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/slab.h>
14 #include <linux/module.h>
15 #include <linux/init.h>
16 #include <linux/sched.h>
18 #include <linux/tty.h>
19 #include <linux/binfmts.h>
20 #include <linux/security.h>
21 #include <linux/syscalls.h>
22 #include <linux/ptrace.h>
23 #include <linux/signal.h>
24 #include <linux/signalfd.h>
25 #include <linux/capability.h>
26 #include <linux/freezer.h>
27 #include <linux/pid_namespace.h>
28 #include <linux/nsproxy.h>
30 #include <asm/param.h>
31 #include <asm/uaccess.h>
32 #include <asm/unistd.h>
33 #include <asm/siginfo.h>
34 #include "audit.h" /* audit_signal_info() */
37 * SLAB caches for signal bits.
40 static struct kmem_cache *sigqueue_cachep;
42 static int __sig_ignored(struct task_struct *t, int sig)
46 /* Is it explicitly or implicitly ignored? */
48 handler = t->sighand->action[sig - 1].sa.sa_handler;
49 return handler == SIG_IGN ||
50 (handler == SIG_DFL && sig_kernel_ignore(sig));
53 static int sig_ignored(struct task_struct *t, int sig)
56 * Tracers always want to know about signals..
58 if (t->ptrace & PT_PTRACED)
62 * Blocked signals are never ignored, since the
63 * signal handler may change by the time it is
66 if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
69 return __sig_ignored(t, sig);
73 * Re-calculate pending state from the set of locally pending
74 * signals, globally pending signals, and blocked signals.
76 static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
81 switch (_NSIG_WORDS) {
83 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
84 ready |= signal->sig[i] &~ blocked->sig[i];
87 case 4: ready = signal->sig[3] &~ blocked->sig[3];
88 ready |= signal->sig[2] &~ blocked->sig[2];
89 ready |= signal->sig[1] &~ blocked->sig[1];
90 ready |= signal->sig[0] &~ blocked->sig[0];
93 case 2: ready = signal->sig[1] &~ blocked->sig[1];
94 ready |= signal->sig[0] &~ blocked->sig[0];
97 case 1: ready = signal->sig[0] &~ blocked->sig[0];
102 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
104 static int recalc_sigpending_tsk(struct task_struct *t)
106 if (t->signal->group_stop_count > 0 ||
107 PENDING(&t->pending, &t->blocked) ||
108 PENDING(&t->signal->shared_pending, &t->blocked)) {
109 set_tsk_thread_flag(t, TIF_SIGPENDING);
113 * We must never clear the flag in another thread, or in current
114 * when it's possible the current syscall is returning -ERESTART*.
115 * So we don't clear it here, and only callers who know they should do.
121 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
122 * This is superfluous when called on current, the wakeup is a harmless no-op.
124 void recalc_sigpending_and_wake(struct task_struct *t)
126 if (recalc_sigpending_tsk(t))
127 signal_wake_up(t, 0);
130 void recalc_sigpending(void)
132 if (!recalc_sigpending_tsk(current) && !freezing(current))
133 clear_thread_flag(TIF_SIGPENDING);
137 /* Given the mask, find the first available signal that should be serviced. */
139 int next_signal(struct sigpending *pending, sigset_t *mask)
141 unsigned long i, *s, *m, x;
144 s = pending->signal.sig;
146 switch (_NSIG_WORDS) {
148 for (i = 0; i < _NSIG_WORDS; ++i, ++s, ++m)
149 if ((x = *s &~ *m) != 0) {
150 sig = ffz(~x) + i*_NSIG_BPW + 1;
155 case 2: if ((x = s[0] &~ m[0]) != 0)
157 else if ((x = s[1] &~ m[1]) != 0)
164 case 1: if ((x = *s &~ *m) != 0)
172 static struct sigqueue *__sigqueue_alloc(struct task_struct *t, gfp_t flags,
175 struct sigqueue *q = NULL;
176 struct user_struct *user;
179 * In order to avoid problems with "switch_user()", we want to make
180 * sure that the compiler doesn't re-load "t->user"
184 atomic_inc(&user->sigpending);
185 if (override_rlimit ||
186 atomic_read(&user->sigpending) <=
187 t->signal->rlim[RLIMIT_SIGPENDING].rlim_cur)
188 q = kmem_cache_alloc(sigqueue_cachep, flags);
189 if (unlikely(q == NULL)) {
190 atomic_dec(&user->sigpending);
192 INIT_LIST_HEAD(&q->list);
194 q->user = get_uid(user);
199 static void __sigqueue_free(struct sigqueue *q)
201 if (q->flags & SIGQUEUE_PREALLOC)
203 atomic_dec(&q->user->sigpending);
205 kmem_cache_free(sigqueue_cachep, q);
208 void flush_sigqueue(struct sigpending *queue)
212 sigemptyset(&queue->signal);
213 while (!list_empty(&queue->list)) {
214 q = list_entry(queue->list.next, struct sigqueue , list);
215 list_del_init(&q->list);
221 * Flush all pending signals for a task.
223 void flush_signals(struct task_struct *t)
227 spin_lock_irqsave(&t->sighand->siglock, flags);
228 clear_tsk_thread_flag(t, TIF_SIGPENDING);
229 flush_sigqueue(&t->pending);
230 flush_sigqueue(&t->signal->shared_pending);
231 spin_unlock_irqrestore(&t->sighand->siglock, flags);
234 void ignore_signals(struct task_struct *t)
238 for (i = 0; i < _NSIG; ++i)
239 t->sighand->action[i].sa.sa_handler = SIG_IGN;
245 * Flush all handlers for a task.
249 flush_signal_handlers(struct task_struct *t, int force_default)
252 struct k_sigaction *ka = &t->sighand->action[0];
253 for (i = _NSIG ; i != 0 ; i--) {
254 if (force_default || ka->sa.sa_handler != SIG_IGN)
255 ka->sa.sa_handler = SIG_DFL;
257 sigemptyset(&ka->sa.sa_mask);
262 int unhandled_signal(struct task_struct *tsk, int sig)
264 if (is_global_init(tsk))
266 if (tsk->ptrace & PT_PTRACED)
268 return (tsk->sighand->action[sig-1].sa.sa_handler == SIG_IGN) ||
269 (tsk->sighand->action[sig-1].sa.sa_handler == SIG_DFL);
273 /* Notify the system that a driver wants to block all signals for this
274 * process, and wants to be notified if any signals at all were to be
275 * sent/acted upon. If the notifier routine returns non-zero, then the
276 * signal will be acted upon after all. If the notifier routine returns 0,
277 * then then signal will be blocked. Only one block per process is
278 * allowed. priv is a pointer to private data that the notifier routine
279 * can use to determine if the signal should be blocked or not. */
282 block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
286 spin_lock_irqsave(¤t->sighand->siglock, flags);
287 current->notifier_mask = mask;
288 current->notifier_data = priv;
289 current->notifier = notifier;
290 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
293 /* Notify the system that blocking has ended. */
296 unblock_all_signals(void)
300 spin_lock_irqsave(¤t->sighand->siglock, flags);
301 current->notifier = NULL;
302 current->notifier_data = NULL;
304 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
307 static int collect_signal(int sig, struct sigpending *list, siginfo_t *info)
309 struct sigqueue *q, *first = NULL;
310 int still_pending = 0;
312 if (unlikely(!sigismember(&list->signal, sig)))
316 * Collect the siginfo appropriate to this signal. Check if
317 * there is another siginfo for the same signal.
319 list_for_each_entry(q, &list->list, list) {
320 if (q->info.si_signo == sig) {
329 list_del_init(&first->list);
330 copy_siginfo(info, &first->info);
331 __sigqueue_free(first);
333 sigdelset(&list->signal, sig);
336 /* Ok, it wasn't in the queue. This must be
337 a fast-pathed signal or we must have been
338 out of queue space. So zero out the info.
