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);
420 EXPORT_SYMBOL_GPL(flush_signal_handlers);
422 /* Notify the system that a driver wants to block all signals for this
423 * process, and wants to be notified if any signals at all were to be
424 * sent/acted upon. If the notifier routine returns non-zero, then the
425 * signal will be acted upon after all. If the notifier routine returns 0,
426 * then then signal will be blocked. Only one block per process is
427 * allowed. priv is a pointer to private data that the notifier routine
428 * can use to determine if the signal should be blocked or not. */
431 block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
435 spin_lock_irqsave(¤t->sighand->siglock, flags);
436 current->notifier_mask = mask;
437 current->notifier_data = priv;
438 current->notifier = notifier;
439 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
442 /* Notify the system that blocking has ended. */
445 unblock_all_signals(void)
449 spin_lock_irqsave(¤t->sighand->siglock, flags);
450 current->notifier = NULL;
451 current->notifier_data = NULL;
453 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
456 static inline int collect_signal(int sig, struct sigpending *list, siginfo_t *info)
458 struct sigqueue *q, *first = NULL;
459 int still_pending = 0;
461 if (unlikely(!sigismember(&list->signal, sig)))
465 * Collect the siginfo appropriate to this signal. Check if
466 * there is another siginfo for the same signal.
468 list_for_each_entry(q, &list->list, list) {
469 if (q->info.si_signo == sig) {
478 list_del_init(&first->list);
479 copy_siginfo(info, &first->info);
480 __sigqueue_free(first);
482 sigdelset(&list->signal, sig);
485 /* Ok, it wasn't in the queue. This must be
486 a fast-pathed signal or we must have been
487 out of queue space. So zero out the info.
489 sigdelset(&list->signal, sig);
490 info->si_signo = sig;
499 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
504 sig = next_signal(pending, mask);
506 if (current->notifier) {
507 if (sigismember(current->notifier_mask, sig)) {
508 if (!(current->notifier)(current->notifier_data)) {
509 clear_thread_flag(TIF_SIGPENDING);
515 if (!collect_signal(sig, pending, info))
525 * Dequeue a signal and return the element to the caller, which is
526 * expected to free it.
528 * All callers have to hold the siglock.
530 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
532 int signr = __dequeue_signal(&tsk->pending, mask, info);
534 signr = __dequeue_signal(&tsk->signal->shared_pending,
537 ((info->si_code & __SI_MASK) == __SI_TIMER) &&
538 info->si_sys_private){
539 do_schedule_next_timer(info);
545 * Tell a process that it has a new active signal..
547 * NOTE! we rely on the previous spin_lock to
548 * lock interrupts for us! We can only be called with
549 * "siglock" held, and the local interrupt must
550 * have been disabled when that got acquired!
552 * No need to set need_resched since signal event passing
553 * goes through ->blocked
555 void signal_wake_up(struct task_struct *t, int resume)
559 set_tsk_thread_flag(t, TIF_SIGPENDING);
562 * If resume is set, we want to wake it up in the TASK_STOPPED case.
563 * We don't check for TASK_STOPPED because there is a race with it
564 * executing another processor and just now entering stopped state.
565 * By calling wake_up_process any time resume is set, we ensure
566 * the process will wake up and handle its stop or death signal.
568 mask = TASK_INTERRUPTIBLE;
570 mask |= TASK_STOPPED;
571 if (!wake_up_state(t, mask))
576 * Remove signals in mask from the pending set and queue.
577 * Returns 1 if any signals were found.
579 * All callers must be holding the siglock.
581 static int rm_from_queue(unsigned long mask, struct sigpending *s)
583 struct sigqueue *q, *n;
585 if (!sigtestsetmask(&s->signal, mask))
588 sigdelsetmask(&s->signal, mask);
589 list_for_each_entry_safe(q, n, &s->list, list) {
590 if (q->info.si_signo < SIGRTMIN &&
591 (mask & sigmask(q->info.si_signo))) {
592 list_del_init(&q->list);
600 * Bad permissions for sending the signal
602 static int check_kill_permission(int sig, struct siginfo *info,
603 struct task_struct *t)
606 if (sig < 0 || sig > _NSIG)
609 if ((!info || ((unsigned long)info != 1 &&
610 (unsigned long)info != 2 && SI_FROMUSER(info)))
611 && ((sig != SIGCONT) ||
612 (current->signal->session != t->signal->session))
613 && (current->euid ^ t->suid) && (current->euid ^ t->uid)
614 && (current->uid ^ t->suid) && (current->uid ^ t->uid)
615 && !capable(CAP_KILL))
617 return security_task_kill(t, info, sig);
621 static void do_notify_parent_cldstop(struct task_struct *tsk,
622 struct task_struct *parent);
625 * Handle magic process-wide effects of stop/continue signals.
626 * Unlike the signal actions, these happen immediately at signal-generation
627 * time regardless of blocking, ignoring, or handling. This does the
628 * actual continuing for SIGCONT, but not the actual stopping for stop
629 * signals. The process stop is done as a signal action for SIG_DFL.
631 static void handle_stop_signal(int sig, struct task_struct *p)
633 struct task_struct *t;
635 if (sig_kernel_stop(sig)) {
637 * This is a stop signal. Remove SIGCONT from all queues.
639 rm_from_queue(sigmask(SIGCONT), &p->signal->shared_pending);
642 rm_from_queue(sigmask(SIGCONT), &t->pending);
645 } else if (sig == SIGCONT) {
647 * Remove all stop signals from all queues,
648 * and wake all threads.
650 if (unlikely(p->signal->group_stop_count > 0)) {
652 * There was a group stop in progress. We'll
653 * pretend it finished before we got here. We are
654 * obliged to report it to the parent: if the
655 * SIGSTOP happened "after" this SIGCONT, then it
656 * would have cleared this pending SIGCONT. If it
657 * happened "before" this SIGCONT, then the parent
658 * got the SIGCHLD about the stop finishing before
659 * the continue happened. We do the notification
660 * now, and it's as if the stop had finished and
661 * the SIGCHLD was pending on entry to this kill.
663 p->signal->group_stop_count = 0;
664 if (p->ptrace & PT_PTRACED)
665 do_notify_parent_cldstop(p, p->parent);
667 do_notify_parent_cldstop(
669 p->group_leader->real_parent);
671 rm_from_queue(SIG_KERNEL_STOP_MASK, &p->signal->shared_pending);
675 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
678 * If there is a handler for SIGCONT, we must make
679 * sure that no thread returns to user mode before
680 * we post the signal, in case it was the only
681 * thread eligible to run the signal handler--then
682 * it must not do anything between resuming and
683 * running the handler. With the TIF_SIGPENDING
684 * flag set, the thread will pause and acquire the
685 * siglock that we hold now and until we've queued
686 * the pending signal.
