summaryrefslogtreecommitdiff
path: root/kernel/signal.c
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /kernel/signal.c
downloadlwn-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz
lwn-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.zip
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'kernel/signal.c')
-rw-r--r--kernel/signal.c2662
1 files changed, 2662 insertions, 0 deletions
diff --git a/kernel/signal.c b/kernel/signal.c
new file mode 100644
index 000000000000..f00a1d610f0b
--- /dev/null
+++ b/kernel/signal.c
@@ -0,0 +1,2662 @@
+/*
+ * linux/kernel/signal.c
+ *
+ * Copyright (C) 1991, 1992 Linus Torvalds
+ *
+ * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
+ *
+ * 2003-06-02 Jim Houston - Concurrent Computer Corp.
+ * Changes to use preallocated sigqueue structures
+ * to allow signals to be sent reliably.
+ */
+
+#include <linux/config.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/smp_lock.h>
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <linux/fs.h>
+#include <linux/tty.h>
+#include <linux/binfmts.h>
+#include <linux/security.h>
+#include <linux/syscalls.h>
+#include <linux/ptrace.h>
+#include <linux/posix-timers.h>
+#include <asm/param.h>
+#include <asm/uaccess.h>
+#include <asm/unistd.h>
+#include <asm/siginfo.h>
+
+/*
+ * SLAB caches for signal bits.
+ */
+
+static kmem_cache_t *sigqueue_cachep;
+
+/*
+ * In POSIX a signal is sent either to a specific thread (Linux task)
+ * or to the process as a whole (Linux thread group). How the signal
+ * is sent determines whether it's to one thread or the whole group,
+ * which determines which signal mask(s) are involved in blocking it
+ * from being delivered until later. When the signal is delivered,
+ * either it's caught or ignored by a user handler or it has a default
+ * effect that applies to the whole thread group (POSIX process).
+ *
+ * The possible effects an unblocked signal set to SIG_DFL can have are:
+ * ignore - Nothing Happens
+ * terminate - kill the process, i.e. all threads in the group,
+ * similar to exit_group. The group leader (only) reports
+ * WIFSIGNALED status to its parent.
+ * coredump - write a core dump file describing all threads using
+ * the same mm and then kill all those threads
+ * stop - stop all the threads in the group, i.e. TASK_STOPPED state
+ *
+ * SIGKILL and SIGSTOP cannot be caught, blocked, or ignored.
+ * Other signals when not blocked and set to SIG_DFL behaves as follows.
+ * The job control signals also have other special effects.
+ *
+ * +--------------------+------------------+
+ * | POSIX signal | default action |
+ * +--------------------+------------------+
+ * | SIGHUP | terminate |
+ * | SIGINT | terminate |
+ * | SIGQUIT | coredump |
+ * | SIGILL | coredump |
+ * | SIGTRAP | coredump |
+ * | SIGABRT/SIGIOT | coredump |
+ * | SIGBUS | coredump |
+ * | SIGFPE | coredump |
+ * | SIGKILL | terminate(+) |
+ * | SIGUSR1 | terminate |
+ * | SIGSEGV | coredump |
+ * | SIGUSR2 | terminate |
+ * | SIGPIPE | terminate |
+ * | SIGALRM | terminate |
+ * | SIGTERM | terminate |
+ * | SIGCHLD | ignore |
+ * | SIGCONT | ignore(*) |
+ * | SIGSTOP | stop(*)(+) |
+ * | SIGTSTP | stop(*) |
+ * | SIGTTIN | stop(*) |
+ * | SIGTTOU | stop(*) |
+ * | SIGURG | ignore |
+ * | SIGXCPU | coredump |
+ * | SIGXFSZ | coredump |
+ * | SIGVTALRM | terminate |
+ * | SIGPROF | terminate |
+ * | SIGPOLL/SIGIO | terminate |
+ * | SIGSYS/SIGUNUSED | coredump |
+ * | SIGSTKFLT | terminate |
+ * | SIGWINCH | ignore |
+ * | SIGPWR | terminate |
+ * | SIGRTMIN-SIGRTMAX | terminate |
+ * +--------------------+------------------+
+ * | non-POSIX signal | default action |
+ * +--------------------+------------------+
+ * | SIGEMT | coredump |
+ * +--------------------+------------------+
+ *
+ * (+) For SIGKILL and SIGSTOP the action is "always", not just "default".
+ * (*) Special job control effects:
+ * When SIGCONT is sent, it resumes the process (all threads in the group)
+ * from TASK_STOPPED state and also clears any pending/queued stop signals
+ * (any of those marked with "stop(*)"). This happens regardless of blocking,
+ * catching, or ignoring SIGCONT. When any stop signal is sent, it clears
+ * any pending/queued SIGCONT signals; this happens regardless of blocking,
+ * catching, or ignored the stop signal, though (except for SIGSTOP) the
+ * default action of stopping the process may happen later or never.