340 sigdelset(&list->signal, sig);
341 info->si_signo = sig;
350 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
353 int sig = next_signal(pending, mask);
356 if (current->notifier) {
357 if (sigismember(current->notifier_mask, sig)) {
358 if (!(current->notifier)(current->notifier_data)) {
359 clear_thread_flag(TIF_SIGPENDING);
365 if (!collect_signal(sig, pending, info))
373 * Dequeue a signal and return the element to the caller, which is
374 * expected to free it.
376 * All callers have to hold the siglock.
378 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
382 /* We only dequeue private signals from ourselves, we don't let
383 * signalfd steal them
385 signr = __dequeue_signal(&tsk->pending, mask, info);
387 signr = __dequeue_signal(&tsk->signal->shared_pending,
392 * itimers are process shared and we restart periodic
393 * itimers in the signal delivery path to prevent DoS
394 * attacks in the high resolution timer case. This is
395 * compliant with the old way of self restarting
396 * itimers, as the SIGALRM is a legacy signal and only
397 * queued once. Changing the restart behaviour to
398 * restart the timer in the signal dequeue path is
399 * reducing the timer noise on heavy loaded !highres
402 if (unlikely(signr == SIGALRM)) {
403 struct hrtimer *tmr = &tsk->signal->real_timer;
405 if (!hrtimer_is_queued(tmr) &&
406 tsk->signal->it_real_incr.tv64 != 0) {
407 hrtimer_forward(tmr, tmr->base->get_time(),
408 tsk->signal->it_real_incr);
409 hrtimer_restart(tmr);
418 if (unlikely(sig_kernel_stop(signr))) {
420 * Set a marker that we have dequeued a stop signal. Our
421 * caller might release the siglock and then the pending
422 * stop signal it is about to process is no longer in the
423 * pending bitmasks, but must still be cleared by a SIGCONT
424 * (and overruled by a SIGKILL). So those cases clear this
425 * shared flag after we've set it. Note that this flag may
426 * remain set after the signal we return is ignored or
427 * handled. That doesn't matter because its only purpose
428 * is to alert stop-signal processing code when another
429 * processor has come along and cleared the flag.
431 if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT))
432 tsk->signal->flags |= SIGNAL_STOP_DEQUEUED;
434 if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
436 * Release the siglock to ensure proper locking order
437 * of timer locks outside of siglocks. Note, we leave
438 * irqs disabled here, since the posix-timers code is
439 * about to disable them again anyway.
441 spin_unlock(&tsk->sighand->siglock);
442 do_schedule_next_timer(info);
443 spin_lock(&tsk->sighand->siglock);
449 * Tell a process that it has a new active signal..
451 * NOTE! we rely on the previous spin_lock to
452 * lock interrupts for us! We can only be called with
453 * "siglock" held, and the local interrupt must
454 * have been disabled when that got acquired!
456 * No need to set need_resched since signal event passing
457 * goes through ->blocked
459 void signal_wake_up(struct task_struct *t, int resume)
463 set_tsk_thread_flag(t, TIF_SIGPENDING);
466 * For SIGKILL, we want to wake it up in the stopped/traced/killable
467 * case. We don't check t->state here because there is a race with it
468 * executing another processor and just now entering stopped state.
469 * By using wake_up_state, we ensure the process will wake up and
470 * handle its death signal.
472 mask = TASK_INTERRUPTIBLE;
474 mask |= TASK_WAKEKILL;
475 if (!wake_up_state(t, mask))
480 * Remove signals in mask from the pending set and queue.
481 * Returns 1 if any signals were found.
483 * All callers must be holding the siglock.
485 * This version takes a sigset mask and looks at all signals,
486 * not just those in the first mask word.
488 static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
490 struct sigqueue *q, *n;
493 sigandsets(&m, mask, &s->signal);
494 if (sigisemptyset(&m))
497 signandsets(&s->signal, &s->signal, mask);
498 list_for_each_entry_safe(q, n, &s->list, list) {
499 if (sigismember(mask, q->info.si_signo)) {
500 list_del_init(&q->list);
507 * Remove signals in mask from the pending set and queue.
508 * Returns 1 if any signals were found.
510 * All callers must be holding the siglock.
512 static int rm_from_queue(unsigned long mask, struct sigpending *s)
514 struct sigqueue *q, *n;
516 if (!sigtestsetmask(&s->signal, mask))
519 sigdelsetmask(&s->signal, mask);
520 list_for_each_entry_safe(q, n, &s->list, list) {
521 if (q->info.si_signo < SIGRTMIN &&
522 (mask & sigmask(q->info.si_signo))) {
523 list_del_init(&q->list);
531 * Bad permissions for sending the signal
533 static int check_kill_permission(int sig, struct siginfo *info,
534 struct task_struct *t)
538 if (!valid_signal(sig))
541 if (info != SEND_SIG_NOINFO && (is_si_special(info) || SI_FROMKERNEL(info)))
544 error = audit_signal_info(sig, t); /* Let audit system see the signal */
548 if (((sig != SIGCONT) || (task_session_nr(current) != task_session_nr(t)))
549 && (current->euid ^ t->suid) && (current->euid ^ t->uid)
550 && (current->uid ^ t->suid) && (current->uid ^ t->uid)
551 && !capable(CAP_KILL))
554 return security_task_kill(t, info, sig, 0);
558 static void do_notify_parent_cldstop(struct task_struct *tsk, int why);
561 * Handle magic process-wide effects of stop/continue signals.
562 * Unlike the signal actions, these happen immediately at signal-generation
563 * time regardless of blocking, ignoring, or handling. This does the
564 * actual continuing for SIGCONT, but not the actual stopping for stop
565 * signals. The process stop is done as a signal action for SIG_DFL.
567 static void handle_stop_signal(int sig, struct task_struct *p)
569 struct signal_struct *signal = p->signal;
570 struct task_struct *t;
572 if (signal->flags & SIGNAL_GROUP_EXIT)
574 * The process is in the middle of dying already.
578 if (sig_kernel_stop(sig)) {
580 * This is a stop signal. Remove SIGCONT from all queues.
582 rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
585 rm_from_queue(sigmask(SIGCONT), &t->pending);
586 } while_each_thread(p, t);
587 } else if (sig == SIGCONT) {
590 * Remove all stop signals from all queues,
591 * and wake all threads.
593 rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
597 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
599 * If there is a handler for SIGCONT, we must make
600 * sure that no thread returns to user mode before
601 * we post the signal, in case it was the only
602 * thread eligible to run the signal handler--then
603 * it must not do anything between resuming and
604 * running the handler. With the TIF_SIGPENDING
605 * flag set, the thread will pause and acquire the
606 * siglock that we hold now and until we've queued
607 * the pending signal.
609 * Wake up the stopped thread _after_ setting
612 state = __TASK_STOPPED;
613 if (sig_user_defined(t, SIGCONT) && !sigismember(&t->blocked, SIGCONT)) {
614 set_tsk_thread_flag(t, TIF_SIGPENDING);
615 state |= TASK_INTERRUPTIBLE;
617 wake_up_state(t, state);
618 } while_each_thread(p, t);
621 * Notify the parent with CLD_CONTINUED if we were stopped.
623 * If we were in the middle of a group stop, we pretend it
624 * was already finished, and then continued. Since SIGCHLD
625 * doesn't queue we report only CLD_STOPPED, as if the next
626 * CLD_CONTINUED was dropped.
629 if (signal->flags & SIGNAL_STOP_STOPPED)
630 why |= SIGNAL_CLD_CONTINUED;
631 else if (signal->group_stop_count)
632 why |= SIGNAL_CLD_STOPPED;
635 signal->flags = why | SIGNAL_STOP_CONTINUED;
636 signal->group_stop_count = 0;
637 signal->group_exit_code = 0;
640 * We are not stopped, but there could be a stop
641 * signal in the middle of being processed after
642 * being removed from the queue. Clear that too.