688 * Wake up the stopped thread _after_ setting
691 state = TASK_STOPPED;
692 if (sig_user_defined(t, SIGCONT) && !sigismember(&t->blocked, SIGCONT)) {
693 set_tsk_thread_flag(t, TIF_SIGPENDING);
694 state |= TASK_INTERRUPTIBLE;
696 wake_up_state(t, state);
703 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
704 struct sigpending *signals)
706 struct sigqueue * q = NULL;
710 * fast-pathed signals for kernel-internal things like SIGSTOP
713 if ((unsigned long)info == 2)
716 /* Real-time signals must be queued if sent by sigqueue, or
717 some other real-time mechanism. It is implementation
718 defined whether kill() does so. We attempt to do so, on
719 the principle of least surprise, but since kill is not
720 allowed to fail with EAGAIN when low on memory we just
721 make sure at least one signal gets delivered and don't
722 pass on the info struct. */
724 if (atomic_read(&t->user->sigpending) <
725 t->rlim[RLIMIT_SIGPENDING].rlim_cur)
726 q = kmem_cache_alloc(sigqueue_cachep, GFP_ATOMIC);
730 q->user = get_uid(t->user);
731 atomic_inc(&q->user->sigpending);
732 list_add_tail(&q->list, &signals->list);
733 switch ((unsigned long) info) {
735 q->info.si_signo = sig;
736 q->info.si_errno = 0;
737 q->info.si_code = SI_USER;
738 q->info.si_pid = current->pid;
739 q->info.si_uid = current->uid;
742 q->info.si_signo = sig;
743 q->info.si_errno = 0;
744 q->info.si_code = SI_KERNEL;
749 copy_siginfo(&q->info, info);
753 if (sig >= SIGRTMIN && info && (unsigned long)info != 1
754 && info->si_code != SI_USER)
756 * Queue overflow, abort. We may abort if the signal was rt
757 * and sent by user using something other than kill().
760 if (((unsigned long)info > 1) && (info->si_code == SI_TIMER))
762 * Set up a return to indicate that we dropped
765 ret = info->si_sys_private;
769 sigaddset(&signals->signal, sig);
773 #define LEGACY_QUEUE(sigptr, sig) \
774 (((sig) < SIGRTMIN) && sigismember(&(sigptr)->signal, (sig)))
778 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
782 if (!irqs_disabled())
785 if (!spin_is_locked(&t->sighand->siglock))
789 if (((unsigned long)info > 2) && (info->si_code == SI_TIMER))
791 * Set up a return to indicate that we dropped the signal.
793 ret = info->si_sys_private;
795 /* Short-circuit ignored signals. */
796 if (sig_ignored(t, sig))
799 /* Support queueing exactly one non-rt signal, so that we
800 can get more detailed information about the cause of
802 if (LEGACY_QUEUE(&t->pending, sig))
805 ret = send_signal(sig, info, t, &t->pending);
806 if (!ret && !sigismember(&t->blocked, sig))
807 signal_wake_up(t, sig == SIGKILL);
813 * Force a signal that the process can't ignore: if necessary
814 * we unblock the signal and change any SIG_IGN to SIG_DFL.
818 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
820 unsigned long int flags;
823 spin_lock_irqsave(&t->sighand->siglock, flags);
824 if (sigismember(&t->blocked, sig) || t->sighand->action[sig-1].sa.sa_handler == SIG_IGN) {
825 t->sighand->action[sig-1].sa.sa_handler = SIG_DFL;
826 sigdelset(&t->blocked, sig);
827 recalc_sigpending_tsk(t);
829 ret = specific_send_sig_info(sig, info, t);
830 spin_unlock_irqrestore(&t->sighand->siglock, flags);
836 force_sig_specific(int sig, struct task_struct *t)
838 unsigned long int flags;
840 spin_lock_irqsave(&t->sighand->siglock, flags);
841 if (t->sighand->action[sig-1].sa.sa_handler == SIG_IGN)
842 t->sighand->action[sig-1].sa.sa_handler = SIG_DFL;
843 sigdelset(&t->blocked, sig);
844 recalc_sigpending_tsk(t);
845 specific_send_sig_info(sig, (void *)2, t);
846 spin_unlock_irqrestore(&t->sighand->siglock, flags);
850 * Test if P wants to take SIG. After we've checked all threads with this,
851 * it's equivalent to finding no threads not blocking SIG. Any threads not
852 * blocking SIG were ruled out because they are not running and already
853 * have pending signals. Such threads will dequeue from the shared queue
854 * as soon as they're available, so putting the signal on the shared queue
855 * will be equivalent to sending it to one such thread.
857 #define wants_signal(sig, p, mask) \
858 (!sigismember(&(p)->blocked, sig) \
859 && !((p)->state & mask) \
860 && !((p)->flags & PF_EXITING) \
861 && (task_curr(p) || !signal_pending(p)))
865 __group_complete_signal(int sig, struct task_struct *p, unsigned int mask)
867 struct task_struct *t;
870 * Now find a thread we can wake up to take the signal off the queue.
872 * If the main thread wants the signal, it gets first crack.
873 * Probably the least surprising to the average bear.
875 if (wants_signal(sig, p, mask))
877 else if (thread_group_empty(p))
879 * There is just one thread and it does not need to be woken.
880 * It will dequeue unblocked signals before it runs again.
885 * Otherwise try to find a suitable thread.
887 t = p->signal->curr_target;
889 /* restart balancing at this thread */
890 t = p->signal->curr_target = p;
891 BUG_ON(t->tgid != p->tgid);
893 while (!wants_signal(sig, t, mask)) {
895 if (t == p->signal->curr_target)
897 * No thread needs to be woken.
898 * Any eligible threads will see
899 * the signal in the queue soon.
903 p->signal->curr_target = t;
907 * Found a killable thread. If the signal will be fatal,
908 * then start taking the whole group down immediately.
910 if (sig_fatal(p, sig) && !p->signal->group_exit &&
911 !sigismember(&t->real_blocked, sig) &&
912 (sig == SIGKILL || !(t->ptrace & PT_PTRACED))) {
914 * This signal will be fatal to the whole group.
916 if (!sig_kernel_coredump(sig)) {
918 * Start a group exit and wake everybody up.
919 * This way we don't have other threads
920 * running and doing things after a slower
921 * thread has the fatal signal pending.
923 p->signal->group_exit = 1;
924 p->signal->group_exit_code = sig;
925 p->signal->group_stop_count = 0;
928 sigaddset(&t->pending.signal, SIGKILL);
929 signal_wake_up(t, 1);
936 * There will be a core dump. We make all threads other
937 * than the chosen one go into a group stop so that nothing
938 * happens until it gets scheduled, takes the signal off
939 * the shared queue, and does the core dump. This is a
940 * little more complicated than strictly necessary, but it
941 * keeps the signal state that winds up in the core dump
942 * unchanged from the death state, e.g. which thread had
943 * the core-dump signal unblocked.