+ */
+
+#ifdef SIGEMT
+#define M_SIGEMT M(SIGEMT)
+#else
+#define M_SIGEMT 0
+#endif
+
+#if SIGRTMIN > BITS_PER_LONG
+#define M(sig) (1ULL << ((sig)-1))
+#else
+#define M(sig) (1UL << ((sig)-1))
+#endif
+#define T(sig, mask) (M(sig) & (mask))
+
+#define SIG_KERNEL_ONLY_MASK (\
+ M(SIGKILL) | M(SIGSTOP) )
+
+#define SIG_KERNEL_STOP_MASK (\
+ M(SIGSTOP) | M(SIGTSTP) | M(SIGTTIN) | M(SIGTTOU) )
+
+#define SIG_KERNEL_COREDUMP_MASK (\
+ M(SIGQUIT) | M(SIGILL) | M(SIGTRAP) | M(SIGABRT) | \
+ M(SIGFPE) | M(SIGSEGV) | M(SIGBUS) | M(SIGSYS) | \
+ M(SIGXCPU) | M(SIGXFSZ) | M_SIGEMT )
+
+#define SIG_KERNEL_IGNORE_MASK (\
+ M(SIGCONT) | M(SIGCHLD) | M(SIGWINCH) | M(SIGURG) )
+
+#define sig_kernel_only(sig) \
+ (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_ONLY_MASK))
+#define sig_kernel_coredump(sig) \
+ (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_COREDUMP_MASK))
+#define sig_kernel_ignore(sig) \
+ (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_IGNORE_MASK))
+#define sig_kernel_stop(sig) \
+ (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_STOP_MASK))
+
+#define sig_user_defined(t, signr) \
+ (((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_DFL) && \
+ ((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_IGN))
+
+#define sig_fatal(t, signr) \
+ (!T(signr, SIG_KERNEL_IGNORE_MASK|SIG_KERNEL_STOP_MASK) && \
+ (t)->sighand->action[(signr)-1].sa.sa_handler == SIG_DFL)
+
+static int sig_ignored(struct task_struct *t, int sig)
+{
+ void __user * handler;
+
+ /*
+ * Tracers always want to know about signals..
+ */
+ if (t->ptrace & PT_PTRACED)
+ return 0;
+
+ /*
+ * Blocked signals are never ignored, since the
+ * signal handler may change by the time it is
+ * unblocked.
+ */
+ if (sigismember(&t->blocked, sig))
+ return 0;
+
+ /* Is it explicitly or implicitly ignored? */
+ handler = t->sighand->action[sig-1].sa.sa_handler;
+ return handler == SIG_IGN ||
+ (handler == SIG_DFL && sig_kernel_ignore(sig));
+}
+
+/*
+ * Re-calculate pending state from the set of locally pending
+ * signals, globally pending signals, and blocked signals.
+ */
+static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
+{
+ unsigned long ready;
+ long i;
+
+ switch (_NSIG_WORDS) {
+ default:
+ for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
+ ready |= signal->sig[i] &~ blocked->sig[i];
+ break;
+
+ case 4: ready = signal->sig[3] &~ blocked->sig[3];
+ ready |= signal->sig[2] &~ blocked->sig[2];
+ ready |= signal->sig[1] &~ blocked->sig[1];
+ ready |= signal->sig[0] &~ blocked->sig[0];
+ break;
+
+ case 2: ready = signal->sig[1] &~ blocked->sig[1];
+ ready |= signal->sig[0] &~ blocked->sig[0];
+ break;
+
+ case 1: ready = signal->sig[0] &~ blocked->sig[0];
+ }
+ return ready != 0;
+}
+
+#define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
+
+fastcall void recalc_sigpending_tsk(struct task_struct *t)
+{
+ if (t->signal->group_stop_count > 0 ||
+ PENDING(&t->pending, &t->blocked) ||
+ PENDING(&t->signal->shared_pending, &t->blocked))
+ set_tsk_thread_flag(t, TIF_SIGPENDING);
+ else
+ clear_tsk_thread_flag(t, TIF_SIGPENDING);
+}
+
+void recalc_sigpending(void)
+{
+ recalc_sigpending_tsk(current);
+}
+
+/* Given the mask, find the first available signal that should be serviced. */
+
+static int
+next_signal(struct sigpending *pending, sigset_t *mask)
+{
+ unsigned long i, *s, *m, x;
+ int sig = 0;
+
+ s = pending->signal.sig;
+ m = mask->sig;
+ switch (_NSIG_WORDS) {
+ default:
+ for (i = 0; i < _NSIG_WORDS; ++i, ++s, ++m)
+ if ((x = *s &~ *m) != 0) {
+ sig = ffz(~x) + i*_NSIG_BPW + 1;
+ break;
+ }
+ break;
+
+ case 2: if ((x = s[0] &~ m[0]) != 0)
+ sig = 1;
+ else if ((x = s[1] &~ m[1]) != 0)
+ sig = _NSIG_BPW + 1;
+ else
+ break;
+ sig += ffz(~x);
+ break;
+
+ case 1: if ((x = *s &~ *m) != 0)
+ sig = ffz(~x) + 1;
+ break;
+ }
+
+ return sig;
+}
+
+static struct sigqueue *__sigqueue_alloc(struct task_struct *t, unsigned int __nocast flags,
+ int override_rlimit)
+{
+ struct sigqueue *q = NULL;
+
+ atomic_inc(&t->user->sigpending);
+ if (override_rlimit ||
+ atomic_read(&t->user->sigpending) <=
+ t->signal->rlim[RLIMIT_SIGPENDING].rlim_cur)
+ q = kmem_cache_alloc(sigqueue_cachep, flags);
+ if (unlikely(q == NULL)) {
+ atomic_dec(&t->user->sigpending);
+ } else {
+ INIT_LIST_HEAD(&q->list);
+ q->flags = 0;
+ q->lock = NULL;
+ q->user = get_uid(t->user);
+ }
+ return(q);
+}
+
+static inline void __sigqueue_free(struct sigqueue *q)
+{
+ if (q->flags & SIGQUEUE_PREALLOC)
+ return;
+ atomic_dec(&q->user->sigpending);
+ free_uid(q->user);
+ kmem_cache_free(sigqueue_cachep, q);
+}
+
+static void flush_sigqueue(struct sigpending *queue)
+{
+ struct sigqueue *q;
+
+ sigemptyset(&queue->signal);
+ while (!list_empty(&queue->list)) {
+ q = list_entry(queue->list.next, struct sigqueue , list);
+ list_del_init(&q->list);
+ __sigqueue_free(q);
+ }
+}
+
+/*
+ * Flush all pending signals for a task.