644 signal->flags &= ~SIGNAL_STOP_DEQUEUED;
646 } else if (sig == SIGKILL) {
648 * Make sure that any pending stop signal already dequeued
649 * is undone by the wakeup for SIGKILL.
651 signal->flags &= ~SIGNAL_STOP_DEQUEUED;
656 * Test if P wants to take SIG. After we've checked all threads with this,
657 * it's equivalent to finding no threads not blocking SIG. Any threads not
658 * blocking SIG were ruled out because they are not running and already
659 * have pending signals. Such threads will dequeue from the shared queue
660 * as soon as they're available, so putting the signal on the shared queue
661 * will be equivalent to sending it to one such thread.
663 static inline int wants_signal(int sig, struct task_struct *p)
665 if (sigismember(&p->blocked, sig))
667 if (p->flags & PF_EXITING)
671 if (task_is_stopped_or_traced(p))
673 return task_curr(p) || !signal_pending(p);
676 static void complete_signal(int sig, struct task_struct *p, int group)
678 struct signal_struct *signal = p->signal;
679 struct task_struct *t;
682 * Now find a thread we can wake up to take the signal off the queue.
684 * If the main thread wants the signal, it gets first crack.
685 * Probably the least surprising to the average bear.
687 if (wants_signal(sig, p))
689 else if (!group || thread_group_empty(p))
691 * There is just one thread and it does not need to be woken.
692 * It will dequeue unblocked signals before it runs again.
697 * Otherwise try to find a suitable thread.
699 t = signal->curr_target;
700 while (!wants_signal(sig, t)) {
702 if (t == signal->curr_target)
704 * No thread needs to be woken.
705 * Any eligible threads will see
706 * the signal in the queue soon.
710 signal->curr_target = t;
714 * Found a killable thread. If the signal will be fatal,
715 * then start taking the whole group down immediately.
717 if (sig_fatal(p, sig) && !(signal->flags & SIGNAL_GROUP_EXIT) &&
718 !sigismember(&t->real_blocked, sig) &&
719 (sig == SIGKILL || !(t->ptrace & PT_PTRACED))) {
721 * This signal will be fatal to the whole group.
723 if (!sig_kernel_coredump(sig)) {
725 * Start a group exit and wake everybody up.
726 * This way we don't have other threads
727 * running and doing things after a slower
728 * thread has the fatal signal pending.
730 signal->flags = SIGNAL_GROUP_EXIT;
731 signal->group_exit_code = sig;
732 signal->group_stop_count = 0;
735 sigaddset(&t->pending.signal, SIGKILL);
736 signal_wake_up(t, 1);
737 } while_each_thread(p, t);
743 * The signal is already in the shared-pending queue.
744 * Tell the chosen thread to wake up and dequeue it.
746 signal_wake_up(t, sig == SIGKILL);
750 static inline int legacy_queue(struct sigpending *signals, int sig)
752 return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
755 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
758 struct sigpending *pending;
761 assert_spin_locked(&t->sighand->siglock);
762 handle_stop_signal(sig, t);
764 pending = group ? &t->signal->shared_pending : &t->pending;
766 * Short-circuit ignored signals and support queuing
767 * exactly one non-rt signal, so that we can get more
768 * detailed information about the cause of the signal.
770 if (sig_ignored(t, sig) || legacy_queue(pending, sig))
774 * Deliver the signal to listening signalfds. This must be called
775 * with the sighand lock held.
777 signalfd_notify(t, sig);
780 * fast-pathed signals for kernel-internal things like SIGSTOP
783 if (info == SEND_SIG_FORCED)
786 /* Real-time signals must be queued if sent by sigqueue, or
787 some other real-time mechanism. It is implementation
788 defined whether kill() does so. We attempt to do so, on
789 the principle of least surprise, but since kill is not
790 allowed to fail with EAGAIN when low on memory we just
791 make sure at least one signal gets delivered and don't
792 pass on the info struct. */
794 q = __sigqueue_alloc(t, GFP_ATOMIC, (sig < SIGRTMIN &&
795 (is_si_special(info) ||
796 info->si_code >= 0)));
798 list_add_tail(&q->list, &pending->list);
799 switch ((unsigned long) info) {
800 case (unsigned long) SEND_SIG_NOINFO:
801 q->info.si_signo = sig;
802 q->info.si_errno = 0;
803 q->info.si_code = SI_USER;
804 q->info.si_pid = task_pid_vnr(current);
805 q->info.si_uid = current->uid;
807 case (unsigned long) SEND_SIG_PRIV:
808 q->info.si_signo = sig;
809 q->info.si_errno = 0;
810 q->info.si_code = SI_KERNEL;
815 copy_siginfo(&q->info, info);
818 } else if (!is_si_special(info)) {
819 if (sig >= SIGRTMIN && info->si_code != SI_USER)
821 * Queue overflow, abort. We may abort if the signal was rt
822 * and sent by user using something other than kill().
828 sigaddset(&pending->signal, sig);
829 complete_signal(sig, t, group);
833 int print_fatal_signals;
835 static void print_fatal_signal(struct pt_regs *regs, int signr)
837 printk("%s/%d: potentially unexpected fatal signal %d.\n",
838 current->comm, task_pid_nr(current), signr);
840 #if defined(__i386__) && !defined(__arch_um__)
841 printk("code at %08lx: ", regs->ip);
844 for (i = 0; i < 16; i++) {
847 __get_user(insn, (unsigned char *)(regs->ip + i));
848 printk("%02x ", insn);
856 static int __init setup_print_fatal_signals(char *str)
858 get_option (&str, &print_fatal_signals);
863 __setup("print-fatal-signals=", setup_print_fatal_signals);
866 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
868 return send_signal(sig, info, p, 1);
872 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
874 return send_signal(sig, info, t, 0);
878 * Force a signal that the process can't ignore: if necessary
879 * we unblock the signal and change any SIG_IGN to SIG_DFL.
881 * Note: If we unblock the signal, we always reset it to SIG_DFL,
882 * since we do not want to have a signal handler that was blocked
883 * be invoked when user space had explicitly blocked it.
885 * We don't want to have recursive SIGSEGV's etc, for example.
888 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
890 unsigned long int flags;
891 int ret, blocked, ignored;
892 struct k_sigaction *action;
894 spin_lock_irqsave(&t->sighand->siglock, flags);
895 action = &t->sighand->action[sig-1];
896 ignored = action->sa.sa_handler == SIG_IGN;
897 blocked = sigismember(&t->blocked, sig);
898 if (blocked || ignored) {
899 action->sa.sa_handler = SIG_DFL;
901 sigdelset(&t->blocked, sig);
902 recalc_sigpending_and_wake(t);
905 ret = specific_send_sig_info(sig, info, t);
906 spin_unlock_irqrestore(&t->sighand->siglock, flags);
912 force_sig_specific(int sig, struct task_struct *t)
914 force_sig_info(sig, SEND_SIG_FORCED, t);
918 * Nuke all other threads in the group.