945 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
946 rm_from_queue(SIG_KERNEL_STOP_MASK, &p->signal->shared_pending);
947 p->signal->group_stop_count = 0;
948 p->signal->group_exit_task = t;
951 p->signal->group_stop_count++;
952 signal_wake_up(t, 0);
955 wake_up_process(p->signal->group_exit_task);
960 * The signal is already in the shared-pending queue.
961 * Tell the chosen thread to wake up and dequeue it.
963 signal_wake_up(t, sig == SIGKILL);
968 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
974 if (!spin_is_locked(&p->sighand->siglock))
977 handle_stop_signal(sig, p);
979 if (((unsigned long)info > 2) && (info->si_code == SI_TIMER))
981 * Set up a return to indicate that we dropped the signal.
983 ret = info->si_sys_private;
985 /* Short-circuit ignored signals. */
986 if (sig_ignored(p, sig))
989 if (LEGACY_QUEUE(&p->signal->shared_pending, sig))
990 /* This is a non-RT signal and we already have one queued. */
994 * Don't bother zombies and stopped tasks (but
995 * SIGKILL will punch through stopped state)
997 mask = TASK_DEAD | TASK_ZOMBIE;
999 mask |= TASK_STOPPED;
1002 * Put this signal on the shared-pending queue, or fail with EAGAIN.
1003 * We always use the shared queue for process-wide signals,
1004 * to avoid several races.
1006 ret = send_signal(sig, info, p, &p->signal->shared_pending);
1010 __group_complete_signal(sig, p, mask);
1015 * Nuke all other threads in the group.
1017 void zap_other_threads(struct task_struct *p)
1019 struct task_struct *t;
1021 p->signal->group_stop_count = 0;
1023 if (thread_group_empty(p))
1026 for (t = next_thread(p); t != p; t = next_thread(t)) {
1028 * Don't bother with already dead threads
1030 if (t->state & (TASK_ZOMBIE|TASK_DEAD))
1034 * We don't want to notify the parent, since we are
1035 * killed as part of a thread group due to another
1036 * thread doing an execve() or similar. So set the
1037 * exit signal to -1 to allow immediate reaping of
1038 * the process. But don't detach the thread group
1041 if (t != p->group_leader)
1042 t->exit_signal = -1;
1044 sigaddset(&t->pending.signal, SIGKILL);
1045 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
1046 signal_wake_up(t, 1);
1051 * Must be called with the tasklist_lock held for reading!
1053 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1055 unsigned long flags;
1058 if (!vx_check(vx_task_xid(p), VX_ADMIN|VX_WATCH|VX_IDENT))
1061 ret = check_kill_permission(sig, info, p);
1062 if (!ret && sig && p->sighand) {
1063 spin_lock_irqsave(&p->sighand->siglock, flags);
1064 ret = __group_send_sig_info(sig, info, p);
1065 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1072 * kill_pg_info() sends a signal to a process group: this is what the tty
1073 * control characters do (^C, ^Z etc)
1076 int __kill_pg_info(int sig, struct siginfo *info, pid_t pgrp)
1078 struct task_struct *p;
1079 struct list_head *l;
1081 int retval, success;
1088 for_each_task_pid(pgrp, PIDTYPE_PGID, p, l, pid) {
1089 int err = group_send_sig_info(sig, info, p);
1093 return success ? 0 : retval;
1097 kill_pg_info(int sig, struct siginfo *info, pid_t pgrp)
1101 read_lock(&tasklist_lock);
1102 retval = __kill_pg_info(sig, info, pgrp);
1103 read_unlock(&tasklist_lock);
1109 * kill_sl_info() sends a signal to the session leader: this is used
1110 * to send SIGHUP to the controlling process of a terminal when
1111 * the connection is lost.
1116 kill_sl_info(int sig, struct siginfo *info, pid_t sid)
1118 int err, retval = -EINVAL;
1120 struct list_head *l;
1121 struct task_struct *p;
1127 read_lock(&tasklist_lock);
1128 for_each_task_pid(sid, PIDTYPE_SID, p, l, pid) {
1129 if (!p->signal->leader)
1131 err = group_send_sig_info(sig, info, p);
1135 read_unlock(&tasklist_lock);
1141 kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1144 struct task_struct *p;
1146 read_lock(&tasklist_lock);
1147 p = find_task_by_pid(pid);
1150 error = group_send_sig_info(sig, info, p);
1151 read_unlock(&tasklist_lock);
1157 * kill_something_info() interprets pid in interesting ways just like kill(2).
1159 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1160 * is probably wrong. Should make it like BSD or SYSV.
1163 static int kill_something_info(int sig, struct siginfo *info, int pid)
1166 return kill_pg_info(sig, info, process_group(current));
1167 } else if (pid == -1) {
1168 int retval = 0, count = 0;
1169 struct task_struct * p;
1171 read_lock(&tasklist_lock);
1172 for_each_process(p) {
1173 if (p->pid > 1 && p->tgid != current->tgid) {
1174 int err = group_send_sig_info(sig, info, p);
1180 read_unlock(&tasklist_lock);
1181 return count ? retval : -ESRCH;
1182 } else if (pid < 0) {
1183 return kill_pg_info(sig, info, -pid);
1185 return kill_proc_info(sig, info, pid);
1190 * These are for backward compatibility with the rest of the kernel source.
1194 * These two are the most common entry points. They send a signal
1195 * just to the specific thread.
1198 send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1201 unsigned long flags;
1204 * Make sure legacy kernel users don't send in bad values
1205 * (normal paths check this in check_kill_permission).
1207 if (sig < 0 || sig > _NSIG)
1211 * We need the tasklist lock even for the specific
1212 * thread case (when we don't need to follow the group
1213 * lists) in order to avoid races with "p->sighand"
1214 * going away or changing from under us.
1216 read_lock(&tasklist_lock);
1217 spin_lock_irqsave(&p->sighand->siglock, flags);
1218 ret = specific_send_sig_info(sig, info, p);
1219 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1220 read_unlock(&tasklist_lock);
1225 send_sig(int sig, struct task_struct *p, int priv)
1227 return send_sig_info(sig, (void*)(long)(priv != 0), p);
1231 * This is the entry point for "process-wide" signals.
1232 * They will go to an appropriate thread in the thread group.
1235 send_group_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1238 read_lock(&tasklist_lock);
1239 ret = group_send_sig_info(sig, info, p);
1240 read_unlock(&tasklist_lock);
1245 force_sig(int sig, struct task_struct *p)
1247 force_sig_info(sig, (void*)1L, p);
1251 kill_pg(pid_t pgrp, int sig, int priv)
1253 return kill_pg_info(sig, (void *)(long)(priv != 0), pgrp);
1257 kill_sl(pid_t sess, int sig, int priv)
1259 return kill_sl_info(sig, (void *)(long)(priv != 0), sess);
1263 kill_proc(pid_t pid, int sig, int priv)
1265 return kill_proc_info(sig, (void *)(long)(priv != 0), pid);
1269 * These functions support sending signals using preallocated sigqueue
1270 * structures. This is needed "because realtime applications cannot
1271 * afford to lose notifications of asynchronous events, like timer
1272 * expirations or I/O completions". In the case of Posix Timers
1273 * we allocate the sigqueue structure from the timer_create. If this
1274 * allocation fails we are able to report the failure to the application
1275 * with an EAGAIN error.
