 * +--------------------+------------------+
58 * | POSIX signal | default action |
59 * +--------------------+------------------+
60 * | SIGHUP | terminate |
61 * | SIGINT | terminate |
62 * | SIGQUIT | coredump |
63 * | SIGILL | coredump |
64 * | SIGTRAP | coredump |
65 * | SIGABRT/SIGIOT | coredump |
66 * | SIGBUS | coredump |
67 * | SIGFPE | coredump |
68 * | SIGKILL | terminate(+) |
69 * | SIGUSR1 | terminate |
70 * | SIGSEGV | coredump |
71 * | SIGUSR2 | terminate |
72 * | SIGPIPE | terminate |
73 * | SIGALRM | terminate |
74 * | SIGTERM | terminate |
75 * | SIGCHLD | ignore |
76 * | SIGCONT | ignore(*) |
77 * | SIGSTOP | stop(*)(+) |
78 * | SIGTSTP | stop(*) |
79 * | SIGTTIN | stop(*) |
80 * | SIGTTOU | stop(*) |
82 * | SIGXCPU | coredump |
83 * | SIGXFSZ | coredump |
84 * | SIGVTALRM | terminate |
85 * | SIGPROF | terminate |
86 * | SIGPOLL/SIGIO | terminate |
87 * | SIGSYS/SIGUNUSED | coredump |
88 * | SIGSTKFLT | terminate |
89 * | SIGWINCH | ignore |
90 * | SIGPWR | terminate |
91 * | SIGRTMIN-SIGRTMAX | terminate |
92 * +--------------------+------------------+
93 * | non-POSIX signal | default action |
94 * +--------------------+------------------+
95 * | SIGEMT | coredump |
96 * +--------------------+------------------+
98 * (+) For SIGKILL and SIGSTOP the action is "always", not just "default".
99 * (*) Special job control effects:
100 * When SIGCONT is sent, it resumes the process (all threads in the group)
101 * from TASK_STOPPED state and also clears any pending/queued stop signals
102 * (any of those marked with "stop(*)"). This happens regardless of blocking,
103 * catching, or ignoring SIGCONT. When any stop signal is sent, it clears
104 * any pending/queued SIGCONT signals; this happens regardless of blocking,
105 * catching, or ignored the stop signal, though (except for SIGSTOP) the
106 * default action of stopping the process may happen later or never.
110 #define M_SIGEMT M(SIGEMT)
115 #if SIGRTMIN > BITS_PER_LONG
116 #define M(sig) (1ULL << ((sig)-1))
118 #define M(sig) (1UL << ((sig)-1))
120 #define T(sig, mask) (M(sig) & (mask))
122 #define SIG_KERNEL_ONLY_MASK (\
123 M(SIGKILL) | M(SIGSTOP) )
125 #define SIG_KERNEL_STOP_MASK (\
126 M(SIGSTOP) | M(SIGTSTP) | M(SIGTTIN) | M(SIGTTOU) )
128 #define SIG_KERNEL_COREDUMP_MASK (\
129 M(SIGQUIT) | M(SIGILL) | M(SIGTRAP) | M(SIGABRT) | \
130 M(SIGFPE) | M(SIGSEGV) | M(SIGBUS) | M(SIGSYS) | \
131 M(SIGXCPU) | M(SIGXFSZ) | M_SIGEMT )
133 #define SIG_KERNEL_IGNORE_MASK (\
134 M(SIGCONT) | M(SIGCHLD) | M(SIGWINCH) | M(SIGURG) )
136 #define sig_kernel_only(sig) \
137 (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_ONLY_MASK))
138 #define sig_kernel_coredump(sig) \
139 (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_COREDUMP_MASK))
140 #define sig_kernel_ignore(sig) \
141 (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_IGNORE_MASK))
142 #define sig_kernel_stop(sig) \
143 (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_STOP_MASK))
145 #define sig_user_defined(t, signr) \
146 (((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_DFL) && \
147 ((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_IGN))
149 #define sig_fatal(t, signr) \
150 (!T(signr, SIG_KERNEL_IGNORE_MASK|SIG_KERNEL_STOP_MASK) && \
151 (t)->sighand->action[(signr)-1].sa.sa_handler == SIG_DFL)
153 #define sig_avoid_stop_race() \
154 (sigtestsetmask(¤t->pending.signal, M(SIGCONT) | M(SIGKILL)) || \
155 sigtestsetmask(¤t->signal->shared_pending.signal, \
156 M(SIGCONT) | M(SIGKILL)))
158 static int sig_ignored(struct task_struct *t, int sig)
160 void __user * handler;
163 * Tracers always want to know about signals..
165 if (t->ptrace & PT_PTRACED)
169 * Blocked signals are never ignored, since the
170 * signal handler may change by the time it is
173 if (sigismember(&t->blocked, sig))
176 /* Is it explicitly or implicitly ignored? */
177 handler = t->sighand->action[sig-1].sa.sa_handler;
178 return handler == SIG_IGN ||
179 (handler == SIG_DFL && sig_kernel_ignore(sig));
183 * Re-calculate pending state from the set of locally pending
184 * signals, globally pending signals, and blocked signals.
186 static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
191 switch (_NSIG_WORDS) {
193 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
194 ready |= signal->sig[i] &~ blocked->sig[i];
197 case 4: ready = signal->sig[3] &~ blocked->sig[3];
198 ready |= signal->sig[2] &~ blocked->sig[2];
199 ready |= signal->sig[1] &~ blocked->sig[1];
200 ready |= signal->sig[0] &~ blocked->sig[0];
203 case 2: ready = signal->sig[1] &~ blocked->sig[1];
204 ready |= signal->sig[0] &~ blocked->sig[0];
207 case 1: ready = signal->sig[0] &~ blocked->sig[0];
212 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
214 fastcall void recalc_sigpending_tsk(struct task_struct *t)
216 if (t->signal->group_stop_count > 0 ||
217 PENDING(&t->pending, &t->blocked) ||
218 PENDING(&t->signal->shared_pending, &t->blocked))
219 set_tsk_thread_flag(t, TIF_SIGPENDING);
221 clear_tsk_thread_flag(t, TIF_SIGPENDING);
224 void recalc_sigpending(void)
226 recalc_sigpending_tsk(current);
229 /* Given the mask, find the first available signal that should be serviced. */
232 next_signal(struct sigpending *pending, sigset_t *mask)
234 unsigned long i, *s, *m, x;
237 s = pending->signal.sig;
239 switch (_NSIG_WORDS) {
241 for (i = 0; i < _NSIG_WORDS; ++i, ++s, ++m)
242 if ((x = *s &~ *m) != 0) {
243 sig = ffz(~x) + i*_NSIG_BPW + 1;
248 case 2: if ((x = s[0] &~ m[0]) != 0)
250 else if ((x = s[1] &~ m[1]) != 0)
257 case 1: if ((x = *s &~ *m) != 0)
265 static struct sigqueue *__sigqueue_alloc(void)
267 struct sigqueue *q = NULL;
269 if (atomic_read(¤t->user->sigpending) <
270 current->rlim[RLIMIT_SIGPENDING].rlim_cur)
271 q = kmem_cache_alloc(sigqueue_cachep, GFP_ATOMIC);
273 INIT_LIST_HEAD(&q->list);
276 q->user = get_uid(current->user);
277 atomic_inc(&q->user->sigpending);
282 static inline void __sigqueue_free(struct sigqueue *q)
284 if (q->flags & SIGQUEUE_PREALLOC)
286 atomic_dec(&q->user->sigpending);
288 kmem_cache_free(sigqueue_cachep, q);
291 static void flush_sigqueue(struct sigpending *queue)
295 sigemptyset(&queue->signal);
296 while (!list_empty(&queue->list)) {
297 q = list_entry(queue->list.next, struct sigqueue , list);
298 list_del_init(&q->list);
304 * Flush all pending signals for a task.
308 flush_signals(struct task_struct *t)
312 spin_lock_irqsave(&t->sighand->siglock, flags);
313 clear_tsk_thread_flag(t,TIF_SIGPENDING);
314 flush_sigqueue(&t->pending);
315 flush_sigqueue(&t->signal->shared_pending);
316 spin_unlock_irqrestore(&t->sighand->siglock, flags);
320 * This function expects the tasklist_lock write-locked.