920 void zap_other_threads(struct task_struct *p)
922 struct task_struct *t;
924 p->signal->group_stop_count = 0;
926 for (t = next_thread(p); t != p; t = next_thread(t)) {
928 * Don't bother with already dead threads
933 /* SIGKILL will be handled before any pending SIGSTOP */
934 sigaddset(&t->pending.signal, SIGKILL);
935 signal_wake_up(t, 1);
939 int __fatal_signal_pending(struct task_struct *tsk)
941 return sigismember(&tsk->pending.signal, SIGKILL);
943 EXPORT_SYMBOL(__fatal_signal_pending);
945 struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long *flags)
947 struct sighand_struct *sighand;
951 sighand = rcu_dereference(tsk->sighand);
952 if (unlikely(sighand == NULL))
955 spin_lock_irqsave(&sighand->siglock, *flags);
956 if (likely(sighand == tsk->sighand))
958 spin_unlock_irqrestore(&sighand->siglock, *flags);
965 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
970 ret = check_kill_permission(sig, info, p);
974 if (lock_task_sighand(p, &flags)) {
975 ret = __group_send_sig_info(sig, info, p);
976 unlock_task_sighand(p, &flags);
984 * __kill_pgrp_info() sends a signal to a process group: this is what the tty
985 * control characters do (^C, ^Z etc)
988 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
990 struct task_struct *p = NULL;
995 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
996 int err = group_send_sig_info(sig, info, p);
999 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
1000 return success ? 0 : retval;
1003 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
1006 struct task_struct *p;
1010 p = pid_task(pid, PIDTYPE_PID);
1012 error = group_send_sig_info(sig, info, p);
1013 if (unlikely(error == -ESRCH))
1015 * The task was unhashed in between, try again.
1016 * If it is dead, pid_task() will return NULL,
1017 * if we race with de_thread() it will find the
1028 kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1032 error = kill_pid_info(sig, info, find_vpid(pid));
1037 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
1038 int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
1039 uid_t uid, uid_t euid, u32 secid)
1042 struct task_struct *p;
1044 if (!valid_signal(sig))
1047 read_lock(&tasklist_lock);
1048 p = pid_task(pid, PIDTYPE_PID);
1053 if ((info == SEND_SIG_NOINFO || (!is_si_special(info) && SI_FROMUSER(info)))
1054 && (euid != p->suid) && (euid != p->uid)
1055 && (uid != p->suid) && (uid != p->uid)) {
1059 ret = security_task_kill(p, info, sig, secid);
1062 if (sig && p->sighand) {
1063 unsigned long flags;
1064 spin_lock_irqsave(&p->sighand->siglock, flags);
1065 ret = __group_send_sig_info(sig, info, p);
1066 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1069 read_unlock(&tasklist_lock);
1072 EXPORT_SYMBOL_GPL(kill_pid_info_as_uid);
1075 * kill_something_info() interprets pid in interesting ways just like kill(2).
1077 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1078 * is probably wrong. Should make it like BSD or SYSV.
1081 static int kill_something_info(int sig, struct siginfo *info, int pid)
1087 ret = kill_pid_info(sig, info, find_vpid(pid));
1092 read_lock(&tasklist_lock);
1094 ret = __kill_pgrp_info(sig, info,
1095 pid ? find_vpid(-pid) : task_pgrp(current));
1097 int retval = 0, count = 0;
1098 struct task_struct * p;
1100 for_each_process(p) {
1101 if (p->pid > 1 && !same_thread_group(p, current)) {
1102 int err = group_send_sig_info(sig, info, p);
1108 ret = count ? retval : -ESRCH;
1110 read_unlock(&tasklist_lock);
1116 * These are for backward compatibility with the rest of the kernel source.
1120 * The caller must ensure the task can't exit.
1123 send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1126 unsigned long flags;
1129 * Make sure legacy kernel users don't send in bad values
1130 * (normal paths check this in check_kill_permission).
1132 if (!valid_signal(sig))
1135 spin_lock_irqsave(&p->sighand->siglock, flags);
1136 ret = specific_send_sig_info(sig, info, p);
1137 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1141 #define __si_special(priv) \
1142 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1145 send_sig(int sig, struct task_struct *p, int priv)
1147 return send_sig_info(sig, __si_special(priv), p);
1151 force_sig(int sig, struct task_struct *p)
1153 force_sig_info(sig, SEND_SIG_PRIV, p);
1157 * When things go south during signal handling, we
1158 * will force a SIGSEGV. And if the signal that caused
1159 * the problem was already a SIGSEGV, we'll want to
1160 * make sure we don't even try to deliver the signal..
1163 force_sigsegv(int sig, struct task_struct *p)
1165 if (sig == SIGSEGV) {
1166 unsigned long flags;
1167 spin_lock_irqsave(&p->sighand->siglock, flags);
1168 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1169 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1171 force_sig(SIGSEGV, p);
1175 int kill_pgrp(struct pid *pid, int sig, int priv)
1179 read_lock(&tasklist_lock);
1180 ret = __kill_pgrp_info(sig, __si_special(priv), pid);
1181 read_unlock(&tasklist_lock);
1185 EXPORT_SYMBOL(kill_pgrp);
1187 int kill_pid(struct pid *pid, int sig, int priv)
1189 return kill_pid_info(sig, __si_special(priv), pid);
1191 EXPORT_SYMBOL(kill_pid);
1194 kill_proc(pid_t pid, int sig, int priv)
1199 ret = kill_pid_info(sig, __si_special(priv), find_pid(pid));
1205 * These functions support sending signals using preallocated sigqueue
1206 * structures. This is needed "because realtime applications cannot
1207 * afford to lose notifications of asynchronous events, like timer
1208 * expirations or I/O completions". In the case of Posix Timers
1209 * we allocate the sigqueue structure from the timer_create. If this
1210 * allocation fails we are able to report the failure to the application
1211 * with an EAGAIN error.
1214 struct sigqueue *sigqueue_alloc(void)
1218 if ((q = __sigqueue_alloc(current, GFP_KERNEL, 0)))
1219 q->flags |= SIGQUEUE_PREALLOC;
1223 void sigqueue_free(struct sigqueue *q)
1225 unsigned long flags;
1226 spinlock_t *lock = ¤t->sighand->siglock;
1228 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1230 * If the signal is still pending remove it from the
1231 * pending queue. We must hold ->siglock while testing
1232 * q->list to serialize with collect_signal().
1234 spin_lock_irqsave(lock, flags);
1235 if (!list_empty(&q->list))
1236 list_del_init(&q->list);
1237 spin_unlock_irqrestore(lock, flags);
1239 q->flags &= ~SIGQUEUE_PREALLOC;
1243 static int do_send_sigqueue(struct sigqueue *q, struct task_struct *t,
1246 int sig = q->info.si_signo;
1247 struct sigpending *pending;
1248 unsigned long flags;
1251 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1254 if (!likely(lock_task_sighand(t, &flags)))
1257 handle_stop_signal(sig, t);
1260 if (sig_ignored(t, sig))
1264 if (unlikely(!list_empty(&q->list))) {
1266 * If an SI_TIMER entry is already queue just increment
1267 * the overrun count.
1270 BUG_ON(q->info.si_code != SI_TIMER);
1271 q->info.si_overrun++;
1275 signalfd_notify(t, sig);
1276 pending = group ? &t->signal->shared_pending : &t->pending;
1277 list_add_tail(&q->list, &pending->list);
1278 sigaddset(&pending->signal, sig);
1279 complete_signal(sig, t, group);
1281 unlock_task_sighand(t, &flags);
1286 int send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
1288 return do_send_sigqueue(q, p, 0);
1292 send_group_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
1294 return do_send_sigqueue(q, p, 1);
1298 * Wake up any threads in the parent blocked in wait* syscalls.
1300 static inline void __wake_up_parent(struct task_struct *p,
1301 struct task_struct *parent)
1303 wake_up_interruptible_sync(&parent->signal->wait_chldexit);
1307 * Let a parent know about the death of a child.
1308 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1311 void do_notify_parent(struct task_struct *tsk, int sig)
1313 struct siginfo info;
1314 unsigned long flags;
1315 struct sighand_struct *psig;
1319 /* do_notify_parent_cldstop should have been called instead. */
1320 BUG_ON(task_is_stopped_or_traced(tsk));
1322 BUG_ON(!tsk->ptrace &&
1323 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1325 info.si_signo = sig;
1328 * we are under tasklist_lock here so our parent is tied to
1329 * us and cannot exit and release its namespace.