1278 struct sigqueue *sigqueue_alloc(void)
1282 if ((q = __sigqueue_alloc()))
1283 q->flags |= SIGQUEUE_PREALLOC;
1287 void sigqueue_free(struct sigqueue *q)
1289 unsigned long flags;
1290 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1292 * If the signal is still pending remove it from the
1295 if (unlikely(!list_empty(&q->list))) {
1296 read_lock(&tasklist_lock);
1297 spin_lock_irqsave(q->lock, flags);
1298 if (!list_empty(&q->list))
1299 list_del_init(&q->list);
1300 spin_unlock_irqrestore(q->lock, flags);
1301 read_unlock(&tasklist_lock);
1303 q->flags &= ~SIGQUEUE_PREALLOC;
1308 send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
1310 unsigned long flags;
1314 * We need the tasklist lock even for the specific
1315 * thread case (when we don't need to follow the group
1316 * lists) in order to avoid races with "p->sighand"
1317 * going away or changing from under us.
1319 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1320 read_lock(&tasklist_lock);
1321 spin_lock_irqsave(&p->sighand->siglock, flags);
1323 if (unlikely(!list_empty(&q->list))) {
1325 * If an SI_TIMER entry is already queue just increment
1326 * the overrun count.
1328 if (q->info.si_code != SI_TIMER)
1330 q->info.si_overrun++;
1333 /* Short-circuit ignored signals. */
1334 if (sig_ignored(p, sig)) {
1339 q->lock = &p->sighand->siglock;
1340 list_add_tail(&q->list, &p->pending.list);
1341 sigaddset(&p->pending.signal, sig);
1342 if (!sigismember(&p->blocked, sig))
1343 signal_wake_up(p, sig == SIGKILL);
1346 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1347 read_unlock(&tasklist_lock);
1352 send_group_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
1354 unsigned long flags;
1358 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1359 read_lock(&tasklist_lock);
1360 spin_lock_irqsave(&p->sighand->siglock, flags);
1361 handle_stop_signal(sig, p);
1363 /* Short-circuit ignored signals. */
1364 if (sig_ignored(p, sig)) {
1369 if (unlikely(!list_empty(&q->list))) {
1371 * If an SI_TIMER entry is already queue just increment
1372 * the overrun count. Other uses should not try to
1373 * send the signal multiple times.
1375 if (q->info.si_code != SI_TIMER)
1377 q->info.si_overrun++;
1381 * Don't bother zombies and stopped tasks (but
1382 * SIGKILL will punch through stopped state)
1384 mask = TASK_DEAD | TASK_ZOMBIE;
1386 mask |= TASK_STOPPED;
1389 * Put this signal on the shared-pending queue.
1390 * We always use the shared queue for process-wide signals,
1391 * to avoid several races.
1393 q->lock = &p->sighand->siglock;
1394 list_add_tail(&q->list, &p->signal->shared_pending.list);
1395 sigaddset(&p->signal->shared_pending.signal, sig);
1397 __group_complete_signal(sig, p, mask);
1399 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1400 read_unlock(&tasklist_lock);
1405 * Joy. Or not. Pthread wants us to wake up every thread
1406 * in our parent group.
1408 static void __wake_up_parent(struct task_struct *p,
1409 struct task_struct *parent)
1411 struct task_struct *tsk = parent;
1414 * Fortunately this is not necessary for thread groups:
1416 if (p->tgid == tsk->tgid) {
1417 wake_up_interruptible_sync(&tsk->wait_chldexit);
1422 wake_up_interruptible_sync(&tsk->wait_chldexit);
1423 tsk = next_thread(tsk);
1424 if (tsk->signal != parent->signal)
1426 } while (tsk != parent);
1430 * Let a parent know about a status change of a child.
1433 void do_notify_parent(struct task_struct *tsk, int sig)
1435 struct siginfo info;
1436 unsigned long flags;
1438 struct sighand_struct *psig;
1443 BUG_ON(tsk->group_leader != tsk && tsk->group_leader->state != TASK_ZOMBIE && !tsk->ptrace);
1444 BUG_ON(tsk->group_leader == tsk && !thread_group_empty(tsk) && !tsk->ptrace);
1446 info.si_signo = sig;
1448 info.si_pid = tsk->pid;
1449 info.si_uid = tsk->uid;
1451 /* FIXME: find out whether or not this is supposed to be c*time. */
1452 info.si_utime = tsk->utime;
1453 info.si_stime = tsk->stime;
1455 status = tsk->exit_code & 0x7f;
1456 why = SI_KERNEL; /* shouldn't happen */
1457 switch (tsk->state) {
1459 /* FIXME -- can we deduce CLD_TRAPPED or CLD_CONTINUED? */
1460 if (tsk->ptrace & PT_PTRACED)
1467 if (tsk->exit_code & 0x80)
1469 else if (tsk->exit_code & 0x7f)
1473 status = tsk->exit_code >> 8;
1478 info.si_status = status;
1480 psig = tsk->parent->sighand;
1481 spin_lock_irqsave(&psig->siglock, flags);
1482 if (sig == SIGCHLD && tsk->state != TASK_STOPPED &&
1483 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1484 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1486 * We are exiting and our parent doesn't care. POSIX.1
1487 * defines special semantics for setting SIGCHLD to SIG_IGN
1488 * or setting the SA_NOCLDWAIT flag: we should be reaped
1489 * automatically and not left for our parent's wait4 call.
1490 * Rather than having the parent do it as a magic kind of
1491 * signal handler, we just set this to tell do_exit that we
1492 * can be cleaned up without becoming a zombie. Note that
1493 * we still call __wake_up_parent in this case, because a
1494 * blocked sys_wait4 might now return -ECHILD.
1496 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1497 * is implementation-defined: we do (if you don't want
1498 * it, just use SIG_IGN instead).
1500 tsk->exit_signal = -1;
1501 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1504 if (sig > 0 && sig <= _NSIG)
1505 __group_send_sig_info(sig, &info, tsk->parent);
1506 __wake_up_parent(tsk, tsk->parent);
1507 spin_unlock_irqrestore(&psig->siglock, flags);
1512 * We need the tasklist lock because it's the only
1513 * thing that protects out "parent" pointer.
1515 * exit.c calls "do_notify_parent()" directly, because
1516 * it already has the tasklist lock.