322 void __exit_sighand(struct task_struct *tsk)
324 struct sighand_struct * sighand = tsk->sighand;
326 /* Ok, we're done with the signal handlers */
328 if (atomic_dec_and_test(&sighand->count))
329 kmem_cache_free(sighand_cachep, sighand);
332 void exit_sighand(struct task_struct *tsk)
334 write_lock_irq(&tasklist_lock);
336 write_unlock_irq(&tasklist_lock);
340 * This function expects the tasklist_lock write-locked.
342 void __exit_signal(struct task_struct *tsk)
344 struct signal_struct * sig = tsk->signal;
345 struct sighand_struct * sighand = tsk->sighand;
349 if (!atomic_read(&sig->count))
351 spin_lock(&sighand->siglock);
352 if (atomic_dec_and_test(&sig->count)) {
353 if (tsk == sig->curr_target)
354 sig->curr_target = next_thread(tsk);
356 spin_unlock(&sighand->siglock);
357 flush_sigqueue(&sig->shared_pending);
360 * If there is any task waiting for the group exit
363 if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count) {
364 wake_up_process(sig->group_exit_task);
365 sig->group_exit_task = NULL;
367 if (tsk == sig->curr_target)
368 sig->curr_target = next_thread(tsk);
370 spin_unlock(&sighand->siglock);
371 sig = NULL; /* Marker for below. */
373 clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
374 flush_sigqueue(&tsk->pending);
377 * We are cleaning up the signal_struct here. We delayed
378 * calling exit_itimers until after flush_sigqueue, just in
379 * case our thread-local pending queue contained a queued
380 * timer signal that would have been cleared in
381 * exit_itimers. When that called sigqueue_free, it would
382 * attempt to re-take the tasklist_lock and deadlock. This
383 * can never happen if we ensure that all queues the
384 * timer's signal might be queued on have been flushed
385 * first. The shared_pending queue, and our own pending
386 * queue are the only queues the timer could be on, since
387 * there are no other threads left in the group and timer
388 * signals are constrained to threads inside the group.
391 kmem_cache_free(signal_cachep, sig);
395 void exit_signal(struct task_struct *tsk)
397 write_lock_irq(&tasklist_lock);
399 write_unlock_irq(&tasklist_lock);
403 * Flush all handlers for a task.
407 flush_signal_handlers(struct task_struct *t, int force_default)
410 struct k_sigaction *ka = &t->sighand->action[0];
411 for (i = _NSIG ; i != 0 ; i--) {
412 if (force_default || ka->sa.sa_handler != SIG_IGN)
413 ka->sa.sa_handler = SIG_DFL;
415 sigemptyset(&ka->sa.sa_mask);
421 /* Notify the system that a driver wants to block all signals for this
422 * process, and wants to be notified if any signals at all were to be
423 * sent/acted upon. If the notifier routine returns non-zero, then the
424 * signal will be acted upon after all. If the notifier routine returns 0,
425 * then then signal will be blocked. Only one block per process is
426 * allowed. priv is a pointer to private data that the notifier routine
427 * can use to determine if the signal should be blocked or not. */
430 block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
434 spin_lock_irqsave(¤t->sighand->siglock, flags);
435 current->notifier_mask = mask;
436 current->notifier_data = priv;
437 current->notifier = notifier;
438 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
441 /* Notify the system that blocking has ended. */
444 unblock_all_signals(void)
448 spin_lock_irqsave(¤t->sighand->siglock, flags);
449 current->notifier = NULL;
450 current->notifier_data = NULL;
452 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
455 static inline int collect_signal(int sig, struct sigpending *list, siginfo_t *info)
457 struct sigqueue *q, *first = NULL;
458 int still_pending = 0;
460 if (unlikely(!sigismember(&list->signal, sig)))
464 * Collect the siginfo appropriate to this signal. Check if
465 * there is another siginfo for the same signal.
467 list_for_each_entry(q, &list->list, list) {
468 if (q->info.si_signo == sig) {
477 list_del_init(&first->list);
478 copy_siginfo(info, &first->info);
479 __sigqueue_free(first);
481 sigdelset(&list->signal, sig);
484 /* Ok, it wasn't in the queue. This must be
485 a fast-pathed signal or we must have been
486 out of queue space. So zero out the info.
488 sigdelset(&list->signal, sig);
489 info->si_signo = sig;
498 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
503 sig = next_signal(pending, mask);
505 if (current->notifier) {
506 if (sigismember(current->notifier_mask, sig)) {
507 if (!(current->notifier)(current->notifier_data)) {
508 clear_thread_flag(TIF_SIGPENDING);
514 if (!collect_signal(sig, pending, info))
524 * Dequeue a signal and return the element to the caller, which is
525 * expected to free it.
527 * All callers have to hold the siglock.
529 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
531 int signr = __dequeue_signal(&tsk->pending, mask, info);
533 signr = __dequeue_signal(&tsk->signal->shared_pending,
536 ((info->si_code & __SI_MASK) == __SI_TIMER) &&
537 info->si_sys_private){
538 do_schedule_next_timer(info);
544 * Tell a process that it has a new active signal..
546 * NOTE! we rely on the previous spin_lock to
547 * lock interrupts for us! We can only be called with
548 * "siglock" held, and the local interrupt must
549 * have been disabled when that got acquired!
551 * No need to set need_resched since signal event passing
552 * goes through ->blocked
554 void signal_wake_up(struct task_struct *t, int resume)
558 set_tsk_thread_flag(t, TIF_SIGPENDING);
561 * If resume is set, we want to wake it up in the TASK_STOPPED case.
562 * We don't check for TASK_STOPPED because there is a race with it
563 * executing another processor and just now entering stopped state.
564 * By calling wake_up_process any time resume is set, we ensure
565 * the process will wake up and handle its stop or death signal.
567 mask = TASK_INTERRUPTIBLE;
569 mask |= TASK_STOPPED;
570 if (!wake_up_state(t, mask))
575 * Remove signals in mask from the pending set and queue.
576 * Returns 1 if any signals were found.
578 * All callers must be holding the siglock.
580 static int rm_from_queue(unsigned long mask, struct sigpending *s)
582 struct sigqueue *q, *n;
584 if (!sigtestsetmask(&s->signal, mask))
587 sigdelsetmask(&s->signal, mask);
588 list_for_each_entry_safe(q, n, &s->list, list) {
589 if (q->info.si_signo < SIGRTMIN &&
590 (mask & sigmask(q->info.si_signo))) {
591 list_del_init(&q->list);
599 * Bad permissions for sending the signal
601 static int check_kill_permission(int sig, struct siginfo *info,
602 struct task_struct *t)
605 if (sig < 0 || sig > _NSIG)
608 if ((!info || ((unsigned long)info != 1 &&
609 (unsigned long)info != 2 && SI_FROMUSER(info)))
610 && ((sig != SIGCONT) ||
611 (current->signal->session != t->signal->session))
612 && (current->euid ^ t->suid) && (current->euid ^ t->uid)
613 && (current->uid ^ t->suid) && (current->uid ^ t->uid)
614 && !capable(CAP_KILL))
616 return security_task_kill(t, info, sig);
620 static void do_notify_parent_cldstop(struct task_struct *tsk,
621 struct task_struct *parent);
624 * Handle magic process-wide effects of stop/continue signals.
625 * Unlike the signal actions, these happen immediately at signal-generation
626 * time regardless of blocking, ignoring, or handling. This does the
627 * actual continuing for SIGCONT, but not the actual stopping for stop
628 * signals. The process stop is done as a signal action for SIG_DFL.
630 static void handle_stop_signal(int sig, struct task_struct *p)
632 struct task_struct *t;
634 if (sig_kernel_stop(sig)) {
636 * This is a stop signal. Remove SIGCONT from all queues.
638 rm_from_queue(sigmask(SIGCONT), &p->signal->shared_pending);
641 rm_from_queue(sigmask(SIGCONT), &t->pending);
644 } else if (sig == SIGCONT) {
646 * Remove all stop signals from all queues,
647 * and wake all threads.