1331 * the only it can is to switch its nsproxy with sys_unshare,
1332 * bu uncharing pid namespaces is not allowed, so we'll always
1333 * see relevant namespace
1335 * write_lock() currently calls preempt_disable() which is the
1336 * same as rcu_read_lock(), but according to Oleg, this is not
1337 * correct to rely on this
1340 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1343 info.si_uid = tsk->uid;
1345 /* FIXME: find out whether or not this is supposed to be c*time. */
1346 info.si_utime = cputime_to_jiffies(cputime_add(tsk->utime,
1347 tsk->signal->utime));
1348 info.si_stime = cputime_to_jiffies(cputime_add(tsk->stime,
1349 tsk->signal->stime));
1351 info.si_status = tsk->exit_code & 0x7f;
1352 if (tsk->exit_code & 0x80)
1353 info.si_code = CLD_DUMPED;
1354 else if (tsk->exit_code & 0x7f)
1355 info.si_code = CLD_KILLED;
1357 info.si_code = CLD_EXITED;
1358 info.si_status = tsk->exit_code >> 8;
1361 psig = tsk->parent->sighand;
1362 spin_lock_irqsave(&psig->siglock, flags);
1363 if (!tsk->ptrace && sig == SIGCHLD &&
1364 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1365 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1367 * We are exiting and our parent doesn't care. POSIX.1
1368 * defines special semantics for setting SIGCHLD to SIG_IGN
1369 * or setting the SA_NOCLDWAIT flag: we should be reaped
1370 * automatically and not left for our parent's wait4 call.
1371 * Rather than having the parent do it as a magic kind of
1372 * signal handler, we just set this to tell do_exit that we
1373 * can be cleaned up without becoming a zombie. Note that
1374 * we still call __wake_up_parent in this case, because a
1375 * blocked sys_wait4 might now return -ECHILD.
1377 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1378 * is implementation-defined: we do (if you don't want
1379 * it, just use SIG_IGN instead).
1381 tsk->exit_signal = -1;
1382 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1385 if (valid_signal(sig) && sig > 0)
1386 __group_send_sig_info(sig, &info, tsk->parent);
1387 __wake_up_parent(tsk, tsk->parent);
1388 spin_unlock_irqrestore(&psig->siglock, flags);
1391 static void do_notify_parent_cldstop(struct task_struct *tsk, int why)
1393 struct siginfo info;
1394 unsigned long flags;
1395 struct task_struct *parent;
1396 struct sighand_struct *sighand;
1398 if (tsk->ptrace & PT_PTRACED)
1399 parent = tsk->parent;
1401 tsk = tsk->group_leader;
1402 parent = tsk->real_parent;
1405 info.si_signo = SIGCHLD;
1408 * see comment in do_notify_parent() abot the following 3 lines
1411 info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
1414 info.si_uid = tsk->uid;
1416 /* FIXME: find out whether or not this is supposed to be c*time. */
1417 info.si_utime = cputime_to_jiffies(tsk->utime);
1418 info.si_stime = cputime_to_jiffies(tsk->stime);
1423 info.si_status = SIGCONT;
1426 info.si_status = tsk->signal->group_exit_code & 0x7f;
1429 info.si_status = tsk->exit_code & 0x7f;
1435 sighand = parent->sighand;
1436 spin_lock_irqsave(&sighand->siglock, flags);
1437 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1438 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1439 __group_send_sig_info(SIGCHLD, &info, parent);
1441 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1443 __wake_up_parent(tsk, parent);
1444 spin_unlock_irqrestore(&sighand->siglock, flags);
1447 static inline int may_ptrace_stop(void)
1449 if (!likely(current->ptrace & PT_PTRACED))
1452 * Are we in the middle of do_coredump?
1453 * If so and our tracer is also part of the coredump stopping
1454 * is a deadlock situation, and pointless because our tracer
1455 * is dead so don't allow us to stop.
1456 * If SIGKILL was already sent before the caller unlocked
1457 * ->siglock we must see ->core_waiters != 0. Otherwise it
1458 * is safe to enter schedule().
1460 if (unlikely(current->mm->core_waiters) &&
1461 unlikely(current->mm == current->parent->mm))
1468 * Return nonzero if there is a SIGKILL that should be waking us up.
1469 * Called with the siglock held.
1471 static int sigkill_pending(struct task_struct *tsk)
1473 return ((sigismember(&tsk->pending.signal, SIGKILL) ||
1474 sigismember(&tsk->signal->shared_pending.signal, SIGKILL)) &&
1475 !unlikely(sigismember(&tsk->blocked, SIGKILL)));
1479 * This must be called with current->sighand->siglock held.
1481 * This should be the path for all ptrace stops.
1482 * We always set current->last_siginfo while stopped here.
1483 * That makes it a way to test a stopped process for
1484 * being ptrace-stopped vs being job-control-stopped.
1486 * If we actually decide not to stop at all because the tracer
1487 * is gone, we keep current->exit_code unless clear_code.
1489 static void ptrace_stop(int exit_code, int clear_code, siginfo_t *info)
1493 if (arch_ptrace_stop_needed(exit_code, info)) {
1495 * The arch code has something special to do before a
1496 * ptrace stop. This is allowed to block, e.g. for faults
1497 * on user stack pages. We can't keep the siglock while
1498 * calling arch_ptrace_stop, so we must release it now.
1499 * To preserve proper semantics, we must do this before
1500 * any signal bookkeeping like checking group_stop_count.
1501 * Meanwhile, a SIGKILL could come in before we retake the
1502 * siglock. That must prevent us from sleeping in TASK_TRACED.
1503 * So after regaining the lock, we must check for SIGKILL.
1505 spin_unlock_irq(¤t->sighand->siglock);
1506 arch_ptrace_stop(exit_code, info);
1507 spin_lock_irq(¤t->sighand->siglock);
1508 killed = sigkill_pending(current);
1512 * If there is a group stop in progress,
1513 * we must participate in the bookkeeping.
1515 if (current->signal->group_stop_count > 0)
1516 --current->signal->group_stop_count;
1518 current->last_siginfo = info;
1519 current->exit_code = exit_code;
1521 /* Let the debugger run. */
1522 __set_current_state(TASK_TRACED);
1523 spin_unlock_irq(¤t->sighand->siglock);
1524 read_lock(&tasklist_lock);
1525 if (!unlikely(killed) && may_ptrace_stop()) {
1526 do_notify_parent_cldstop(current, CLD_TRAPPED);
1527 read_unlock(&tasklist_lock);
1531 * By the time we got the lock, our tracer went away.
1532 * Don't drop the lock yet, another tracer may come.
1534 __set_current_state(TASK_RUNNING);
1536 current->exit_code = 0;
1537 read_unlock(&tasklist_lock);
1541 * While in TASK_TRACED, we were considered "frozen enough".
1542 * Now that we woke up, it's crucial if we're supposed to be
1543 * frozen that we freeze now before running anything substantial.
1548 * We are back. Now reacquire the siglock before touching
1549 * last_siginfo, so that we are sure to have synchronized with
1550 * any signal-sending on another CPU that wants to examine it.
1552 spin_lock_irq(¤t->sighand->siglock);
1553 current->last_siginfo = NULL;
1556 * Queued signals ignored us while we were stopped for tracing.
1557 * So check for any that we should take before resuming user mode.
1558 * This sets TIF_SIGPENDING, but never clears it.