+ */
+
+void
+flush_signals(struct task_struct *t)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&t->sighand->siglock, flags);
+ clear_tsk_thread_flag(t,TIF_SIGPENDING);
+ flush_sigqueue(&t->pending);
+ flush_sigqueue(&t->signal->shared_pending);
+ spin_unlock_irqrestore(&t->sighand->siglock, flags);
+}
+
+/*
+ * This function expects the tasklist_lock write-locked.
+ */
+void __exit_sighand(struct task_struct *tsk)
+{
+ struct sighand_struct * sighand = tsk->sighand;
+
+ /* Ok, we're done with the signal handlers */
+ tsk->sighand = NULL;
+ if (atomic_dec_and_test(&sighand->count))
+ kmem_cache_free(sighand_cachep, sighand);
+}
+
+void exit_sighand(struct task_struct *tsk)
+{
+ write_lock_irq(&tasklist_lock);
+ __exit_sighand(tsk);
+ write_unlock_irq(&tasklist_lock);
+}
+
+/*
+ * This function expects the tasklist_lock write-locked.
+ */
+void __exit_signal(struct task_struct *tsk)
+{
+ struct signal_struct * sig = tsk->signal;
+ struct sighand_struct * sighand = tsk->sighand;
+
+ if (!sig)
+ BUG();
+ if (!atomic_read(&sig->count))
+ BUG();
+ spin_lock(&sighand->siglock);
+ posix_cpu_timers_exit(tsk);
+ if (atomic_dec_and_test(&sig->count)) {
+ posix_cpu_timers_exit_group(tsk);
+ if (tsk == sig->curr_target)
+ sig->curr_target = next_thread(tsk);
+ tsk->signal = NULL;
+ spin_unlock(&sighand->siglock);
+ flush_sigqueue(&sig->shared_pending);
+ } else {
+ /*
+ * If there is any task waiting for the group exit
+ * then notify it:
+ */
+ if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count) {
+ wake_up_process(sig->group_exit_task);
+ sig->group_exit_task = NULL;
+ }
+ if (tsk == sig->curr_target)
+ sig->curr_target = next_thread(tsk);
+ tsk->signal = NULL;
+ /*
+ * Accumulate here the counters for all threads but the
+ * group leader as they die, so they can be added into
+ * the process-wide totals when those are taken.
+ * The group leader stays around as a zombie as long
+ * as there are other threads. When it gets reaped,
+ * the exit.c code will add its counts into these totals.
+ * We won't ever get here for the group leader, since it
+ * will have been the last reference on the signal_struct.
+ */
+ sig->utime = cputime_add(sig->utime, tsk->utime);
+ sig->stime = cputime_add(sig->stime, tsk->stime);
+ sig->min_flt += tsk->min_flt;
+ sig->maj_flt += tsk->maj_flt;
+ sig->nvcsw += tsk->nvcsw;
+ sig->nivcsw += tsk->nivcsw;
+ sig->sched_time += tsk->sched_time;
+ spin_unlock(&sighand->siglock);
+ sig = NULL; /* Marker for below. */
+ }
+ clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
+ flush_sigqueue(&tsk->pending);
+ if (sig) {
+ /*
+ * We are cleaning up the signal_struct here. We delayed
+ * calling exit_itimers until after flush_sigqueue, just in
+ * case our thread-local pending queue contained a queued
+ * timer signal that would have been cleared in
+ * exit_itimers. When that called sigqueue_free, it would
+ * attempt to re-take the tasklist_lock and deadlock. This
+ * can never happen if we ensure that all queues the
+ * timer's signal might be queued on have been flushed
+ * first. The shared_pending queue, and our own pending
+ * queue are the only queues the timer could be on, since
+ * there are no other threads left in the group and timer
+ * signals are constrained to threads inside the group.
+ */
+ exit_itimers(sig);
+ exit_thread_group_keys(sig);
+ kmem_cache_free(signal_cachep, sig);
+ }
+}
+
+void exit_signal(struct task_struct *tsk)
+{
+ write_lock_irq(&tasklist_lock);
+ __exit_signal(tsk);
+ write_unlock_irq(&tasklist_lock);
+}
+
+/*
+ * Flush all handlers for a task.