649 if (unlikely(p->signal->group_stop_count > 0)) {
651 * There was a group stop in progress. We'll
652 * pretend it finished before we got here. We are
653 * obliged to report it to the parent: if the
654 * SIGSTOP happened "after" this SIGCONT, then it
655 * would have cleared this pending SIGCONT. If it
656 * happened "before" this SIGCONT, then the parent
657 * got the SIGCHLD about the stop finishing before
658 * the continue happened. We do the notification
659 * now, and it's as if the stop had finished and
660 * the SIGCHLD was pending on entry to this kill.
662 p->signal->group_stop_count = 0;
663 if (p->ptrace & PT_PTRACED)
664 do_notify_parent_cldstop(p, p->parent);
666 do_notify_parent_cldstop(
668 p->group_leader->real_parent);
670 rm_from_queue(SIG_KERNEL_STOP_MASK, &p->signal->shared_pending);
674 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
677 * If there is a handler for SIGCONT, we must make
678 * sure that no thread returns to user mode before
679 * we post the signal, in case it was the only
680 * thread eligible to run the signal handler--then
681 * it must not do anything between resuming and
682 * running the handler. With the TIF_SIGPENDING
683 * flag set, the thread will pause and acquire the
684 * siglock that we hold now and until we've queued
685 * the pending signal.
687 * Wake up the stopped thread _after_ setting
690 state = TASK_STOPPED;
691 if (sig_user_defined(t, SIGCONT) && !sigismember(&t->blocked, SIGCONT)) {
692 set_tsk_thread_flag(t, TIF_SIGPENDING);
693 state |= TASK_INTERRUPTIBLE;
695 wake_up_state(t, state);
702 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
703 struct sigpending *signals)
705 struct sigqueue * q = NULL;
709 * fast-pathed signals for kernel-internal things like SIGSTOP
712 if ((unsigned long)info == 2)
715 /* Real-time signals must be queued if sent by sigqueue, or
716 some other real-time mechanism. It is implementation
717 defined whether kill() does so. We attempt to do so, on
718 the principle of least surprise, but since kill is not
719 allowed to fail with EAGAIN when low on memory we just
720 make sure at least one signal gets delivered and don't
721 pass on the info struct. */
723 if (atomic_read(&t->user->sigpending) <
724 t->rlim[RLIMIT_SIGPENDING].rlim_cur)
725 q = kmem_cache_alloc(sigqueue_cachep, GFP_ATOMIC);
729 q->user = get_uid(t->user);
730 atomic_inc(&q->user->sigpending);
731 list_add_tail(&q->list, &signals->list);
732 switch ((unsigned long) info) {
734 q->info.si_signo = sig;
735 q->info.si_errno = 0;
736 q->info.si_code = SI_USER;
737 q->info.si_pid = current->pid;
738 q->info.si_uid = current->uid;
741 q->info.si_signo = sig;
742 q->info.si_errno = 0;
743 q->info.si_code = SI_KERNEL;
748 copy_siginfo(&q->info, info);
752 if (sig >= SIGRTMIN && info && (unsigned long)info != 1
753 && info->si_code != SI_USER)
755 * Queue overflow, abort. We may abort if the signal was rt
756 * and sent by user using something other than kill().
759 if (((unsigned long)info > 1) && (info->si_code == SI_TIMER))
761 * Set up a return to indicate that we dropped
764 ret = info->si_sys_private;
768 sigaddset(&signals->signal, sig);
772 #define LEGACY_QUEUE(sigptr, sig) \
773 (((sig) < SIGRTMIN) && sigismember(&(sigptr)->signal, (sig)))
777 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
781 if (!irqs_disabled())
784 if (!spin_is_locked(&t->sighand->siglock))
788 if (((unsigned long)info > 2) && (info->si_code == SI_TIMER))
790 * Set up a return to indicate that we dropped the signal.
792 ret = info->si_sys_private;
794 /* Short-circuit ignored signals. */
795 if (sig_ignored(t, sig))
798 /* Support queueing exactly one non-rt signal, so that we
799 can get more detailed information about the cause of
801 if (LEGACY_QUEUE(&t->pending, sig))
804 ret = send_signal(sig, info, t, &t->pending);
805 if (!ret && !sigismember(&t->blocked, sig))
806 signal_wake_up(t, sig == SIGKILL);
812 * Force a signal that the process can't ignore: if necessary
813 * we unblock the signal and change any SIG_IGN to SIG_DFL.
817 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
819 unsigned long int flags;
822 spin_lock_irqsave(&t->sighand->siglock, flags);
823 if (sigismember(&t->blocked, sig) || t->sighand->action[sig-1].sa.sa_handler == SIG_IGN) {
824 t->sighand->action[sig-1].sa.sa_handler = SIG_DFL;
825 sigdelset(&t->blocked, sig);
826 recalc_sigpending_tsk(t);
828 ret = specific_send_sig_info(sig, info, t);
829 spin_unlock_irqrestore(&t->sighand->siglock, flags);
835 force_sig_specific(int sig, struct task_struct *t)
837 unsigned long int flags;
839 spin_lock_irqsave(&t->sighand->siglock, flags);
840 if (t->sighand->action[sig-1].sa.sa_handler == SIG_IGN)
841 t->sighand->action[sig-1].sa.sa_handler = SIG_DFL;
842 sigdelset(&t->blocked, sig);
843 recalc_sigpending_tsk(t);
844 specific_send_sig_info(sig, (void *)2, t);
845 spin_unlock_irqrestore(&t->sighand->siglock, flags);
849 * Test if P wants to take SIG. After we've checked all threads with this,
850 * it's equivalent to finding no threads not blocking SIG. Any threads not
851 * blocking SIG were ruled out because they are not running and already
852 * have pending signals. Such threads will dequeue from the shared queue
853 * as soon as they're available, so putting the signal on the shared queue
854 * will be equivalent to sending it to one such thread.
856 #define wants_signal(sig, p, mask) \
857 (!sigismember(&(p)->blocked, sig) \
858 && !((p)->state & mask) \
859 && !((p)->flags & PF_EXITING) \
860 && (task_curr(p) || !signal_pending(p)))
864 __group_complete_signal(int sig, struct task_struct *p, unsigned int mask)
866 struct task_struct *t;
869 * Now find a thread we can wake up to take the signal off the queue.
871 * If the main thread wants the signal, it gets first crack.
872 * Probably the least surprising to the average bear.
874 if (wants_signal(sig, p, mask))
876 else if (thread_group_empty(p))
878 * There is just one thread and it does not need to be woken.
879 * It will dequeue unblocked signals before it runs again.
884 * Otherwise try to find a suitable thread.
886 t = p->signal->curr_target;
888 /* restart balancing at this thread */
889 t = p->signal->curr_target = p;
890 BUG_ON(t->tgid != p->tgid);
892 while (!wants_signal(sig, t, mask)) {
894 if (t == p->signal->curr_target)
896 * No thread needs to be woken.
897 * Any eligible threads will see
898 * the signal in the queue soon.
902 p->signal->curr_target = t;
906 * Found a killable thread. If the signal will be fatal,
907 * then start taking the whole group down immediately.
909 if (sig_fatal(p, sig) && !p->signal->group_exit &&
910 !sigismember(&t->real_blocked, sig) &&
911 (sig == SIGKILL || !(t->ptrace & PT_PTRACED))) {
913 * This signal will be fatal to the whole group.
915 if (!sig_kernel_coredump(sig)) {
917 * Start a group exit and wake everybody up.
918 * This way we don't have other threads
919 * running and doing things after a slower
920 * thread has the fatal signal pending.
922 p->signal->group_exit = 1;
923 p->signal->group_exit_code = sig;
924 p->signal->group_stop_count = 0;
927 sigaddset(&t->pending.signal, SIGKILL);
928 signal_wake_up(t, 1);
935 * There will be a core dump. We make all threads other
936 * than the chosen one go into a group stop so that nothing
937 * happens until it gets scheduled, takes the signal off
938 * the shared queue, and does the core dump. This is a
939 * little more complicated than strictly necessary, but it
940 * keeps the signal state that winds up in the core dump
941 * unchanged from the death state, e.g. which thread had
942 * the core-dump signal unblocked.