1560 recalc_sigpending_tsk(current);
1563 void ptrace_notify(int exit_code)
1567 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1569 memset(&info, 0, sizeof info);
1570 info.si_signo = SIGTRAP;
1571 info.si_code = exit_code;
1572 info.si_pid = task_pid_vnr(current);
1573 info.si_uid = current->uid;
1575 /* Let the debugger run. */
1576 spin_lock_irq(¤t->sighand->siglock);
1577 ptrace_stop(exit_code, 1, &info);
1578 spin_unlock_irq(¤t->sighand->siglock);
1582 finish_stop(int stop_count)
1585 * If there are no other threads in the group, or if there is
1586 * a group stop in progress and we are the last to stop,
1587 * report to the parent. When ptraced, every thread reports itself.
1589 if (stop_count == 0 || (current->ptrace & PT_PTRACED)) {
1590 read_lock(&tasklist_lock);
1591 do_notify_parent_cldstop(current, CLD_STOPPED);
1592 read_unlock(&tasklist_lock);
1597 } while (try_to_freeze());
1599 * Now we don't run again until continued.
1601 current->exit_code = 0;
1605 * This performs the stopping for SIGSTOP and other stop signals.
1606 * We have to stop all threads in the thread group.
1607 * Returns nonzero if we've actually stopped and released the siglock.
1608 * Returns zero if we didn't stop and still hold the siglock.
1610 static int do_signal_stop(int signr)
1612 struct signal_struct *sig = current->signal;
1615 if (sig->group_stop_count > 0) {
1617 * There is a group stop in progress. We don't need to
1618 * start another one.
1620 stop_count = --sig->group_stop_count;
1622 struct task_struct *t;
1624 if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED) ||
1625 unlikely(signal_group_exit(sig)))
1628 * There is no group stop already in progress.
1629 * We must initiate one now.
1631 sig->group_exit_code = signr;
1634 for (t = next_thread(current); t != current; t = next_thread(t))
1636 * Setting state to TASK_STOPPED for a group
1637 * stop is always done with the siglock held,
1638 * so this check has no races.
1640 if (!(t->flags & PF_EXITING) &&
1641 !task_is_stopped_or_traced(t)) {
1643 signal_wake_up(t, 0);
1645 sig->group_stop_count = stop_count;
1648 if (stop_count == 0)
1649 sig->flags = SIGNAL_STOP_STOPPED;
1650 current->exit_code = sig->group_exit_code;
1651 __set_current_state(TASK_STOPPED);
1653 spin_unlock_irq(¤t->sighand->siglock);
1654 finish_stop(stop_count);
1658 static int ptrace_signal(int signr, siginfo_t *info,
1659 struct pt_regs *regs, void *cookie)
1661 if (!(current->ptrace & PT_PTRACED))
1664 ptrace_signal_deliver(regs, cookie);
1666 /* Let the debugger run. */
1667 ptrace_stop(signr, 0, info);
1669 /* We're back. Did the debugger cancel the sig? */
1670 signr = current->exit_code;
1674 current->exit_code = 0;
1676 /* Update the siginfo structure if the signal has
1677 changed. If the debugger wanted something
1678 specific in the siginfo structure then it should
1679 have updated *info via PTRACE_SETSIGINFO. */
1680 if (signr != info->si_signo) {
1681 info->si_signo = signr;
1683 info->si_code = SI_USER;
1684 info->si_pid = task_pid_vnr(current->parent);
1685 info->si_uid = current->parent->uid;
1688 /* If the (new) signal is now blocked, requeue it. */
1689 if (sigismember(¤t->blocked, signr)) {
1690 specific_send_sig_info(signr, info, current);
1697 int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
1698 struct pt_regs *regs, void *cookie)
1700 struct sighand_struct *sighand = current->sighand;
1701 struct signal_struct *signal = current->signal;
1706 * We'll jump back here after any time we were stopped in TASK_STOPPED.
1707 * While in TASK_STOPPED, we were considered "frozen enough".
1708 * Now that we woke up, it's crucial if we're supposed to be
1709 * frozen that we freeze now before running anything substantial.
1713 spin_lock_irq(&sighand->siglock);
1715 if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
1716 int why = (signal->flags & SIGNAL_STOP_CONTINUED)
1717 ? CLD_CONTINUED : CLD_STOPPED;
1718 signal->flags &= ~SIGNAL_CLD_MASK;
1719 spin_unlock_irq(&sighand->siglock);
1721 read_lock(&tasklist_lock);
1722 do_notify_parent_cldstop(current->group_leader, why);
1723 read_unlock(&tasklist_lock);
1728 struct k_sigaction *ka;
1730 if (unlikely(signal->group_stop_count > 0) &&
1734 signr = dequeue_signal(current, ¤t->blocked, info);
1736 break; /* will return 0 */
1738 if (signr != SIGKILL) {
1739 signr = ptrace_signal(signr, info, regs, cookie);
1744 ka = &sighand->action[signr-1];
1745 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
1747 if (ka->sa.sa_handler != SIG_DFL) {
1748 /* Run the handler. */
1751 if (ka->sa.sa_flags & SA_ONESHOT)
1752 ka->sa.sa_handler = SIG_DFL;
1754 break; /* will return non-zero "signr" value */
1758 * Now we are doing the default action for this signal.
1760 if (sig_kernel_ignore(signr)) /* Default is nothing. */
1764 * Global init gets no signals it doesn't want.
1766 if (is_global_init(current))
1769 if (sig_kernel_stop(signr)) {
1771 * The default action is to stop all threads in
1772 * the thread group. The job control signals
1773 * do nothing in an orphaned pgrp, but SIGSTOP
1774 * always works. Note that siglock needs to be
1775 * dropped during the call to is_orphaned_pgrp()
1776 * because of lock ordering with tasklist_lock.
1777 * This allows an intervening SIGCONT to be posted.
1778 * We need to check for that and bail out if necessary.
1780 if (signr != SIGSTOP) {
1781 spin_unlock_irq(&sighand->siglock);
1783 /* signals can be posted during this window */
1785 if (is_current_pgrp_orphaned())
1788 spin_lock_irq(&sighand->siglock);
1791 if (likely(do_signal_stop(signr))) {
1792 /* It released the siglock. */
1797 * We didn't actually stop, due to a race
1798 * with SIGCONT or something like that.
1803 spin_unlock_irq(&sighand->siglock);
1806 * Anything else is fatal, maybe with a core dump.
1808 current->flags |= PF_SIGNALED;
1809 if ((signr != SIGKILL) && print_fatal_signals)
1810 print_fatal_signal(regs, signr);
1811 if (sig_kernel_coredump(signr)) {
1813 * If it was able to dump core, this kills all
1814 * other threads in the group and synchronizes with
1815 * their demise. If we lost the race with another
1816 * thread getting here, it set group_exit_code
1817 * first and our do_group_exit call below will use
1818 * that value and ignore the one we pass it.
1820 do_coredump((long)signr, signr, regs);
1824 * Death signals, no core dump.
1826 do_group_exit(signr);
1829 spin_unlock_irq(&sighand->siglock);
1833 void exit_signals(struct task_struct *tsk)
1836 struct task_struct *t;
1838 if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
1839 tsk->flags |= PF_EXITING;
1843 spin_lock_irq(&tsk->sighand->siglock);
1845 * From now this task is not visible for group-wide signals,
1846 * see wants_signal(), do_signal_stop().
1848 tsk->flags |= PF_EXITING;
1849 if (!signal_pending(tsk))
1852 /* It could be that __group_complete_signal() choose us to
1853 * notify about group-wide signal. Another thread should be
1854 * woken now to take the signal since we will not.