+ */
+
+void
+flush_signal_handlers(struct task_struct *t, int force_default)
+{
+ int i;
+ struct k_sigaction *ka = &t->sighand->action[0];
+ for (i = _NSIG ; i != 0 ; i--) {
+ if (force_default || ka->sa.sa_handler != SIG_IGN)
+ ka->sa.sa_handler = SIG_DFL;
+ ka->sa.sa_flags = 0;
+ sigemptyset(&ka->sa.sa_mask);
+ ka++;
+ }
+}
+
+
+/* Notify the system that a driver wants to block all signals for this
+ * process, and wants to be notified if any signals at all were to be
+ * sent/acted upon. If the notifier routine returns non-zero, then the
+ * signal will be acted upon after all. If the notifier routine returns 0,
+ * then then signal will be blocked. Only one block per process is
+ * allowed. priv is a pointer to private data that the notifier routine
+ * can use to determine if the signal should be blocked or not. */
+
+void
+block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&current->sighand->siglock, flags);
+ current->notifier_mask = mask;
+ current->notifier_data = priv;
+ current->notifier = notifier;
+ spin_unlock_irqrestore(&current->sighand->siglock, flags);
+}
+
+/* Notify the system that blocking has ended. */
+
+void
+unblock_all_signals(void)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&current->sighand->siglock, flags);
+ current->notifier = NULL;
+ current->notifier_data = NULL;
+ recalc_sigpending();
+ spin_unlock_irqrestore(&current->sighand->siglock, flags);
+}
+
+static inline int collect_signal(int sig, struct sigpending *list, siginfo_t *info)
+{
+ struct sigqueue *q, *first = NULL;
+ int still_pending = 0;
+
+ if (unlikely(!sigismember(&list->signal, sig)))
+ return 0;
+
+ /*
+ * Collect the siginfo appropriate to this signal. Check if
+ * there is another siginfo for the same signal.
+ */
+ list_for_each_entry(q, &list->list, list) {
+ if (q->info.si_signo == sig) {
+ if (first) {
+ still_pending = 1;
+ break;
+ }
+ first = q;
+ }
+ }
+ if (first) {
+ list_del_init(&first->list);
+ copy_siginfo(info, &first->info);
+ __sigqueue_free(first);
+ if (!still_pending)
+ sigdelset(&list->signal, sig);
+ } else {
+
+ /* Ok, it wasn't in the queue. This must be
+ a fast-pathed signal or we must have been
+ out of queue space. So zero out the info.
+ */
+ sigdelset(&list->signal, sig);
+ info->si_signo = sig;
+ info->si_errno = 0;
+ info->si_code = 0;
+ info->si_pid = 0;
+ info->si_uid = 0;
+ }
+ return 1;
+}
+
+static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
+ siginfo_t *info)
+{
+ int sig = 0;
+
+ sig = next_signal(pending, mask);
+ if (sig) {
+ if (current->notifier) {
+ if (sigismember(current->notifier_mask, sig)) {
+ if (!(current->notifier)(current->notifier_data)) {
+ clear_thread_flag(TIF_SIGPENDING);
+ return 0;
+ }
+ }
+ }
+
+ if (!collect_signal(sig, pending, info))
+ sig = 0;
+
+ }
+ recalc_sigpending();
+
+ return sig;
+}
+
+/*
+ * Dequeue a signal and return the element to the caller, which is
+ * expected to free it.
+ *
+ * All callers have to hold the siglock.
+ */
+int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
+{
+ int signr = __dequeue_signal(&tsk->pending, mask, info);
+ if (!signr)
+ signr = __dequeue_signal(&tsk->signal->shared_pending,
+ mask, info);
+ if (signr && unlikely(sig_kernel_stop(signr))) {
+ /*
+ * Set a marker that we have dequeued a stop signal. Our
+ * caller might release the siglock and then the pending
+ * stop signal it is about to process is no longer in the
+ * pending bitmasks, but must still be cleared by a SIGCONT
+ * (and overruled by a SIGKILL). So those cases clear this
+ * shared flag after we've set it. Note that this flag may
+ * remain set after the signal we return is ignored or
+ * handled. That doesn't matter because its only purpose
+ * is to alert stop-signal processing code when another
+ * processor has come along and cleared the flag.
+ */
+ tsk->signal->flags |= SIGNAL_STOP_DEQUEUED;
+ }
+ if ( signr &&
+ ((info->si_code & __SI_MASK) == __SI_TIMER) &&
+ info->si_sys_private){
+ /*
+ * Release the siglock to ensure proper locking order
+ * of timer locks outside of siglocks. Note, we leave
+ * irqs disabled here, since the posix-timers code is
+ * about to disable them again anyway.
+ */
+ spin_unlock(&tsk->sighand->siglock);
+ do_schedule_next_timer(info);
+ spin_lock(&tsk->sighand->siglock);
+ }
+ return signr;
+}
+
+/*
+ * Tell a process that it has a new active signal..
+ *
+ * NOTE! we rely on the previous spin_lock to
+ * lock interrupts for us! We can only be called with
+ * "siglock" held, and the local interrupt must
+ * have been disabled when that got acquired!
+ *
+ * No need to set need_resched since signal event passing
+ * goes through ->blocked
+ */
+void signal_wake_up(struct task_struct *t, int resume)
+{
+ unsigned int mask;
+
+ set_tsk_thread_flag(t, TIF_SIGPENDING);
+
+ /*
+ * For SIGKILL, we want to wake it up in the stopped/traced case.
+ * We don't check t->state here because there is a race with it
+ * executing another processor and just now entering stopped state.
+ * By using wake_up_state, we ensure the process will wake up and
+ * handle its death signal.