944 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
945 rm_from_queue(SIG_KERNEL_STOP_MASK, &p->signal->shared_pending);
946 p->signal->group_stop_count = 0;
947 p->signal->group_exit_task = t;
950 p->signal->group_stop_count++;
951 signal_wake_up(t, 0);
954 wake_up_process(p->signal->group_exit_task);
959 * The signal is already in the shared-pending queue.
960 * Tell the chosen thread to wake up and dequeue it.
962 signal_wake_up(t, sig == SIGKILL);
967 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
973 if (!spin_is_locked(&p->sighand->siglock))
976 handle_stop_signal(sig, p);
978 if (((unsigned long)info > 2) && (info->si_code == SI_TIMER))
980 * Set up a return to indicate that we dropped the signal.
982 ret = info->si_sys_private;
984 /* Short-circuit ignored signals. */
985 if (sig_ignored(p, sig))
988 if (LEGACY_QUEUE(&p->signal->shared_pending, sig))
989 /* This is a non-RT signal and we already have one queued. */
993 * Don't bother zombies and stopped tasks (but
994 * SIGKILL will punch through stopped state)
996 mask = TASK_DEAD | TASK_ZOMBIE;
998 mask |= TASK_STOPPED;
1001 * Put this signal on the shared-pending queue, or fail with EAGAIN.
1002 * We always use the shared queue for process-wide signals,
1003 * to avoid several races.
1005 ret = send_signal(sig, info, p, &p->signal->shared_pending);
1009 __group_complete_signal(sig, p, mask);
1014 * Nuke all other threads in the group.
1016 void zap_other_threads(struct task_struct *p)
1018 struct task_struct *t;
1020 p->signal->group_stop_count = 0;
1022 if (thread_group_empty(p))
1025 for (t = next_thread(p); t != p; t = next_thread(t)) {
1027 * Don't bother with already dead threads
1029 if (t->state & (TASK_ZOMBIE|TASK_DEAD))
1033 * We don't want to notify the parent, since we are
1034 * killed as part of a thread group due to another
1035 * thread doing an execve() or similar. So set the
1036 * exit signal to -1 to allow immediate reaping of
1037 * the process. But don't detach the thread group
1040 if (t != p->group_leader)
1041 t->exit_signal = -1;
1043 sigaddset(&t->pending.signal, SIGKILL);
1044 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
1045 signal_wake_up(t, 1);
1050 * Must be called with the tasklist_lock held for reading!
1052 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1054 unsigned long flags;
1057 if (!vx_check(vx_task_xid(p), VX_ADMIN|VX_WATCH|VX_IDENT))
1060 ret = check_kill_permission(sig, info, p);
1061 if (!ret && sig && p->sighand) {
1062 spin_lock_irqsave(&p->sighand->siglock, flags);
1063 ret = __group_send_sig_info(sig, info, p);
1064 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1071 * kill_pg_info() sends a signal to a process group: this is what the tty
1072 * control characters do (^C, ^Z etc)
1075 int __kill_pg_info(int sig, struct siginfo *info, pid_t pgrp)
1077 struct task_struct *p;
1078 struct list_head *l;
1080 int retval, success;
1087 for_each_task_pid(pgrp, PIDTYPE_PGID, p, l, pid) {
1088 int err = group_send_sig_info(sig, info, p);
1092 return success ? 0 : retval;
1096 kill_pg_info(int sig, struct siginfo *info, pid_t pgrp)
1100 read_lock(&tasklist_lock);
1101 retval = __kill_pg_info(sig, info, pgrp);
1102 read_unlock(&tasklist_lock);
1108 * kill_sl_info() sends a signal to the session leader: this is used
1109 * to send SIGHUP to the controlling process of a terminal when
1110 * the connection is lost.
1115 kill_sl_info(int sig, struct siginfo *info, pid_t sid)
1117 int err, retval = -EINVAL;
1119 struct list_head *l;
1120 struct task_struct *p;
1126 read_lock(&tasklist_lock);
1127 for_each_task_pid(sid, PIDTYPE_SID, p, l, pid) {
1128 if (!p->signal->leader)
1130 err = group_send_sig_info(sig, info, p);
1134 read_unlock(&tasklist_lock);
1140 kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1143 struct task_struct *p;
1145 read_lock(&tasklist_lock);
1146 p = find_task_by_pid(pid);
1149 error = group_send_sig_info(sig, info, p);
1150 read_unlock(&tasklist_lock);
1156 * kill_something_info() interprets pid in interesting ways just like kill(2).
1158 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1159 * is probably wrong. Should make it like BSD or SYSV.
1162 static int kill_something_info(int sig, struct siginfo *info, int pid)
1165 return kill_pg_info(sig, info, process_group(current));
1166 } else if (pid == -1) {
1167 int retval = 0, count = 0;
1168 struct task_struct * p;
1170 read_lock(&tasklist_lock);
1171 for_each_process(p) {
1172 if (p->pid > 1 && p->tgid != current->tgid) {
1173 int err = group_send_sig_info(sig, info, p);
1179 read_unlock(&tasklist_lock);
1180 return count ? retval : -ESRCH;
1181 } else if (pid < 0) {
1182 return kill_pg_info(sig, info, -pid);
1184 return kill_proc_info(sig, info, pid);
1189 * These are for backward compatibility with the rest of the kernel source.
1193 * These two are the most common entry points. They send a signal
1194 * just to the specific thread.
1197 send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1200 unsigned long flags;
1203 * Make sure legacy kernel users don't send in bad values
1204 * (normal paths check this in check_kill_permission).
1206 if (sig < 0 || sig > _NSIG)
1210 * We need the tasklist lock even for the specific
1211 * thread case (when we don't need to follow the group
1212 * lists) in order to avoid races with "p->sighand"
1213 * going away or changing from under us.
1215 read_lock(&tasklist_lock);
1216 spin_lock_irqsave(&p->sighand->siglock, flags);
1217 ret = specific_send_sig_info(sig, info, p);
1218 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1219 read_unlock(&tasklist_lock);
1224 send_sig(int sig, struct task_struct *p, int priv)
1226 return send_sig_info(sig, (void*)(long)(priv != 0), p);
1230 * This is the entry point for "process-wide" signals.
1231 * They will go to an appropriate thread in the thread group.
1234 send_group_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1237 read_lock(&tasklist_lock);
1238 ret = group_send_sig_info(sig, info, p);
1239 read_unlock(&tasklist_lock);
1244 force_sig(int sig, struct task_struct *p)
1246 force_sig_info(sig, (void*)1L, p);
1250 kill_pg(pid_t pgrp, int sig, int priv)
1252 return kill_pg_info(sig, (void *)(long)(priv != 0), pgrp);
1256 kill_sl(pid_t sess, int sig, int priv)
1258 return kill_sl_info(sig, (void *)(long)(priv != 0), sess);
1262 kill_proc(pid_t pid, int sig, int priv)
1264 return kill_proc_info(sig, (void *)(long)(priv != 0), pid);
1268 * These functions support sending signals using preallocated sigqueue
1269 * structures. This is needed "because realtime applications cannot
1270 * afford to lose notifications of asynchronous events, like timer
1271 * expirations or I/O completions". In the case of Posix Timers
1272 * we allocate the sigqueue structure from the timer_create. If this
1273 * allocation fails we are able to report the failure to the application
1274 * with an EAGAIN error.
1277 struct sigqueue *sigqueue_alloc(void)
1281 if ((q = __sigqueue_alloc()))
1282 q->flags |= SIGQUEUE_PREALLOC;
1286 void sigqueue_free(struct sigqueue *q)
1288 unsigned long flags;
1289 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1291 * If the signal is still pending remove it from the
1294 if (unlikely(!list_empty(&q->list))) {
1295 read_lock(&tasklist_lock);
1296 spin_lock_irqsave(q->lock, flags);
1297 if (!list_empty(&q->list))
1298 list_del_init(&q->list);
1299 spin_unlock_irqrestore(q->lock, flags);
1300 read_unlock(&tasklist_lock);
1302 q->flags &= ~SIGQUEUE_PREALLOC;
1307 send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
1309 unsigned long flags;
1313 * We need the tasklist lock even for the specific
1314 * thread case (when we don't need to follow the group
1315 * lists) in order to avoid races with "p->sighand"
1316 * going away or changing from under us.