1856 for (t = tsk; (t = next_thread(t)) != tsk; )
1857 if (!signal_pending(t) && !(t->flags & PF_EXITING))
1858 recalc_sigpending_and_wake(t);
1860 if (unlikely(tsk->signal->group_stop_count) &&
1861 !--tsk->signal->group_stop_count) {
1862 tsk->signal->flags = SIGNAL_STOP_STOPPED;
1866 spin_unlock_irq(&tsk->sighand->siglock);
1868 if (unlikely(group_stop)) {
1869 read_lock(&tasklist_lock);
1870 do_notify_parent_cldstop(tsk, CLD_STOPPED);
1871 read_unlock(&tasklist_lock);
1875 EXPORT_SYMBOL(recalc_sigpending);
1876 EXPORT_SYMBOL_GPL(dequeue_signal);
1877 EXPORT_SYMBOL(flush_signals);
1878 EXPORT_SYMBOL(force_sig);
1879 EXPORT_SYMBOL(kill_proc);
1880 EXPORT_SYMBOL(ptrace_notify);
1881 EXPORT_SYMBOL(send_sig);
1882 EXPORT_SYMBOL(send_sig_info);
1883 EXPORT_SYMBOL(sigprocmask);
1884 EXPORT_SYMBOL(block_all_signals);
1885 EXPORT_SYMBOL(unblock_all_signals);
1889 * System call entry points.
1892 asmlinkage long sys_restart_syscall(void)
1894 struct restart_block *restart = ¤t_thread_info()->restart_block;
1895 return restart->fn(restart);
1898 long do_no_restart_syscall(struct restart_block *param)
1904 * We don't need to get the kernel lock - this is all local to this
1905 * particular thread.. (and that's good, because this is _heavily_
1906 * used by various programs)
1910 * This is also useful for kernel threads that want to temporarily
1911 * (or permanently) block certain signals.
1913 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
1914 * interface happily blocks "unblockable" signals like SIGKILL
1917 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
1921 spin_lock_irq(¤t->sighand->siglock);
1923 *oldset = current->blocked;
1928 sigorsets(¤t->blocked, ¤t->blocked, set);
1931 signandsets(¤t->blocked, ¤t->blocked, set);
1934 current->blocked = *set;
1939 recalc_sigpending();
1940 spin_unlock_irq(¤t->sighand->siglock);
1946 sys_rt_sigprocmask(int how, sigset_t __user *set, sigset_t __user *oset, size_t sigsetsize)
1948 int error = -EINVAL;
1949 sigset_t old_set, new_set;
1951 /* XXX: Don't preclude handling different sized sigset_t's. */
1952 if (sigsetsize != sizeof(sigset_t))
1957 if (copy_from_user(&new_set, set, sizeof(*set)))
1959 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
1961 error = sigprocmask(how, &new_set, &old_set);
1967 spin_lock_irq(¤t->sighand->siglock);
1968 old_set = current->blocked;
1969 spin_unlock_irq(¤t->sighand->siglock);
1973 if (copy_to_user(oset, &old_set, sizeof(*oset)))
1981 long do_sigpending(void __user *set, unsigned long sigsetsize)
1983 long error = -EINVAL;
1986 if (sigsetsize > sizeof(sigset_t))
1989 spin_lock_irq(¤t->sighand->siglock);
1990 sigorsets(&pending, ¤t->pending.signal,
1991 ¤t->signal->shared_pending.signal);
1992 spin_unlock_irq(¤t->sighand->siglock);
1994 /* Outside the lock because only this thread touches it. */
1995 sigandsets(&pending, ¤t->blocked, &pending);
1998 if (!copy_to_user(set, &pending, sigsetsize))
2006 sys_rt_sigpending(sigset_t __user *set, size_t sigsetsize)
2008 return do_sigpending(set, sigsetsize);
2011 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2013 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2017 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2019 if (from->si_code < 0)
2020 return __copy_to_user(to, from, sizeof(siginfo_t))
2023 * If you change siginfo_t structure, please be sure
2024 * this code is fixed accordingly.
2025 * Please remember to update the signalfd_copyinfo() function
2026 * inside fs/signalfd.c too, in case siginfo_t changes.
2027 * It should never copy any pad contained in the structure
2028 * to avoid security leaks, but must copy the generic
2029 * 3 ints plus the relevant union member.
2031 err = __put_user(from->si_signo, &to->si_signo);
2032 err |= __put_user(from->si_errno, &to->si_errno);
2033 err |= __put_user((short)from->si_code, &to->si_code);
2034 switch (from->si_code & __SI_MASK) {
2036 err |= __put_user(from->si_pid, &to->si_pid);
2037 err |= __put_user(from->si_uid, &to->si_uid);
2040 err |= __put_user(from->si_tid, &to->si_tid);
2041 err |= __put_user(from->si_overrun, &to->si_overrun);
2042 err |= __put_user(from->si_ptr, &to->si_ptr);
2045 err |= __put_user(from->si_band, &to->si_band);
2046 err |= __put_user(from->si_fd, &to->si_fd);
2049 err |= __put_user(from->si_addr, &to->si_addr);
2050 #ifdef __ARCH_SI_TRAPNO
2051 err |= __put_user(from->si_trapno, &to->si_trapno);
2055 err |= __put_user(from->si_pid, &to->si_pid);
2056 err |= __put_user(from->si_uid, &to->si_uid);
2057 err |= __put_user(from->si_status, &to->si_status);
2058 err |= __put_user(from->si_utime, &to->si_utime);
2059 err |= __put_user(from->si_stime, &to->si_stime);
2061 case __SI_RT: /* This is not generated by the kernel as of now. */
2062 case __SI_MESGQ: /* But this is */
2063 err |= __put_user(from->si_pid, &to->si_pid);
2064 err |= __put_user(from->si_uid, &to->si_uid);
2065 err |= __put_user(from->si_ptr, &to->si_ptr);
2067 default: /* this is just in case for now ... */
2068 err |= __put_user(from->si_pid, &to->si_pid);
2069 err |= __put_user(from->si_uid, &to->si_uid);
2078 sys_rt_sigtimedwait(const sigset_t __user *uthese,
2079 siginfo_t __user *uinfo,
2080 const struct timespec __user *uts,
2089 /* XXX: Don't preclude handling different sized sigset_t's. */
2090 if (sigsetsize != sizeof(sigset_t))
2093 if (copy_from_user(&these, uthese, sizeof(these)))
2097 * Invert the set of allowed signals to get those we
2100 sigdelsetmask(&these, sigmask(SIGKILL)|sigmask(SIGSTOP));
2104 if (copy_from_user(&ts, uts, sizeof(ts)))
2106 if (ts.tv_nsec >= 1000000000L || ts.tv_nsec < 0
2111 spin_lock_irq(¤t->sighand->siglock);
2112 sig = dequeue_signal(current, &these, &info);
2114 timeout = MAX_SCHEDULE_TIMEOUT;
2116 timeout = (timespec_to_jiffies(&ts)
2117 + (ts.tv_sec || ts.tv_nsec));
2120 /* None ready -- temporarily unblock those we're
2121 * interested while we are sleeping in so that we'll
2122 * be awakened when they arrive. */
2123 current->real_blocked = current->blocked;
2124 sigandsets(¤t->blocked, ¤t->blocked, &these);
2125 recalc_sigpending();
2126 spin_unlock_irq(¤t->sighand->siglock);
2128 timeout = schedule_timeout_interruptible(timeout);
2130 spin_lock_irq(¤t->sighand->siglock);
2131 sig = dequeue_signal(current, &these, &info);
2132 current->blocked = current->real_blocked;
2133 siginitset(¤t->real_blocked, 0);
2134 recalc_sigpending();
2137 spin_unlock_irq(¤t->sighand->siglock);
2142 if (copy_siginfo_to_user(uinfo, &info))
2155 sys_kill(int pid, int sig)
2157 struct siginfo info;
2159 info.si_signo = sig;
2161 info.si_code = SI_USER;
2162 info.si_pid = task_tgid_vnr(current);
2163 info.si_uid = current->uid;
2165 return kill_something_info(sig, &info, pid);
2168 static int do_tkill(int tgid, int pid, int sig)
2171 struct siginfo info;
2172 struct task_struct *p;
2173 unsigned long flags;
2176 info.si_signo = sig;
2178 info.si_code = SI_TKILL;
2179 info.si_pid = task_tgid_vnr(current);
2180 info.si_uid = current->uid;
2183 p = find_task_by_vpid(pid);
2184 if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
2185 error = check_kill_permission(sig, &info, p);
2187 * The null signal is a permissions and process existence
2188 * probe. No signal is actually delivered.