+ */
+ mask = TASK_INTERRUPTIBLE;
+ if (resume)
+ mask |= TASK_STOPPED | TASK_TRACED;
+ if (!wake_up_state(t, mask))
+ kick_process(t);
+}
+
+/*
+ * Remove signals in mask from the pending set and queue.
+ * Returns 1 if any signals were found.
+ *
+ * All callers must be holding the siglock.
+ */
+static int rm_from_queue(unsigned long mask, struct sigpending *s)
+{
+ struct sigqueue *q, *n;
+
+ if (!sigtestsetmask(&s->signal, mask))
+ return 0;
+
+ sigdelsetmask(&s->signal, mask);
+ list_for_each_entry_safe(q, n, &s->list, list) {
+ if (q->info.si_signo < SIGRTMIN &&
+ (mask & sigmask(q->info.si_signo))) {
+ list_del_init(&q->list);
+ __sigqueue_free(q);
+ }
+ }
+ return 1;
+}
+
+/*
+ * Bad permissions for sending the signal
+ */
+static int check_kill_permission(int sig, struct siginfo *info,
+ struct task_struct *t)
+{
+ int error = -EINVAL;
+ if (sig < 0 || sig > _NSIG)
+ return error;
+ error = -EPERM;
+ if ((!info || ((unsigned long)info != 1 &&
+ (unsigned long)info != 2 && SI_FROMUSER(info)))
+ && ((sig != SIGCONT) ||
+ (current->signal->session != t->signal->session))
+ && (current->euid ^ t->suid) && (current->euid ^ t->uid)
+ && (current->uid ^ t->suid) && (current->uid ^ t->uid)
+ && !capable(CAP_KILL))
+ return error;
+ return security_task_kill(t, info, sig);
+}
+
+/* forward decl */
+static void do_notify_parent_cldstop(struct task_struct *tsk,
+ struct task_struct *parent,
+ int why);
+
+/*
+ * Handle magic process-wide effects of stop/continue signals.
+ * Unlike the signal actions, these happen immediately at signal-generation
+ * time regardless of blocking, ignoring, or handling. This does the
+ * actual continuing for SIGCONT, but not the actual stopping for stop
+ * signals. The process stop is done as a signal action for SIG_DFL.
+ */
+static void handle_stop_signal(int sig, struct task_struct *p)
+{
+ struct task_struct *t;
+
+ if (p->flags & SIGNAL_GROUP_EXIT)
+ /*
+ * The process is in the middle of dying already.
+ */
+ return;
+
+ if (sig_kernel_stop(sig)) {
+ /*
+ * This is a stop signal. Remove SIGCONT from all queues.
+ */
+ rm_from_queue(sigmask(SIGCONT), &p->signal->shared_pending);
+ t = p;
+ do {
+ rm_from_queue(sigmask(SIGCONT), &t->pending);
+ t = next_thread(t);
+ } while (t != p);
+ } else if (sig == SIGCONT) {
+ /*
+ * Remove all stop signals from all queues,
+ * and wake all threads.
+ */
+ if (unlikely(p->signal->group_stop_count > 0)) {
+ /*
+ * There was a group stop in progress. We'll
+ * pretend it finished before we got here. We are
+ * obliged to report it to the parent: if the
+ * SIGSTOP happened "after" this SIGCONT, then it
+ * would have cleared this pending SIGCONT. If it
+ * happened "before" this SIGCONT, then the parent
+ * got the SIGCHLD about the stop finishing before
+ * the continue happened. We do the notification
+ * now, and it's as if the stop had finished and
+ * the SIGCHLD was pending on entry to this kill.
+ */
+ p->signal->group_stop_count = 0;
+ p->signal->flags = SIGNAL_STOP_CONTINUED;
+ spin_unlock(&p->sighand->siglock);
+ if (p->ptrace & PT_PTRACED)
+ do_notify_parent_cldstop(p, p->parent,
+ CLD_STOPPED);
+ else
+ do_notify_parent_cldstop(
+ p->group_leader,
+ p->group_leader->real_parent,
+ CLD_STOPPED);
+ spin_lock(&p->sighand->siglock);
+ }
+ rm_from_queue(SIG_KERNEL_STOP_MASK, &p->signal->shared_pending);
+ t = p;
+ do {
+ unsigned int state;
+ rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
+
+ /*
+ * If there is a handler for SIGCONT, we must make
+ * sure that no thread returns to user mode before
+ * we post the signal, in case it was the only
+ * thread eligible to run the signal handler--then
+ * it must not do anything between resuming and
+ * running the handler. With the TIF_SIGPENDING
+ * flag set, the thread will pause and acquire the
+ * siglock that we hold now and until we've queued
+ * the pending signal.
+ *
+ * Wake up the stopped thread _after_ setting
+ * TIF_SIGPENDING
+ */
+ state = TASK_STOPPED;
+ if (sig_user_defined(t, SIGCONT) && !sigismember(&t->blocked, SIGCONT)) {
+ set_tsk_thread_flag(t, TIF_SIGPENDING);
+ state |= TASK_INTERRUPTIBLE;
+ }
+ wake_up_state(t, state);
+
+ t = next_thread(t);
+ } while (t != p);
+
+ if (p->signal->flags & SIGNAL_STOP_STOPPED) {
+ /*
+ * We were in fact stopped, and are now continued.