1318 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1319 read_lock(&tasklist_lock);
1320 spin_lock_irqsave(&p->sighand->siglock, flags);
1322 if (unlikely(!list_empty(&q->list))) {
1324 * If an SI_TIMER entry is already queue just increment
1325 * the overrun count.
1327 if (q->info.si_code != SI_TIMER)
1329 q->info.si_overrun++;
1332 /* Short-circuit ignored signals. */
1333 if (sig_ignored(p, sig)) {
1338 q->lock = &p->sighand->siglock;
1339 list_add_tail(&q->list, &p->pending.list);
1340 sigaddset(&p->pending.signal, sig);
1341 if (!sigismember(&p->blocked, sig))
1342 signal_wake_up(p, sig == SIGKILL);
1345 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1346 read_unlock(&tasklist_lock);
1351 send_group_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
1353 unsigned long flags;
1357 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1358 read_lock(&tasklist_lock);
1359 spin_lock_irqsave(&p->sighand->siglock, flags);
1360 handle_stop_signal(sig, p);
1362 /* Short-circuit ignored signals. */
1363 if (sig_ignored(p, sig)) {
1368 if (unlikely(!list_empty(&q->list))) {
1370 * If an SI_TIMER entry is already queue just increment
1371 * the overrun count. Other uses should not try to
1372 * send the signal multiple times.
1374 if (q->info.si_code != SI_TIMER)
1376 q->info.si_overrun++;
1380 * Don't bother zombies and stopped tasks (but
1381 * SIGKILL will punch through stopped state)
1383 mask = TASK_DEAD | TASK_ZOMBIE;
1385 mask |= TASK_STOPPED;
1388 * Put this signal on the shared-pending queue.
1389 * We always use the shared queue for process-wide signals,
1390 * to avoid several races.
1392 q->lock = &p->sighand->siglock;
1393 list_add_tail(&q->list, &p->signal->shared_pending.list);
1394 sigaddset(&p->signal->shared_pending.signal, sig);
1396 __group_complete_signal(sig, p, mask);
1398 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1399 read_unlock(&tasklist_lock);
1404 * Joy. Or not. Pthread wants us to wake up every thread
1405 * in our parent group.
1407 static void __wake_up_parent(struct task_struct *p,
1408 struct task_struct *parent)
1410 struct task_struct *tsk = parent;
1413 * Fortunately this is not necessary for thread groups:
1415 if (p->tgid == tsk->tgid) {
1416 wake_up_interruptible_sync(&tsk->wait_chldexit);
1421 wake_up_interruptible_sync(&tsk->wait_chldexit);
1422 tsk = next_thread(tsk);
1423 if (tsk->signal != parent->signal)
1425 } while (tsk != parent);
1429 * Let a parent know about a status change of a child.
1432 void do_notify_parent(struct task_struct *tsk, int sig)
1434 struct siginfo info;
1435 unsigned long flags;
1437 struct sighand_struct *psig;
1442 BUG_ON(tsk->group_leader != tsk && tsk->group_leader->state != TASK_ZOMBIE && !tsk->ptrace);
1443 BUG_ON(tsk->group_leader == tsk && !thread_group_empty(tsk) && !tsk->ptrace);
1445 info.si_signo = sig;
1447 info.si_pid = tsk->pid;
1448 info.si_uid = tsk->uid;
1450 /* FIXME: find out whether or not this is supposed to be c*time. */
1451 info.si_utime = tsk->utime;
1452 info.si_stime = tsk->stime;
1454 status = tsk->exit_code & 0x7f;
1455 why = SI_KERNEL; /* shouldn't happen */
1456 switch (tsk->state) {
1458 /* FIXME -- can we deduce CLD_TRAPPED or CLD_CONTINUED? */
1459 if (tsk->ptrace & PT_PTRACED)
1466 if (tsk->exit_code & 0x80)
1468 else if (tsk->exit_code & 0x7f)
1472 status = tsk->exit_code >> 8;
1477 info.si_status = status;
1479 psig = tsk->parent->sighand;
1480 spin_lock_irqsave(&psig->siglock, flags);
1481 if (sig == SIGCHLD && tsk->state != TASK_STOPPED &&
1482 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1483 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1485 * We are exiting and our parent doesn't care. POSIX.1
1486 * defines special semantics for setting SIGCHLD to SIG_IGN
1487 * or setting the SA_NOCLDWAIT flag: we should be reaped
1488 * automatically and not left for our parent's wait4 call.
1489 * Rather than having the parent do it as a magic kind of
1490 * signal handler, we just set this to tell do_exit that we
1491 * can be cleaned up without becoming a zombie. Note that
1492 * we still call __wake_up_parent in this case, because a
1493 * blocked sys_wait4 might now return -ECHILD.
1495 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1496 * is implementation-defined: we do (if you don't want
1497 * it, just use SIG_IGN instead).
1499 tsk->exit_signal = -1;
1500 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1503 if (sig > 0 && sig <= _NSIG)
1504 __group_send_sig_info(sig, &info, tsk->parent);
1505 __wake_up_parent(tsk, tsk->parent);
1506 spin_unlock_irqrestore(&psig->siglock, flags);
1511 * We need the tasklist lock because it's the only
1512 * thing that protects out "parent" pointer.
1514 * exit.c calls "do_notify_parent()" directly, because
1515 * it already has the tasklist lock.
1518 notify_parent(struct task_struct *tsk, int sig)
1521 read_lock(&tasklist_lock);
1522 do_notify_parent(tsk, sig);
1523 read_unlock(&tasklist_lock);
1528 do_notify_parent_cldstop(struct task_struct *tsk, struct task_struct *parent)
1530 struct siginfo info;
1531 unsigned long flags;
1532 struct sighand_struct *sighand;
1534 info.si_signo = SIGCHLD;
1536 info.si_pid = tsk->pid;
1537 info.si_uid = tsk->uid;
1539 /* FIXME: find out whether or not this is supposed to be c*time. */
1540 info.si_utime = tsk->utime;
1541 info.si_stime = tsk->stime;
1543 info.si_status = tsk->exit_code & 0x7f;
1544 info.si_code = CLD_STOPPED;
1546 sighand = parent->sighand;
1547 spin_lock_irqsave(&sighand->siglock, flags);
1548 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1549 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1550 __group_send_sig_info(SIGCHLD, &info, parent);
1552 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1554 __wake_up_parent(tsk, parent);
1555 spin_unlock_irqrestore(&sighand->siglock, flags);
1559 #ifndef HAVE_ARCH_GET_SIGNAL_TO_DELIVER
1562 finish_stop(int stop_count)
1565 * If there are no other threads in the group, or if there is
1566 * a group stop in progress and we are the last to stop,
1567 * report to the parent. When ptraced, every thread reports itself.
1569 if (stop_count < 0 || (current->ptrace & PT_PTRACED)) {
1570 read_lock(&tasklist_lock);
1571 do_notify_parent_cldstop(current, current->parent);
1572 read_unlock(&tasklist_lock);
1574 else if (stop_count == 0) {
1575 read_lock(&tasklist_lock);
1576 do_notify_parent_cldstop(current->group_leader,
1577 current->group_leader->real_parent);
1578 read_unlock(&tasklist_lock);
1583 * Now we don't run again until continued.
1585 current->exit_code = 0;
1589 * This performs the stopping for SIGSTOP and other stop signals.
1590 * We have to stop all threads in the thread group.
1593 do_signal_stop(int signr)
1595 struct signal_struct *sig = current->signal;
1596 struct sighand_struct *sighand = current->sighand;
1597 int stop_count = -1;
1599 /* spin_lock_irq(&sighand->siglock) is now done in caller */
1601 if (sig->group_stop_count > 0) {
1603 * There is a group stop in progress. We don't need to
1604 * start another one.