2190 * If lock_task_sighand() fails we pretend the task dies
2191 * after receiving the signal. The window is tiny, and the
2192 * signal is private anyway.
2194 if (!error && sig && lock_task_sighand(p, &flags)) {
2195 error = specific_send_sig_info(sig, &info, p);
2196 unlock_task_sighand(p, &flags);
2205 * sys_tgkill - send signal to one specific thread
2206 * @tgid: the thread group ID of the thread
2207 * @pid: the PID of the thread
2208 * @sig: signal to be sent
2210 * This syscall also checks the @tgid and returns -ESRCH even if the PID
2211 * exists but it's not belonging to the target process anymore. This
2212 * method solves the problem of threads exiting and PIDs getting reused.
2214 asmlinkage long sys_tgkill(int tgid, int pid, int sig)
2216 /* This is only valid for single tasks */
2217 if (pid <= 0 || tgid <= 0)
2220 return do_tkill(tgid, pid, sig);
2224 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2227 sys_tkill(int pid, int sig)
2229 /* This is only valid for single tasks */
2233 return do_tkill(0, pid, sig);
2237 sys_rt_sigqueueinfo(int pid, int sig, siginfo_t __user *uinfo)
2241 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2244 /* Not even root can pretend to send signals from the kernel.
2245 Nor can they impersonate a kill(), which adds source info. */
2246 if (info.si_code >= 0)
2248 info.si_signo = sig;
2250 /* POSIX.1b doesn't mention process groups. */
2251 return kill_proc_info(sig, &info, pid);
2254 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
2256 struct task_struct *t = current;
2257 struct k_sigaction *k;
2260 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
2263 k = &t->sighand->action[sig-1];
2265 spin_lock_irq(¤t->sighand->siglock);
2270 sigdelsetmask(&act->sa.sa_mask,
2271 sigmask(SIGKILL) | sigmask(SIGSTOP));
2275 * "Setting a signal action to SIG_IGN for a signal that is
2276 * pending shall cause the pending signal to be discarded,
2277 * whether or not it is blocked."
2279 * "Setting a signal action to SIG_DFL for a signal that is
2280 * pending and whose default action is to ignore the signal
2281 * (for example, SIGCHLD), shall cause the pending signal to
2282 * be discarded, whether or not it is blocked"
2284 if (__sig_ignored(t, sig)) {
2286 sigaddset(&mask, sig);
2287 rm_from_queue_full(&mask, &t->signal->shared_pending);
2289 rm_from_queue_full(&mask, &t->pending);
2291 } while (t != current);
2295 spin_unlock_irq(¤t->sighand->siglock);
2300 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
2306 oss.ss_sp = (void __user *) current->sas_ss_sp;
2307 oss.ss_size = current->sas_ss_size;
2308 oss.ss_flags = sas_ss_flags(sp);
2317 if (!access_ok(VERIFY_READ, uss, sizeof(*uss))
2318 || __get_user(ss_sp, &uss->ss_sp)
2319 || __get_user(ss_flags, &uss->ss_flags)
2320 || __get_user(ss_size, &uss->ss_size))
2324 if (on_sig_stack(sp))
2330 * Note - this code used to test ss_flags incorrectly
2331 * old code may have been written using ss_flags==0
2332 * to mean ss_flags==SS_ONSTACK (as this was the only
2333 * way that worked) - this fix preserves that older
2336 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
2339 if (ss_flags == SS_DISABLE) {
2344 if (ss_size < MINSIGSTKSZ)
2348 current->sas_ss_sp = (unsigned long) ss_sp;
2349 current->sas_ss_size = ss_size;
2354 if (copy_to_user(uoss, &oss, sizeof(oss)))
2363 #ifdef __ARCH_WANT_SYS_SIGPENDING
2366 sys_sigpending(old_sigset_t __user *set)
2368 return do_sigpending(set, sizeof(*set));
2373 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
2374 /* Some platforms have their own version with special arguments others
2375 support only sys_rt_sigprocmask. */
2378 sys_sigprocmask(int how, old_sigset_t __user *set, old_sigset_t __user *oset)
2381 old_sigset_t old_set, new_set;
2385 if (copy_from_user(&new_set, set, sizeof(*set)))
2387 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
2389 spin_lock_irq(¤t->sighand->siglock);
2390 old_set = current->blocked.sig[0];
2398 sigaddsetmask(¤t->blocked, new_set);
2401 sigdelsetmask(¤t->blocked, new_set);
2404 current->blocked.sig[0] = new_set;
2408 recalc_sigpending();
2409 spin_unlock_irq(¤t->sighand->siglock);
2415 old_set = current->blocked.sig[0];
2418 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2425 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
2427 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
2429 sys_rt_sigaction(int sig,
2430 const struct sigaction __user *act,
2431 struct sigaction __user *oact,
2434 struct k_sigaction new_sa, old_sa;
2437 /* XXX: Don't preclude handling different sized sigset_t's. */
2438 if (sigsetsize != sizeof(sigset_t))
2442 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
2446 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
2449 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
2455 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
2457 #ifdef __ARCH_WANT_SYS_SGETMASK
2460 * For backwards compatibility. Functionality superseded by sigprocmask.
2466 return current->blocked.sig[0];
2470 sys_ssetmask(int newmask)
2474 spin_lock_irq(¤t->sighand->siglock);
2475 old = current->blocked.sig[0];
2477 siginitset(¤t->blocked, newmask & ~(sigmask(SIGKILL)|
2479 recalc_sigpending();
2480 spin_unlock_irq(¤t->sighand->siglock);
2484 #endif /* __ARCH_WANT_SGETMASK */
2486 #ifdef __ARCH_WANT_SYS_SIGNAL
2488 * For backwards compatibility. Functionality superseded by sigaction.
2490 asmlinkage unsigned long
2491 sys_signal(int sig, __sighandler_t handler)
2493 struct k_sigaction new_sa, old_sa;
2496 new_sa.sa.sa_handler = handler;
2497 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
2498 sigemptyset(&new_sa.sa.sa_mask);
2500 ret = do_sigaction(sig, &new_sa, &old_sa);
2502 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
2504 #endif /* __ARCH_WANT_SYS_SIGNAL */
2506 #ifdef __ARCH_WANT_SYS_PAUSE
2511 current->state = TASK_INTERRUPTIBLE;
2513 return -ERESTARTNOHAND;
2518 #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
2519 asmlinkage long sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize)
2523 /* XXX: Don't preclude handling different sized sigset_t's. */
2524 if (sigsetsize != sizeof(sigset_t))
2527 if (copy_from_user(&newset, unewset, sizeof(newset)))
2529 sigdelsetmask(&newset, sigmask(SIGKILL)|sigmask(SIGSTOP));
2531 spin_lock_irq(¤t->sighand->siglock);
2532 current->saved_sigmask = current->blocked;
2533 current->blocked = newset;
2534 recalc_sigpending();
2535 spin_unlock_irq(¤t->sighand->siglock);
2537 current->state = TASK_INTERRUPTIBLE;
2539 set_thread_flag(TIF_RESTORE_SIGMASK);
2540 return -ERESTARTNOHAND;
2542 #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
2544 __attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
2549 void __init signals_init(void)
2551 sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);