+ * Notify the parent with CLD_CONTINUED.
+ */
+ p->signal->flags = SIGNAL_STOP_CONTINUED;
+ p->signal->group_exit_code = 0;
+ spin_unlock(&p->sighand->siglock);
+ if (p->ptrace & PT_PTRACED)
+ do_notify_parent_cldstop(p, p->parent,
+ CLD_CONTINUED);
+ else
+ do_notify_parent_cldstop(
+ p->group_leader,
+ p->group_leader->real_parent,
+ CLD_CONTINUED);
+ spin_lock(&p->sighand->siglock);
+ } else {
+ /*
+ * We are not stopped, but there could be a stop
+ * signal in the middle of being processed after
+ * being removed from the queue. Clear that too.
+ */
+ p->signal->flags = 0;
+ }
+ } else if (sig == SIGKILL) {
+ /*
+ * Make sure that any pending stop signal already dequeued
+ * is undone by the wakeup for SIGKILL.
+ */
+ p->signal->flags = 0;
+ }
+}
+
+static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
+ struct sigpending *signals)
+{
+ struct sigqueue * q = NULL;
+ int ret = 0;
+
+ /*
+ * fast-pathed signals for kernel-internal things like SIGSTOP
+ * or SIGKILL.
+ */
+ if ((unsigned long)info == 2)
+ goto out_set;
+
+ /* Real-time signals must be queued if sent by sigqueue, or
+ some other real-time mechanism. It is implementation
+ defined whether kill() does so. We attempt to do so, on
+ the principle of least surprise, but since kill is not
+ allowed to fail with EAGAIN when low on memory we just
+ make sure at least one signal gets delivered and don't
+ pass on the info struct. */
+
+ q = __sigqueue_alloc(t, GFP_ATOMIC, (sig < SIGRTMIN &&
+ ((unsigned long) info < 2 ||
+ info->si_code >= 0)));
+ if (q) {
+ list_add_tail(&q->list, &signals->list);
+ switch ((unsigned long) info) {
+ case 0:
+ q->info.si_signo = sig;
+ q->info.si_errno = 0;
+ q->info.si_code = SI_USER;
+ q->info.si_pid = current->pid;
+ q->info.si_uid = current->uid;
+ break;
+ case 1:
+ q->info.si_signo = sig;
+ q->info.si_errno = 0;
+ q->info.si_code = SI_KERNEL;
+ q->info.si_pid = 0;
+ q->info.si_uid = 0;
+ break;
+ default:
+ copy_siginfo(&q->info, info);
+ break;
+ }
+ } else {
+ if (sig >= SIGRTMIN && info && (unsigned long)info != 1
+ && info->si_code != SI_USER)
+ /*
+ * Queue overflow, abort. We may abort if the signal was rt
+ * and sent by user using something other than kill().
+ */
+ return -EAGAIN;
+ if (((unsigned long)info > 1) && (info->si_code == SI_TIMER))
+ /*
+ * Set up a return to indicate that we dropped
+ * the signal.
+ */
+ ret = info->si_sys_private;
+ }
+
+out_set:
+ sigaddset(&signals->signal, sig);
+ return ret;
+}
+
+#define LEGACY_QUEUE(sigptr, sig) \
+ (((sig) < SIGRTMIN) && sigismember(&(sigptr)->signal, (sig)))
+
+
+static int
+specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
+{
+ int ret = 0;
+
+ if (!irqs_disabled())
+ BUG();
+ assert_spin_locked(&t->sighand->siglock);
+
+ if (((unsigned long)info > 2) && (info->si_code == SI_TIMER))
+ /*
+ * Set up a return to indicate that we dropped the signal.
+ */
+ ret = info->si_sys_private;
+
+ /* Short-circuit ignored signals. */
+ if (sig_ignored(t, sig))
+ goto out;
+
+ /* Support queueing exactly one non-rt signal, so that we
+ can get more detailed information about the cause of
+ the signal. */
+ if (LEGACY_QUEUE(&t->pending, sig))
+ goto out;
+
+ ret = send_signal(sig, info, t, &t->pending);
+ if (!ret && !sigismember(&t->blocked, sig))
+ signal_wake_up(t, sig == SIGKILL);
+out:
+ return ret;
+}
+
+/*
+ * Force a signal that the process can't ignore: if necessary
+ * we unblock the signal and change any SIG_IGN to SIG_DFL.
+ */
+
+int
+force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
+{
+ unsigned long int flags;
+ int ret;
+
+ spin_lock_irqsave(&t->sighand->siglock, flags);
+ if (sigismember(&t->blocked, sig) || t->sighand->action[sig-1].sa.sa_handler == SIG_IGN) {
+ t->sighand->action[sig-1].sa.sa_handler = SIG_DFL;
+ sigdelset(&t->blocked, sig);
+ recalc_sigpending_tsk(t);
+ }
+ ret = specific_send_sig_info(sig, info, t);
+ spin_unlock_irqrestore(&t->sighand->siglock, flags);
+
+ return ret;
+}
+
+void
+force_sig_specific(int sig, struct task_struct *t)
+{
+ unsigned long int flags;
+
+ spin_lock_irqsave(&t->sighand->siglock, flags);
+ if (t->sighand->action[sig-1].sa.sa_handler == SIG_IGN)
+ t->sighand->action[sig-1].sa.sa_handler = SIG_DFL;
+ sigdelset(&t->blocked, sig);
+ recalc_sigpending_tsk(t);
+ specific_send_sig_info(sig, (void *)2, t);
+ spin_unlock_irqrestore(&t->sighand->siglock, flags);
+}
+
+/*
+ * Test if P wants to take SIG. After we've checked all threads with this,
+ * it's equivalent to finding no threads not blocking SIG. Any threads not
+ * blocking SIG were ruled out because they are not running and already
+ * have pending signals. Such threads will dequeue from the shared queue
+ * as soon as they're available, so putting the signal on the shared queue
+ * will be equivalent to sending it to one such thread.