1606 signr = sig->group_exit_code;
1607 stop_count = --sig->group_stop_count;
1608 current->exit_code = signr;
1609 set_current_state(TASK_STOPPED);
1610 spin_unlock_irq(&sighand->siglock);
1612 else if (thread_group_empty(current)) {
1614 * Lock must be held through transition to stopped state.
1616 current->exit_code = signr;
1617 set_current_state(TASK_STOPPED);
1618 spin_unlock_irq(&sighand->siglock);
1622 * There is no group stop already in progress.
1623 * We must initiate one now, but that requires
1624 * dropping siglock to get both the tasklist lock
1625 * and siglock again in the proper order. Note that
1626 * this allows an intervening SIGCONT to be posted.
1627 * We need to check for that and bail out if necessary.
1629 struct task_struct *t;
1631 spin_unlock_irq(&sighand->siglock);
1633 /* signals can be posted during this window */
1635 read_lock(&tasklist_lock);
1636 spin_lock_irq(&sighand->siglock);
1638 if (unlikely(sig->group_exit)) {
1640 * There is a group exit in progress now.
1641 * We'll just ignore the stop and process the
1642 * associated fatal signal.
1644 spin_unlock_irq(&sighand->siglock);
1645 read_unlock(&tasklist_lock);
1649 if (unlikely(sig_avoid_stop_race())) {
1651 * Either a SIGCONT or a SIGKILL signal was
1652 * posted in the siglock-not-held window.
1654 spin_unlock_irq(&sighand->siglock);
1655 read_unlock(&tasklist_lock);
1659 if (sig->group_stop_count == 0) {
1660 sig->group_exit_code = signr;
1662 for (t = next_thread(current); t != current;
1665 * Setting state to TASK_STOPPED for a group
1666 * stop is always done with the siglock held,
1667 * so this check has no races.
1669 if (t->state < TASK_STOPPED) {
1671 signal_wake_up(t, 0);
1673 sig->group_stop_count = stop_count;
1676 /* A race with another thread while unlocked. */
1677 signr = sig->group_exit_code;
1678 stop_count = --sig->group_stop_count;
1681 current->exit_code = signr;
1682 set_current_state(TASK_STOPPED);
1684 spin_unlock_irq(&sighand->siglock);
1685 read_unlock(&tasklist_lock);
1688 finish_stop(stop_count);
1692 * Do appropriate magic when group_stop_count > 0.
1693 * We return nonzero if we stopped, after releasing the siglock.
1694 * We return zero if we still hold the siglock and should look
1695 * for another signal without checking group_stop_count again.
1697 static inline int handle_group_stop(void)
1701 if (current->signal->group_exit_task == current) {
1703 * Group stop is so we can do a core dump,
1704 * We are the initiating thread, so get on with it.
1706 current->signal->group_exit_task = NULL;
1710 if (current->signal->group_exit)
1712 * Group stop is so another thread can do a core dump,
1713 * or else we are racing against a death signal.
1714 * Just punt the stop so we can get the next signal.
1719 * There is a group stop in progress. We stop
1720 * without any associated signal being in our queue.
1722 stop_count = --current->signal->group_stop_count;
1723 current->exit_code = current->signal->group_exit_code;
1724 set_current_state(TASK_STOPPED);
1725 spin_unlock_irq(¤t->sighand->siglock);
1726 finish_stop(stop_count);
1730 int get_signal_to_deliver(siginfo_t *info, struct pt_regs *regs, void *cookie)
1732 sigset_t *mask = ¤t->blocked;
1736 spin_lock_irq(¤t->sighand->siglock);
1738 struct k_sigaction *ka;
1740 if (unlikely(current->signal->group_stop_count > 0) &&
1741 handle_group_stop())
1744 signr = dequeue_signal(current, mask, info);
1747 break; /* will return 0 */
1749 if ((current->ptrace & PT_PTRACED) && signr != SIGKILL) {
1750 ptrace_signal_deliver(regs, cookie);
1753 * If there is a group stop in progress,
1754 * we must participate in the bookkeeping.
1756 if (current->signal->group_stop_count > 0)
1757 --current->signal->group_stop_count;
1759 /* Let the debugger run. */
1760 current->exit_code = signr;
1761 current->last_siginfo = info;
1762 set_current_state(TASK_STOPPED);
1763 spin_unlock_irq(¤t->sighand->siglock);
1764 notify_parent(current, SIGCHLD);
1767 current->last_siginfo = NULL;
1769 /* We're back. Did the debugger cancel the sig? */
1770 spin_lock_irq(¤t->sighand->siglock);
1771 signr = current->exit_code;
1775 current->exit_code = 0;
1777 /* Update the siginfo structure if the signal has
1778 changed. If the debugger wanted something
1779 specific in the siginfo structure then it should
1780 have updated *info via PTRACE_SETSIGINFO. */
1781 if (signr != info->si_signo) {
1782 info->si_signo = signr;
1784 info->si_code = SI_USER;
1785 info->si_pid = current->parent->pid;
1786 info->si_uid = current->parent->uid;
1789 /* If the (new) signal is now blocked, requeue it. */
1790 if (sigismember(¤t->blocked, signr)) {
1791 specific_send_sig_info(signr, info, current);
1796 ka = ¤t->sighand->action[signr-1];
1797 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
1799 if (ka->sa.sa_handler != SIG_DFL) /* Run the handler. */
1800 break; /* will return non-zero "signr" value */
1803 * Now we are doing the default action for this signal.
1805 if (sig_kernel_ignore(signr)) /* Default is nothing. */
1808 /* Init gets no signals it doesn't want. */
1809 if (current->pid == 1)
1812 if (sig_kernel_stop(signr)) {
1814 * The default action is to stop all threads in
1815 * the thread group. The job control signals
1816 * do nothing in an orphaned pgrp, but SIGSTOP
1817 * always works. Note that siglock needs to be
1818 * dropped during the call to is_orphaned_pgrp()
1819 * because of lock ordering with tasklist_lock.
1820 * This allows an intervening SIGCONT to be posted.
1821 * We need to check for that and bail out if necessary.
1823 if (signr == SIGSTOP) {
1824 do_signal_stop(signr); /* releases siglock */
1827 spin_unlock_irq(¤t->sighand->siglock);
1829 /* signals can be posted during this window */
1831 if (is_orphaned_pgrp(process_group(current)))
1834 spin_lock_irq(¤t->sighand->siglock);
1835 if (unlikely(sig_avoid_stop_race())) {
1837 * Either a SIGCONT or a SIGKILL signal was
1838 * posted in the siglock-not-held window.
1843 do_signal_stop(signr); /* releases siglock */
1847 spin_unlock_irq(¤t->sighand->siglock);
1850 * Anything else is fatal, maybe with a core dump.
1852 current->flags |= PF_SIGNALED;
1853 if (sig_kernel_coredump(signr) &&
1854 do_coredump((long)signr, signr, regs)) {
1856 * That killed all other threads in the group and
1857 * synchronized with their demise, so there can't
1858 * be any more left to kill now. The group_exit
1859 * flags are set by do_coredump. Note that
1860 * thread_group_empty won't always be true yet,
1861 * because those threads were blocked in __exit_mm
1862 * and we just let them go to finish dying.
1864 const int code = signr | 0x80;
1865 BUG_ON(!current->signal->group_exit);
1866 BUG_ON(current->signal->group_exit_code != code);
1872 * Death signals, no core dump.