1519 notify_parent(struct task_struct *tsk, int sig)
1522 read_lock(&tasklist_lock);
1523 do_notify_parent(tsk, sig);
1524 read_unlock(&tasklist_lock);
1529 do_notify_parent_cldstop(struct task_struct *tsk, struct task_struct *parent)
1531 struct siginfo info;
1532 unsigned long flags;
1533 struct sighand_struct *sighand;
1535 info.si_signo = SIGCHLD;
1537 info.si_pid = tsk->pid;
1538 info.si_uid = tsk->uid;
1540 /* FIXME: find out whether or not this is supposed to be c*time. */
1541 info.si_utime = tsk->utime;
1542 info.si_stime = tsk->stime;
1544 info.si_status = tsk->exit_code & 0x7f;
1545 info.si_code = CLD_STOPPED;
1547 sighand = parent->sighand;
1548 spin_lock_irqsave(&sighand->siglock, flags);
1549 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1550 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1551 __group_send_sig_info(SIGCHLD, &info, parent);
1553 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1555 __wake_up_parent(tsk, parent);
1556 spin_unlock_irqrestore(&sighand->siglock, flags);
1559 int print_fatal_signals = 0;
1561 static void print_fatal_signal(struct pt_regs *regs, int signr)
1565 printk("%s/%d: potentially unexpected fatal signal %d.\n",
1566 current->comm, current->pid, signr);
1569 printk("code at %08lx: ", regs->eip);
1570 for (i = 0; i < 16; i++) {
1571 __get_user(insn, (unsigned char *)(regs->eip + i));
1572 printk("%02x ", insn);
1579 static int __init setup_print_fatal_signals(char *str)
1581 get_option (&str, &print_fatal_signals);
1586 __setup("print-fatal-signals=", setup_print_fatal_signals);
1588 #ifndef HAVE_ARCH_GET_SIGNAL_TO_DELIVER
1591 finish_stop(int stop_count)
1594 * If there are no other threads in the group, or if there is
1595 * a group stop in progress and we are the last to stop,
1596 * report to the parent. When ptraced, every thread reports itself.
1598 if (stop_count < 0 || (current->ptrace & PT_PTRACED)) {
1599 read_lock(&tasklist_lock);
1600 do_notify_parent_cldstop(current, current->parent);
1601 read_unlock(&tasklist_lock);
1603 else if (stop_count == 0) {
1604 read_lock(&tasklist_lock);
1605 do_notify_parent_cldstop(current->group_leader,
1606 current->group_leader->real_parent);
1607 read_unlock(&tasklist_lock);
1612 * Now we don't run again until continued.
1614 current->exit_code = 0;
1618 * This performs the stopping for SIGSTOP and other stop signals.
1619 * We have to stop all threads in the thread group.
1622 do_signal_stop(int signr)
1624 struct signal_struct *sig = current->signal;
1625 struct sighand_struct *sighand = current->sighand;
1626 int stop_count = -1;
1628 /* spin_lock_irq(&sighand->siglock) is now done in caller */
1630 if (sig->group_stop_count > 0) {
1632 * There is a group stop in progress. We don't need to
1633 * start another one.
1635 signr = sig->group_exit_code;
1636 stop_count = --sig->group_stop_count;
1637 current->exit_code = signr;
1638 set_current_state(TASK_STOPPED);
1639 spin_unlock_irq(&sighand->siglock);
1641 else if (thread_group_empty(current)) {
1643 * Lock must be held through transition to stopped state.
1645 current->exit_code = signr;
1646 set_current_state(TASK_STOPPED);
1647 spin_unlock_irq(&sighand->siglock);
1651 * There is no group stop already in progress.
1652 * We must initiate one now, but that requires
1653 * dropping siglock to get both the tasklist lock
1654 * and siglock again in the proper order. Note that
1655 * this allows an intervening SIGCONT to be posted.
1656 * We need to check for that and bail out if necessary.
1658 struct task_struct *t;
1660 spin_unlock_irq(&sighand->siglock);
1662 /* signals can be posted during this window */
1664 read_lock(&tasklist_lock);
1665 spin_lock_irq(&sighand->siglock);
1667 if (unlikely(sig->group_exit)) {
1669 * There is a group exit in progress now.
1670 * We'll just ignore the stop and process the
1671 * associated fatal signal.
1673 spin_unlock_irq(&sighand->siglock);
1674 read_unlock(&tasklist_lock);
1678 if (unlikely(sig_avoid_stop_race())) {
1680 * Either a SIGCONT or a SIGKILL signal was
1681 * posted in the siglock-not-held window.
1683 spin_unlock_irq(&sighand->siglock);
1684 read_unlock(&tasklist_lock);
1688 if (sig->group_stop_count == 0) {
1689 sig->group_exit_code = signr;
1691 for (t = next_thread(current); t != current;
1694 * Setting state to TASK_STOPPED for a group
1695 * stop is always done with the siglock held,
1696 * so this check has no races.
1698 if (t->state < TASK_STOPPED) {
1700 signal_wake_up(t, 0);
1702 sig->group_stop_count = stop_count;
1705 /* A race with another thread while unlocked. */
1706 signr = sig->group_exit_code;
1707 stop_count = --sig->group_stop_count;
1710 current->exit_code = signr;
1711 set_current_state(TASK_STOPPED);
1713 spin_unlock_irq(&sighand->siglock);
1714 read_unlock(&tasklist_lock);
1717 finish_stop(stop_count);
1721 * Do appropriate magic when group_stop_count > 0.
1722 * We return nonzero if we stopped, after releasing the siglock.
1723 * We return zero if we still hold the siglock and should look
1724 * for another signal without checking group_stop_count again.
1726 static inline int handle_group_stop(void)
1730 if (current->signal->group_exit_task == current) {
1732 * Group stop is so we can do a core dump,
1733 * We are the initiating thread, so get on with it.
1735 current->signal->group_exit_task = NULL;
1739 if (current->signal->group_exit)
1741 * Group stop is so another thread can do a core dump,
1742 * or else we are racing against a death signal.
1743 * Just punt the stop so we can get the next signal.
1748 * There is a group stop in progress. We stop
1749 * without any associated signal being in our queue.
1751 stop_count = --current->signal->group_stop_count;
1752 current->exit_code = current->signal->group_exit_code;
1753 set_current_state(TASK_STOPPED);
1754 spin_unlock_irq(¤t->sighand->siglock);
1755 finish_stop(stop_count);
1759 int get_signal_to_deliver(siginfo_t *info, struct pt_regs *regs, void *cookie)
1761 sigset_t *mask = ¤t->blocked;
1765 spin_lock_irq(¤t->sighand->siglock);
1767 struct k_sigaction *ka;
1769 if (unlikely(current->signal->group_stop_count > 0) &&
1770 handle_group_stop())
1773 signr = dequeue_signal(current, mask, info);
1776 break; /* will return 0 */
1778 if ((signr == SIGSEGV) && print_fatal_signals) {
1779 spin_unlock_irq(¤t->sighand->siglock);
1780 print_fatal_signal(regs, signr);
1781 spin_lock_irq(¤t->sighand->siglock);
1783 if ((current->ptrace & PT_PTRACED) && signr != SIGKILL) {
1784 ptrace_signal_deliver(regs, cookie);
1787 * If there is a group stop in progress,
1788 * we must participate in the bookkeeping.