+ */
+#define wants_signal(sig, p, mask) \
+ (!sigismember(&(p)->blocked, sig) \
+ && !((p)->state & mask) \
+ && !((p)->flags & PF_EXITING) \
+ && (task_curr(p) || !signal_pending(p)))
+
+
+static void
+__group_complete_signal(int sig, struct task_struct *p)
+{
+ unsigned int mask;
+ struct task_struct *t;
+
+ /*
+ * Don't bother traced and stopped tasks (but
+ * SIGKILL will punch through that).
+ */
+ mask = TASK_STOPPED | TASK_TRACED;
+ if (sig == SIGKILL)
+ mask = 0;
+
+ /*
+ * Now find a thread we can wake up to take the signal off the queue.
+ *
+ * If the main thread wants the signal, it gets first crack.
+ * Probably the least surprising to the average bear.
+ */
+ if (wants_signal(sig, p, mask))
+ t = p;
+ else if (thread_group_empty(p))
+ /*
+ * There is just one thread and it does not need to be woken.
+ * It will dequeue unblocked signals before it runs again.
+ */
+ return;
+ else {
+ /*
+ * Otherwise try to find a suitable thread.
+ */
+ t = p->signal->curr_target;
+ if (t == NULL)
+ /* restart balancing at this thread */
+ t = p->signal->curr_target = p;
+ BUG_ON(t->tgid != p->tgid);
+
+ while (!wants_signal(sig, t, mask)) {
+ t = next_thread(t);
+ if (t == p->signal->curr_target)
+ /*
+ * No thread needs to be woken.
+ * Any eligible threads will see
+ * the signal in the queue soon.
+ */
+ return;
+ }
+ p->signal->curr_target = t;
+ }
+
+ /*
+ * Found a killable thread. If the signal will be fatal,
+ * then start taking the whole group down immediately.
+ */
+ if (sig_fatal(p, sig) && !(p->signal->flags & SIGNAL_GROUP_EXIT) &&
+ !sigismember(&t->real_blocked, sig) &&
+ (sig == SIGKILL || !(t->ptrace & PT_PTRACED))) {
+ /*
+ * This signal will be fatal to the whole group.
+ */
+ if (!sig_kernel_coredump(sig)) {
+ /*
+ * Start a group exit and wake everybody up.
+ * This way we don't have other threads
+ * running and doing things after a slower
+ * thread has the fatal signal pending.
+ */
+ p->signal->flags = SIGNAL_GROUP_EXIT;
+ p->signal->group_exit_code = sig;
+ p->signal->group_stop_count = 0;
+ t = p;
+ do {
+ sigaddset(&t->pending.signal, SIGKILL);
+ signal_wake_up(t, 1);
+ t = next_thread(t);
+ } while (t != p);
+ return;
+ }
+
+ /*
+ * There will be a core dump. We make all threads other
+ * than the chosen one go into a group stop so that nothing
+ * happens until it gets scheduled, takes the signal off
+ * the shared queue, and does the core dump. This is a
+ * little more complicated than strictly necessary, but it
+ * keeps the signal state that winds up in the core dump
+ * unchanged from the death state, e.g. which thread had
+ * the core-dump signal unblocked.
+ */
+ rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
+ rm_from_queue(SIG_KERNEL_STOP_MASK, &p->signal->shared_pending);
+ p->signal->group_stop_count = 0;
+ p->signal->group_exit_task = t;
+ t = p;
+ do {
+ p->signal->group_stop_count++;
+ signal_wake_up(t, 0);
+ t = next_thread(t);
+ } while (t != p);
+ wake_up_process(p->signal->group_exit_task);
+ return;
+ }
+
+ /*
+ * The signal is already in the shared-pending queue.
+ * Tell the chosen thread to wake up and dequeue it.
+ */
+ signal_wake_up(t, sig == SIGKILL);
+ return;
+}
+
+int
+__group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
+{
+ int ret = 0;
+
+ assert_spin_locked(&p->sighand->siglock);
+ handle_stop_signal(sig, p);
+
+ if (((unsigned long)info > 2) && (info->si_code == SI_TIMER))
+ /*
+ * Set up a return to indicate that we dropped the signal.
+ */
+ ret = info->si_sys_private;
+
+ /* Short-circuit ignored signals. */
+ if (sig_ignored(p, sig))
+ return ret;
+
+ if (LEGACY_QUEUE(&p->signal->shared_pending, sig))
+ /* This is a non-RT signal and we already have one queued. */
+ return ret;
+
+ /*
+ * Put this signal on the shared-pending queue, or fail with EAGAIN.
+ * We always use the shared queue for process-wide signals,
+ * to avoid several races.