1874 do_group_exit(signr);
1877 spin_unlock_irq(¤t->sighand->siglock);
1883 EXPORT_SYMBOL(recalc_sigpending);
1884 EXPORT_SYMBOL_GPL(dequeue_signal);
1885 EXPORT_SYMBOL(flush_signals);
1886 EXPORT_SYMBOL(force_sig);
1887 EXPORT_SYMBOL(force_sig_info);
1888 EXPORT_SYMBOL(kill_pg);
1889 EXPORT_SYMBOL(kill_pg_info);
1890 EXPORT_SYMBOL(kill_proc);
1891 EXPORT_SYMBOL(kill_proc_info);
1892 EXPORT_SYMBOL(kill_sl);
1893 EXPORT_SYMBOL(kill_sl_info);
1894 EXPORT_SYMBOL(notify_parent);
1895 EXPORT_SYMBOL(send_sig);
1896 EXPORT_SYMBOL(send_sig_info);
1897 EXPORT_SYMBOL(send_group_sig_info);
1898 EXPORT_SYMBOL(sigqueue_alloc);
1899 EXPORT_SYMBOL(sigqueue_free);
1900 EXPORT_SYMBOL(send_sigqueue);
1901 EXPORT_SYMBOL(send_group_sigqueue);
1902 EXPORT_SYMBOL(sigprocmask);
1903 EXPORT_SYMBOL(block_all_signals);
1904 EXPORT_SYMBOL(unblock_all_signals);
1908 * System call entry points.
1911 asmlinkage long sys_restart_syscall(void)
1913 struct restart_block *restart = ¤t_thread_info()->restart_block;
1914 return restart->fn(restart);
1917 long do_no_restart_syscall(struct restart_block *param)
1923 * We don't need to get the kernel lock - this is all local to this
1924 * particular thread.. (and that's good, because this is _heavily_
1925 * used by various programs)
1929 * This is also useful for kernel threads that want to temporarily
1930 * (or permanently) block certain signals.
1932 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
1933 * interface happily blocks "unblockable" signals like SIGKILL
1936 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
1941 spin_lock_irq(¤t->sighand->siglock);
1942 old_block = current->blocked;
1946 sigorsets(¤t->blocked, ¤t->blocked, set);
1949 signandsets(¤t->blocked, ¤t->blocked, set);
1952 current->blocked = *set;
1957 recalc_sigpending();
1958 spin_unlock_irq(¤t->sighand->siglock);
1960 *oldset = old_block;
1965 sys_rt_sigprocmask(int how, sigset_t __user *set, sigset_t __user *oset, size_t sigsetsize)
1967 int error = -EINVAL;
1968 sigset_t old_set, new_set;
1970 /* XXX: Don't preclude handling different sized sigset_t's. */
1971 if (sigsetsize != sizeof(sigset_t))
1976 if (copy_from_user(&new_set, set, sizeof(*set)))
1978 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
1980 error = sigprocmask(how, &new_set, &old_set);
1986 spin_lock_irq(¤t->sighand->siglock);
1987 old_set = current->blocked;
1988 spin_unlock_irq(¤t->sighand->siglock);
1992 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2000 long do_sigpending(void __user *set, unsigned long sigsetsize)
2002 long error = -EINVAL;
2005 if (sigsetsize > sizeof(sigset_t))
2008 spin_lock_irq(¤t->sighand->siglock);
2009 sigorsets(&pending, ¤t->pending.signal,
2010 ¤t->signal->shared_pending.signal);
2011 spin_unlock_irq(¤t->sighand->siglock);
2013 /* Outside the lock because only this thread touches it. */
2014 sigandsets(&pending, ¤t->blocked, &pending);
2017 if (!copy_to_user(set, &pending, sigsetsize))
2025 sys_rt_sigpending(sigset_t __user *set, size_t sigsetsize)
2027 return do_sigpending(set, sigsetsize);
2030 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2032 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2036 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2038 if (from->si_code < 0)
2039 return __copy_to_user(to, from, sizeof(siginfo_t))
2042 * If you change siginfo_t structure, please be sure
2043 * this code is fixed accordingly.
2044 * It should never copy any pad contained in the structure
2045 * to avoid security leaks, but must copy the generic
2046 * 3 ints plus the relevant union member.
2048 err = __put_user(from->si_signo, &to->si_signo);
2049 err |= __put_user(from->si_errno, &to->si_errno);
2050 err |= __put_user((short)from->si_code, &to->si_code);
2051 switch (from->si_code & __SI_MASK) {
2053 err |= __put_user(from->si_pid, &to->si_pid);
2054 err |= __put_user(from->si_uid, &to->si_uid);
2057 err |= __put_user(from->si_tid, &to->si_tid);
2058 err |= __put_user(from->si_overrun, &to->si_overrun);
2059 err |= __put_user(from->si_ptr, &to->si_ptr);
2062 err |= __put_user(from->si_band, &to->si_band);
2063 err |= __put_user(from->si_fd, &to->si_fd);
2066 err |= __put_user(from->si_addr, &to->si_addr);
2067 #ifdef __ARCH_SI_TRAPNO
2068 err |= __put_user(from->si_trapno, &to->si_trapno);
2072 err |= __put_user(from->si_pid, &to->si_pid);
2073 err |= __put_user(from->si_uid, &to->si_uid);
2074 err |= __put_user(from->si_status, &to->si_status);
2075 err |= __put_user(from->si_utime, &to->si_utime);
2076 err |= __put_user(from->si_stime, &to->si_stime);
2078 case __SI_RT: /* This is not generated by the kernel as of now. */
2079 case __SI_MESGQ: /* But this is */
2080 err |= __put_user(from->si_pid, &to->si_pid);
2081 err |= __put_user(from->si_uid, &to->si_uid);
2082 err |= __put_user(from->si_ptr, &to->si_ptr);
2084 default: /* this is just in case for now ... */
2085 err |= __put_user(from->si_pid, &to->si_pid);
2086 err |= __put_user(from->si_uid, &to->si_uid);
2095 sys_rt_sigtimedwait(const sigset_t __user *uthese,
2096 siginfo_t __user *uinfo,
2097 const struct timespec __user *uts,
2106 /* XXX: Don't preclude handling different sized sigset_t's. */
2107 if (sigsetsize != sizeof(sigset_t))
2110 if (copy_from_user(&these, uthese, sizeof(these)))
2114 * Invert the set of allowed signals to get those we
2117 sigdelsetmask(&these, sigmask(SIGKILL)|sigmask(SIGSTOP));
2121 if (copy_from_user(&ts, uts, sizeof(ts)))
2123 if (ts.tv_nsec >= 1000000000L || ts.tv_nsec < 0
2128 spin_lock_irq(¤t->sighand->siglock);
2129 sig = dequeue_signal(current, &these, &info);
2131 timeout = MAX_SCHEDULE_TIMEOUT;
2133 timeout = (timespec_to_jiffies(&ts)
2134 + (ts.tv_sec || ts.tv_nsec));
2137 /* None ready -- temporarily unblock those we're
2138 * interested while we are sleeping in so that we'll
2139 * be awakened when they arrive. */
2140 current->real_blocked = current->blocked;
2141 sigandsets(¤t->blocked, ¤t->blocked, &these);
2142 recalc_sigpending();
2143 spin_unlock_irq(¤t->sighand->siglock);
2145 current->state = TASK_INTERRUPTIBLE;
2146 timeout = schedule_timeout(timeout);
2148 spin_lock_irq(¤t->sighand->siglock);
2149 sig = dequeue_signal(current, &these, &info);
2150 current->blocked = current->real_blocked;
2151 siginitset(¤t->real_blocked, 0);
2152 recalc_sigpending();
2155 spin_unlock_irq(¤t->sighand->siglock);
2160 if (copy_siginfo_to_user(uinfo, &info))
2173 sys_kill(int pid, int sig)
2175 struct siginfo info;
2177 info.si_signo = sig;
2179 info.si_code = SI_USER;
2180 info.si_pid = current->tgid;
2181 info.si_uid = current->uid;
2183 return kill_something_info(sig, &info, pid);
2187 * sys_tgkill - send signal to one specific thread
2188 * @tgid: the thread group ID of the thread
2189 * @pid: the PID of the thread
2190 * @sig: signal to be sent
2192 * This syscall also checks the tgid and returns -ESRCH even if the PID
2193 * exists but it's not belonging to the target process anymore. This
2194 * method solves the problem of threads exiting and PIDs getting reused.