1790 if (current->signal->group_stop_count > 0)
1791 --current->signal->group_stop_count;
1793 /* Let the debugger run. */
1794 current->exit_code = signr;
1795 current->last_siginfo = info;
1796 set_current_state(TASK_STOPPED);
1797 spin_unlock_irq(¤t->sighand->siglock);
1798 notify_parent(current, SIGCHLD);
1801 current->last_siginfo = NULL;
1803 /* We're back. Did the debugger cancel the sig? */
1804 spin_lock_irq(¤t->sighand->siglock);
1805 signr = current->exit_code;
1809 current->exit_code = 0;
1811 /* Update the siginfo structure if the signal has
1812 changed. If the debugger wanted something
1813 specific in the siginfo structure then it should
1814 have updated *info via PTRACE_SETSIGINFO. */
1815 if (signr != info->si_signo) {
1816 info->si_signo = signr;
1818 info->si_code = SI_USER;
1819 info->si_pid = current->parent->pid;
1820 info->si_uid = current->parent->uid;
1823 /* If the (new) signal is now blocked, requeue it. */
1824 if (sigismember(¤t->blocked, signr)) {
1825 specific_send_sig_info(signr, info, current);
1830 ka = ¤t->sighand->action[signr-1];
1831 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
1833 if (ka->sa.sa_handler != SIG_DFL) /* Run the handler. */
1834 break; /* will return non-zero "signr" value */
1837 * Now we are doing the default action for this signal.
1839 if (sig_kernel_ignore(signr)) /* Default is nothing. */
1842 /* Init gets no signals it doesn't want. */
1843 if (current->pid == 1)
1846 if (sig_kernel_stop(signr)) {
1848 * The default action is to stop all threads in
1849 * the thread group. The job control signals
1850 * do nothing in an orphaned pgrp, but SIGSTOP
1851 * always works. Note that siglock needs to be
1852 * dropped during the call to is_orphaned_pgrp()
1853 * because of lock ordering with tasklist_lock.
1854 * This allows an intervening SIGCONT to be posted.
1855 * We need to check for that and bail out if necessary.
1857 if (signr == SIGSTOP) {
1858 do_signal_stop(signr); /* releases siglock */
1861 spin_unlock_irq(¤t->sighand->siglock);
1863 /* signals can be posted during this window */
1865 if (is_orphaned_pgrp(process_group(current)))
1868 spin_lock_irq(¤t->sighand->siglock);
1869 if (unlikely(sig_avoid_stop_race())) {
1871 * Either a SIGCONT or a SIGKILL signal was
1872 * posted in the siglock-not-held window.
1877 do_signal_stop(signr); /* releases siglock */
1881 spin_unlock_irq(¤t->sighand->siglock);
1884 * Anything else is fatal, maybe with a core dump.
1886 current->flags |= PF_SIGNALED;
1887 if (print_fatal_signals)
1888 print_fatal_signal(regs, signr);
1889 if (sig_kernel_coredump(signr) &&
1890 do_coredump((long)signr, signr, regs)) {
1892 * That killed all other threads in the group and
1893 * synchronized with their demise, so there can't
1894 * be any more left to kill now. The group_exit
1895 * flags are set by do_coredump. Note that
1896 * thread_group_empty won't always be true yet,
1897 * because those threads were blocked in __exit_mm
1898 * and we just let them go to finish dying.
1900 const int code = signr | 0x80;
1901 BUG_ON(!current->signal->group_exit);
1902 BUG_ON(current->signal->group_exit_code != code);
1908 * Death signals, no core dump.
1910 do_group_exit(signr);
1913 spin_unlock_irq(¤t->sighand->siglock);
1919 EXPORT_SYMBOL(recalc_sigpending);
1920 EXPORT_SYMBOL_GPL(dequeue_signal);
1921 EXPORT_SYMBOL(flush_signals);
1922 EXPORT_SYMBOL(force_sig);
1923 EXPORT_SYMBOL(force_sig_info);
1924 EXPORT_SYMBOL(kill_pg);
1925 EXPORT_SYMBOL(kill_pg_info);
1926 EXPORT_SYMBOL(kill_proc);
1927 EXPORT_SYMBOL(kill_proc_info);
1928 EXPORT_SYMBOL(kill_sl);
1929 EXPORT_SYMBOL(kill_sl_info);
1930 EXPORT_SYMBOL(notify_parent);
1931 EXPORT_SYMBOL(send_sig);
1932 EXPORT_SYMBOL(send_sig_info);
1933 EXPORT_SYMBOL(send_group_sig_info);
1934 EXPORT_SYMBOL(sigqueue_alloc);
1935 EXPORT_SYMBOL(sigqueue_free);
1936 EXPORT_SYMBOL(send_sigqueue);
1937 EXPORT_SYMBOL(send_group_sigqueue);
1938 EXPORT_SYMBOL(sigprocmask);
1939 EXPORT_SYMBOL(block_all_signals);
1940 EXPORT_SYMBOL(unblock_all_signals);
1944 * System call entry points.
1947 asmlinkage long sys_restart_syscall(void)
1949 struct restart_block *restart = ¤t_thread_info()->restart_block;
1950 return restart->fn(restart);
1953 long do_no_restart_syscall(struct restart_block *param)
1959 * We don't need to get the kernel lock - this is all local to this
1960 * particular thread.. (and that's good, because this is _heavily_
1961 * used by various programs)
1965 * This is also useful for kernel threads that want to temporarily
1966 * (or permanently) block certain signals.
1968 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
1969 * interface happily blocks "unblockable" signals like SIGKILL
1972 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
1977 spin_lock_irq(¤t->sighand->siglock);
1978 old_block = current->blocked;
1982 sigorsets(¤t->blocked, ¤t->blocked, set);
1985 signandsets(¤t->blocked, ¤t->blocked, set);
1988 current->blocked = *set;
1993 recalc_sigpending();
1994 spin_unlock_irq(¤t->sighand->siglock);
1996 *oldset = old_block;
2001 sys_rt_sigprocmask(int how, sigset_t __user *set, sigset_t __user *oset, size_t sigsetsize)
2003 int error = -EINVAL;
2004 sigset_t old_set, new_set;
2006 /* XXX: Don't preclude handling different sized sigset_t's. */
2007 if (sigsetsize != sizeof(sigset_t))
2012 if (copy_from_user(&new_set, set, sizeof(*set)))
2014 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2016 error = sigprocmask(how, &new_set, &old_set);
2022 spin_lock_irq(¤t->sighand->siglock);
2023 old_set = current->blocked;
2024 spin_unlock_irq(¤t->sighand->siglock);
2028 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2036 long do_sigpending(void __user *set, unsigned long sigsetsize)
2038 long error = -EINVAL;
2041 if (sigsetsize > sizeof(sigset_t))
2044 spin_lock_irq(¤t->sighand->siglock);
2045 sigorsets(&pending, ¤t->pending.signal,
2046 ¤t->signal->shared_pending.signal);
2047 spin_unlock_irq(¤t->sighand->siglock);
2049 /* Outside the lock because only this thread touches it. */
2050 sigandsets(&pending, ¤t->blocked, &pending);
2053 if (!copy_to_user(set, &pending, sigsetsize))
2061 sys_rt_sigpending(sigset_t __user *set, size_t sigsetsize)
2063 return do_sigpending(set, sigsetsize);
2066 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2068 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2072 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2074 if (from->si_code < 0)
2075 return __copy_to_user(to, from, sizeof(siginfo_t))
2078 * If you change siginfo_t structure, please be sure
2079 * this code is fixed accordingly.