2196 asmlinkage long sys_tgkill(int tgid, int pid, int sig)
2198 struct siginfo info;
2200 struct task_struct *p;
2202 /* This is only valid for single tasks */
2203 if (pid <= 0 || tgid <= 0)
2206 info.si_signo = sig;
2208 info.si_code = SI_TKILL;
2209 info.si_pid = current->tgid;
2210 info.si_uid = current->uid;
2212 read_lock(&tasklist_lock);
2213 p = find_task_by_pid(pid);
2215 if (p && (p->tgid == tgid)) {
2216 error = check_kill_permission(sig, &info, p);
2218 * The null signal is a permissions and process existence
2219 * probe. No signal is actually delivered.
2221 if (!error && sig && p->sighand) {
2222 spin_lock_irq(&p->sighand->siglock);
2223 handle_stop_signal(sig, p);
2224 error = specific_send_sig_info(sig, &info, p);
2225 spin_unlock_irq(&p->sighand->siglock);
2228 read_unlock(&tasklist_lock);
2233 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2236 sys_tkill(int pid, int sig)
2238 struct siginfo info;
2240 struct task_struct *p;
2242 /* This is only valid for single tasks */
2246 info.si_signo = sig;
2248 info.si_code = SI_TKILL;
2249 info.si_pid = current->tgid;
2250 info.si_uid = current->uid;
2252 read_lock(&tasklist_lock);
2253 p = find_task_by_pid(pid);
2256 error = check_kill_permission(sig, &info, p);
2258 * The null signal is a permissions and process existence
2259 * probe. No signal is actually delivered.
2261 if (!error && sig && p->sighand) {
2262 spin_lock_irq(&p->sighand->siglock);
2263 handle_stop_signal(sig, p);
2264 error = specific_send_sig_info(sig, &info, p);
2265 spin_unlock_irq(&p->sighand->siglock);
2268 read_unlock(&tasklist_lock);
2273 sys_rt_sigqueueinfo(int pid, int sig, siginfo_t __user *uinfo)
2277 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2280 /* Not even root can pretend to send signals from the kernel.
2281 Nor can they impersonate a kill(), which adds source info. */
2282 if (info.si_code >= 0)
2284 info.si_signo = sig;
2286 /* POSIX.1b doesn't mention process groups. */
2287 return kill_proc_info(sig, &info, pid);
2291 do_sigaction(int sig, const struct k_sigaction *act, struct k_sigaction *oact)
2293 struct k_sigaction *k;
2295 if (sig < 1 || sig > _NSIG || (act && sig_kernel_only(sig)))
2298 k = ¤t->sighand->action[sig-1];
2300 spin_lock_irq(¤t->sighand->siglock);
2301 if (signal_pending(current)) {
2303 * If there might be a fatal signal pending on multiple
2304 * threads, make sure we take it before changing the action.
2306 spin_unlock_irq(¤t->sighand->siglock);
2307 return -ERESTARTNOINTR;
2316 * "Setting a signal action to SIG_IGN for a signal that is
2317 * pending shall cause the pending signal to be discarded,
2318 * whether or not it is blocked."
2320 * "Setting a signal action to SIG_DFL for a signal that is
2321 * pending and whose default action is to ignore the signal
2322 * (for example, SIGCHLD), shall cause the pending signal to
2323 * be discarded, whether or not it is blocked"
2325 if (act->sa.sa_handler == SIG_IGN ||
2326 (act->sa.sa_handler == SIG_DFL &&
2327 sig_kernel_ignore(sig))) {
2329 * This is a fairly rare case, so we only take the
2330 * tasklist_lock once we're sure we'll need it.
2331 * Now we must do this little unlock and relock
2332 * dance to maintain the lock hierarchy.
2334 struct task_struct *t = current;
2335 spin_unlock_irq(&t->sighand->siglock);
2336 read_lock(&tasklist_lock);
2337 spin_lock_irq(&t->sighand->siglock);
2339 sigdelsetmask(&k->sa.sa_mask,
2340 sigmask(SIGKILL) | sigmask(SIGSTOP));
2341 rm_from_queue(sigmask(sig), &t->signal->shared_pending);
2343 rm_from_queue(sigmask(sig), &t->pending);
2344 recalc_sigpending_tsk(t);
2346 } while (t != current);
2347 spin_unlock_irq(¤t->sighand->siglock);
2348 read_unlock(&tasklist_lock);
2353 sigdelsetmask(&k->sa.sa_mask,
2354 sigmask(SIGKILL) | sigmask(SIGSTOP));
2357 spin_unlock_irq(¤t->sighand->siglock);
2362 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
2368 oss.ss_sp = (void __user *) current->sas_ss_sp;
2369 oss.ss_size = current->sas_ss_size;
2370 oss.ss_flags = sas_ss_flags(sp);
2379 if (verify_area(VERIFY_READ, uss, sizeof(*uss))
2380 || __get_user(ss_sp, &uss->ss_sp)
2381 || __get_user(ss_flags, &uss->ss_flags)
2382 || __get_user(ss_size, &uss->ss_size))
2386 if (on_sig_stack(sp))
2392 * Note - this code used to test ss_flags incorrectly
2393 * old code may have been written using ss_flags==0
2394 * to mean ss_flags==SS_ONSTACK (as this was the only
2395 * way that worked) - this fix preserves that older
2398 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
2401 if (ss_flags == SS_DISABLE) {
2406 if (ss_size < MINSIGSTKSZ)
2410 current->sas_ss_sp = (unsigned long) ss_sp;
2411 current->sas_ss_size = ss_size;
2416 if (copy_to_user(uoss, &oss, sizeof(oss)))
2425 #ifdef __ARCH_WANT_SYS_SIGPENDING
2428 sys_sigpending(old_sigset_t __user *set)
2430 return do_sigpending(set, sizeof(*set));
2435 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
2436 /* Some platforms have their own version with special arguments others
2437 support only sys_rt_sigprocmask. */
2440 sys_sigprocmask(int how, old_sigset_t __user *set, old_sigset_t __user *oset)
2443 old_sigset_t old_set, new_set;
2447 if (copy_from_user(&new_set, set, sizeof(*set)))
2449 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
2451 spin_lock_irq(¤t->sighand->siglock);
2452 old_set = current->blocked.sig[0];
2460 sigaddsetmask(¤t->blocked, new_set);
2463 sigdelsetmask(¤t->blocked, new_set);
2466 current->blocked.sig[0] = new_set;
2470 recalc_sigpending();
2471 spin_unlock_irq(¤t->sighand->siglock);
2477 old_set = current->blocked.sig[0];
2480 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2487 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
2489 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
2491 sys_rt_sigaction(int sig,
2492 const struct sigaction __user *act,
2493 struct sigaction __user *oact,
2496 struct k_sigaction new_sa, old_sa;
2499 /* XXX: Don't preclude handling different sized sigset_t's. */
2500 if (sigsetsize != sizeof(sigset_t))
2504 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
2508 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
2511 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
2517 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
2519 #ifdef __ARCH_WANT_SYS_SGETMASK
2522 * For backwards compatibility. Functionality superseded by sigprocmask.
2528 return current->blocked.sig[0];
2532 sys_ssetmask(int newmask)
2536 spin_lock_irq(¤t->sighand->siglock);
2537 old = current->blocked.sig[0];
2539 siginitset(¤t->blocked, newmask & ~(sigmask(SIGKILL)|
2541 recalc_sigpending();
2542 spin_unlock_irq(¤t->sighand->siglock);
2546 #endif /* __ARCH_WANT_SGETMASK */
2548 #ifdef __ARCH_WANT_SYS_SIGNAL
2550 * For backwards compatibility. Functionality superseded by sigaction.
2552 asmlinkage unsigned long
2553 sys_signal(int sig, __sighandler_t handler)
2555 struct k_sigaction new_sa, old_sa;
2558 new_sa.sa.sa_handler = handler;
2559 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
2561 ret = do_sigaction(sig, &new_sa, &old_sa);
2563 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
2565 #endif /* __ARCH_WANT_SYS_SIGNAL */
2567 #ifdef __ARCH_WANT_SYS_PAUSE
2572 current->state = TASK_INTERRUPTIBLE;
2574 return -ERESTARTNOHAND;
2579 void __init signals_init(void)
2582 kmem_cache_create("sigqueue",
2583 sizeof(struct sigqueue),
2584 __alignof__(struct sigqueue),
2585 SLAB_PANIC, NULL, NULL);