2080 * It should never copy any pad contained in the structure
2081 * to avoid security leaks, but must copy the generic
2082 * 3 ints plus the relevant union member.
2084 err = __put_user(from->si_signo, &to->si_signo);
2085 err |= __put_user(from->si_errno, &to->si_errno);
2086 err |= __put_user((short)from->si_code, &to->si_code);
2087 switch (from->si_code & __SI_MASK) {
2089 err |= __put_user(from->si_pid, &to->si_pid);
2090 err |= __put_user(from->si_uid, &to->si_uid);
2093 err |= __put_user(from->si_tid, &to->si_tid);
2094 err |= __put_user(from->si_overrun, &to->si_overrun);
2095 err |= __put_user(from->si_ptr, &to->si_ptr);
2098 err |= __put_user(from->si_band, &to->si_band);
2099 err |= __put_user(from->si_fd, &to->si_fd);
2102 err |= __put_user(from->si_addr, &to->si_addr);
2103 #ifdef __ARCH_SI_TRAPNO
2104 err |= __put_user(from->si_trapno, &to->si_trapno);
2108 err |= __put_user(from->si_pid, &to->si_pid);
2109 err |= __put_user(from->si_uid, &to->si_uid);
2110 err |= __put_user(from->si_status, &to->si_status);
2111 err |= __put_user(from->si_utime, &to->si_utime);
2112 err |= __put_user(from->si_stime, &to->si_stime);
2114 case __SI_RT: /* This is not generated by the kernel as of now. */
2115 case __SI_MESGQ: /* But this is */
2116 err |= __put_user(from->si_pid, &to->si_pid);
2117 err |= __put_user(from->si_uid, &to->si_uid);
2118 err |= __put_user(from->si_ptr, &to->si_ptr);
2120 default: /* this is just in case for now ... */
2121 err |= __put_user(from->si_pid, &to->si_pid);
2122 err |= __put_user(from->si_uid, &to->si_uid);
2131 sys_rt_sigtimedwait(const sigset_t __user *uthese,
2132 siginfo_t __user *uinfo,
2133 const struct timespec __user *uts,
2142 /* XXX: Don't preclude handling different sized sigset_t's. */
2143 if (sigsetsize != sizeof(sigset_t))
2146 if (copy_from_user(&these, uthese, sizeof(these)))
2150 * Invert the set of allowed signals to get those we
2153 sigdelsetmask(&these, sigmask(SIGKILL)|sigmask(SIGSTOP));
2157 if (copy_from_user(&ts, uts, sizeof(ts)))
2159 if (ts.tv_nsec >= 1000000000L || ts.tv_nsec < 0
2164 spin_lock_irq(¤t->sighand->siglock);
2165 sig = dequeue_signal(current, &these, &info);
2167 timeout = MAX_SCHEDULE_TIMEOUT;
2169 timeout = (timespec_to_jiffies(&ts)
2170 + (ts.tv_sec || ts.tv_nsec));
2173 /* None ready -- temporarily unblock those we're
2174 * interested while we are sleeping in so that we'll
2175 * be awakened when they arrive. */
2176 current->real_blocked = current->blocked;
2177 sigandsets(¤t->blocked, ¤t->blocked, &these);
2178 recalc_sigpending();
2179 spin_unlock_irq(¤t->sighand->siglock);
2181 current->state = TASK_INTERRUPTIBLE;
2182 timeout = schedule_timeout(timeout);
2184 spin_lock_irq(¤t->sighand->siglock);
2185 sig = dequeue_signal(current, &these, &info);
2186 current->blocked = current->real_blocked;
2187 siginitset(¤t->real_blocked, 0);
2188 recalc_sigpending();
2191 spin_unlock_irq(¤t->sighand->siglock);
2196 if (copy_siginfo_to_user(uinfo, &info))
2209 sys_kill(int pid, int sig)
2211 struct siginfo info;
2213 info.si_signo = sig;
2215 info.si_code = SI_USER;
2216 info.si_pid = current->tgid;
2217 info.si_uid = current->uid;
2219 return kill_something_info(sig, &info, pid);
2223 * sys_tgkill - send signal to one specific thread
2224 * @tgid: the thread group ID of the thread
2225 * @pid: the PID of the thread
2226 * @sig: signal to be sent
2228 * This syscall also checks the tgid and returns -ESRCH even if the PID
2229 * exists but it's not belonging to the target process anymore. This
2230 * method solves the problem of threads exiting and PIDs getting reused.
2232 asmlinkage long sys_tgkill(int tgid, int pid, int sig)
2234 struct siginfo info;
2236 struct task_struct *p;
2238 /* This is only valid for single tasks */
2239 if (pid <= 0 || tgid <= 0)
2242 info.si_signo = sig;
2244 info.si_code = SI_TKILL;
2245 info.si_pid = current->tgid;
2246 info.si_uid = current->uid;
2248 read_lock(&tasklist_lock);
2249 p = find_task_by_pid(pid);
2251 if (p && (p->tgid == tgid)) {
2252 error = check_kill_permission(sig, &info, p);
2254 * The null signal is a permissions and process existence
2255 * probe. No signal is actually delivered.
2257 if (!error && sig && p->sighand) {
2258 spin_lock_irq(&p->sighand->siglock);
2259 handle_stop_signal(sig, p);
2260 error = specific_send_sig_info(sig, &info, p);
2261 spin_unlock_irq(&p->sighand->siglock);
2264 read_unlock(&tasklist_lock);
2269 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2272 sys_tkill(int pid, int sig)
2274 struct siginfo info;
2276 struct task_struct *p;
2278 /* This is only valid for single tasks */
2282 info.si_signo = sig;
2284 info.si_code = SI_TKILL;
2285 info.si_pid = current->tgid;
2286 info.si_uid = current->uid;
2288 read_lock(&tasklist_lock);
2289 p = find_task_by_pid(pid);
2292 error = check_kill_permission(sig, &info, p);
2294 * The null signal is a permissions and process existence
2295 * probe. No signal is actually delivered.
2297 if (!error && sig && p->sighand) {
2298 spin_lock_irq(&p->sighand->siglock);
2299 handle_stop_signal(sig, p);
2300 error = specific_send_sig_info(sig, &info, p);
2301 spin_unlock_irq(&p->sighand->siglock);
2304 read_unlock(&tasklist_lock);
2309 sys_rt_sigqueueinfo(int pid, int sig, siginfo_t __user *uinfo)
2313 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2316 /* Not even root can pretend to send signals from the kernel.
2317 Nor can they impersonate a kill(), which adds source info. */
2318 if (info.si_code >= 0)
2320 info.si_signo = sig;
2322 /* POSIX.1b doesn't mention process groups. */
2323 return kill_proc_info(sig, &info, pid);
2327 do_sigaction(int sig, const struct k_sigaction *act, struct k_sigaction *oact)
2329 struct k_sigaction *k;
2331 if (sig < 1 || sig > _NSIG || (act && sig_kernel_only(sig)))
2334 k = ¤t->sighand->action[sig-1];
2336 spin_lock_irq(¤t->sighand->siglock);
2337 if (signal_pending(current)) {
2339 * If there might be a fatal signal pending on multiple
2340 * threads, make sure we take it before changing the action.
2342 spin_unlock_irq(¤t->sighand->siglock);
2343 return -ERESTARTNOINTR;
2352 * "Setting a signal action to SIG_IGN for a signal that is
2353 * pending shall cause the pending signal to be discarded,
2354 * whether or not it is blocked."
2356 * "Setting a signal action to SIG_DFL for a signal that is
2357 * pending and whose default action is to ignore the signal
2358 * (for example, SIGCHLD), shall cause the pending signal to
2359 * be discarded, whether or not it is blocked"
2361 if (act->sa.sa_handler == SIG_IGN ||
2362 (act->sa.sa_handler == SIG_DFL &&
2363 sig_kernel_ignore(sig))) {
2365 * This is a fairly rare case, so we only take the
2366 * tasklist_lock once we're sure we'll need it.
2367 * Now we must do this little unlock and relock
2368 * dance to maintain the lock hierarchy.
2370 struct task_struct *t = current;
2371 spin_unlock_irq(&t->sighand->siglock);
2372 read_lock(&tasklist_lock);
2373 spin_lock_irq(&t->sighand->siglock);
2375 sigdelsetmask(&k->sa.sa_mask,
2376 sigmask(SIGKILL) | sigmask(SIGSTOP));
2377 rm_from_queue(sigmask(sig), &t->signal->shared_pending);
2379 rm_from_queue(sigmask(sig), &t->pending);
2380 recalc_sigpending_tsk(t);
2382 } while (t != current);
2383 spin_unlock_irq(¤t->sighand->siglock);
2384 read_unlock(&tasklist_lock);
2389 sigdelsetmask(&k->sa.sa_mask,
2390 sigmask(SIGKILL) | sigmask(SIGSTOP));
2393 spin_unlock_irq(¤t->sighand->siglock);
2398 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
2404 oss.ss_sp = (void __user *) current->sas_ss_sp;
2405 oss.ss_size = current->sas_ss_size;
2406 oss.ss_flags = sas_ss_flags(sp);
2415 if (verify_area(VERIFY_READ, uss, sizeof(*uss))
2416 || __get_user(ss_sp, &uss->ss_sp)
2417 || __get_user(ss_flags, &uss->ss_flags)
2418 || __get_user(ss_size, &uss->ss_size))
2422 if (on_sig_stack(sp))
2428 * Note - this code used to test ss_flags incorrectly
2429 * old code may have been written using ss_flags==0
2430 * to mean ss_flags==SS_ONSTACK (as this was the only
2431 * way that worked) - this fix preserves that older
2434 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
2437 if (ss_flags == SS_DISABLE) {
2442 if (ss_size < MINSIGSTKSZ)
2446 current->sas_ss_sp = (unsigned long) ss_sp;
2447 current->sas_ss_size = ss_size;
2452 if (copy_to_user(uoss, &oss, sizeof(oss)))
2461 #ifdef __ARCH_WANT_SYS_SIGPENDING
2464 sys_sigpending(old_sigset_t __user *set)
2466 return do_sigpending(set, sizeof(*set));
2471 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
2472 /* Some platforms have their own version with special arguments others
2473 support only sys_rt_sigprocmask. */
2476 sys_sigprocmask(int how, old_sigset_t __user *set, old_sigset_t __user *oset)
2479 old_sigset_t old_set, new_set;
2483 if (copy_from_user(&new_set, set, sizeof(*set)))
2485 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
2487 spin_lock_irq(¤t->sighand->siglock);
2488 old_set = current->blocked.sig[0];
2496 sigaddsetmask(¤t->blocked, new_set);
2499 sigdelsetmask(¤t->blocked, new_set);
2502 current->blocked.sig[0] = new_set;
2506 recalc_sigpending();
2507 spin_unlock_irq(¤t->sighand->siglock);
2513 old_set = current->blocked.sig[0];
2516 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2523 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
2525 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
2527 sys_rt_sigaction(int sig,
2528 const struct sigaction __user *act,
2529 struct sigaction __user *oact,
2532 struct k_sigaction new_sa, old_sa;
2535 /* XXX: Don't preclude handling different sized sigset_t's. */
2536 if (sigsetsize != sizeof(sigset_t))
2540 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
2544 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
2547 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
2553 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
2555 #ifdef __ARCH_WANT_SYS_SGETMASK
2558 * For backwards compatibility. Functionality superseded by sigprocmask.
2564 return current->blocked.sig[0];
2568 sys_ssetmask(int newmask)
2572 spin_lock_irq(¤t->sighand->siglock);
2573 old = current->blocked.sig[0];
2575 siginitset(¤t->blocked, newmask & ~(sigmask(SIGKILL)|
2577 recalc_sigpending();
2578 spin_unlock_irq(¤t->sighand->siglock);
2582 #endif /* __ARCH_WANT_SGETMASK */
2584 #ifdef __ARCH_WANT_SYS_SIGNAL
2586 * For backwards compatibility. Functionality superseded by sigaction.
2588 asmlinkage unsigned long
2589 sys_signal(int sig, __sighandler_t handler)
2591 struct k_sigaction new_sa, old_sa;
2594 new_sa.sa.sa_handler = handler;
2595 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
2597 ret = do_sigaction(sig, &new_sa, &old_sa);
2599 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
2601 #endif /* __ARCH_WANT_SYS_SIGNAL */
2603 #ifdef __ARCH_WANT_SYS_PAUSE
2608 current->state = TASK_INTERRUPTIBLE;
2610 return -ERESTARTNOHAND;
2615 void __init signals_init(void)
2618 kmem_cache_create("sigqueue",
2619 sizeof(struct sigqueue),
2620 __alignof__(struct sigqueue),
2621 SLAB_PANIC, NULL, NULL);