+ */
+ ret = send_signal(sig, info, p, &p->signal->shared_pending);
+ if (unlikely(ret))
+ return ret;
+
+ __group_complete_signal(sig, p);
+ return 0;
+}
+
+/*
+ * Nuke all other threads in the group.
+ */
+void zap_other_threads(struct task_struct *p)
+{
+ struct task_struct *t;
+
+ p->signal->flags = SIGNAL_GROUP_EXIT;
+ p->signal->group_stop_count = 0;
+
+ if (thread_group_empty(p))
+ return;
+
+ for (t = next_thread(p); t != p; t = next_thread(t)) {
+ /*
+ * Don't bother with already dead threads
+ */
+ if (t->exit_state)
+ continue;
+
+ /*
+ * We don't want to notify the parent, since we are
+ * killed as part of a thread group due to another
+ * thread doing an execve() or similar. So set the
+ * exit signal to -1 to allow immediate reaping of
+ * the process. But don't detach the thread group
+ * leader.
+ */
+ if (t != p->group_leader)
+ t->exit_signal = -1;
+
+ sigaddset(&t->pending.signal, SIGKILL);
+ rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
+ signal_wake_up(t, 1);
+ }
+}
+
+/*
+ * Must be called with the tasklist_lock held for reading!
+ */
+int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
+{
+ unsigned long flags;
+ int ret;
+
+ ret = check_kill_permission(sig, info, p);
+ if (!ret && sig && p->sighand) {
+ spin_lock_irqsave(&p->sighand->siglock, flags);
+ ret = __group_send_sig_info(sig, info, p);
+ spin_unlock_irqrestore(&p->sighand->siglock, flags);
+ }
+
+ return ret;
+}
+
+/*
+ * kill_pg_info() sends a signal to a process group: this is what the tty
+ * control characters do (^C, ^Z etc)
+ */
+
+int __kill_pg_info(int sig, struct siginfo *info, pid_t pgrp)
+{
+ struct task_struct *p = NULL;
+ int retval, success;
+
+ if (pgrp <= 0)
+ return -EINVAL;
+
+ success = 0;
+ retval = -ESRCH;
+ do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
+ int err = group_send_sig_info(sig, info, p);
+ success |= !err;
+ retval = err;
+ } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
+ return success ? 0 : retval;
+}
+
+int
+kill_pg_info(int sig, struct siginfo *info, pid_t pgrp)
+{
+ int retval;
+
+ read_lock(&tasklist_lock);
+ retval = __kill_pg_info(sig, info, pgrp);
+ read_unlock(&tasklist_lock);
+
+ return retval;
+}
+
+int
+kill_proc_info(int sig, struct siginfo *info, pid_t pid)
+{
+ int error;
+ struct task_struct *p;
+
+ read_lock(&tasklist_lock);
+ p = find_task_by_pid(pid);
+ error = -ESRCH;
+ if (p)
+ error = group_send_sig_info(sig, info, p);
+ read_unlock(&tasklist_lock);
+ return error;
+}
+
+
+/*
+ * kill_something_info() interprets pid in interesting ways just like kill(2).
+ *
+ * POSIX specifies that kill(-1,sig) is unspecified, but what we have
+ * is probably wrong. Should make it like BSD or SYSV.
+ */
+
+static int kill_something_info(int sig, struct siginfo *info, int pid)
+{
+ if (!pid) {
+ return kill_pg_info(sig, info, process_group(current));
+ } else if (pid == -1) {
+ int retval = 0, count = 0;
+ struct task_struct * p;
+
+ read_lock(&tasklist_lock);
+ for_each_process(p) {
+ if (p->pid > 1 && p->tgid != current->tgid) {
+ int err = group_send_sig_info(sig, info, p);
+ ++count;
+ if (err != -EPERM)
+ retval = err;
+ }
+ }
+ read_unlock(&tasklist_lock);
+ return count ? retval : -ESRCH;
+ } else if (pid < 0) {
+ return kill_pg_info(sig, info, -pid);
+ } else {
+ return kill_proc_info(sig, info, pid);
+ }
+}
+
+/*
+ * These are for backward compatibility with the rest of the kernel source.
+ */
+
+/*
+ * These two are the most common entry points. They send a signal
+ * just to the specific thread.
+ */
+int
+send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
+{
+ int ret;
+ unsigned long flags;
+
+ /*
+ * Make sure legacy kernel users don't send in bad values
+ * (normal paths check this in check_kill_permission).
+ */
+ if (sig < 0 || sig > _NSIG)
+ return -EINVAL;
+
+ /*
+ * We need the tasklist lock even for the specific
+ * thread case (when we don't need to follow the group
+ * lists) in order to avoid races with "p->sighand"
+ * going away or changing from under us.
+ */
+ read_lock(&tasklist_lock);
+ spin_lock_irqsave(&p->sighand->siglock, flags);
+ ret = specific_send_sig_info(sig, info, p);
+ spin_unlock_irqrestore(&p->sighand->siglock, flags);
+ read_unlock(&tasklist_lock);
+ return ret;
+}
+
+int
+send_sig(int sig, struct task_struct *p, int priv)
+{
+ return send_sig_info(sig, (void*)(long)(priv != 0), p);
+}
+
+/*
+ * This is the entry point for "process-wide" signals.
+ * They will go to an appropriate thread in the thread group.
+ */
+int
+send_group_sig_info(int sig, struct siginfo *info, struct task_struct *p)
+{
+ int ret;
+ read_lock(&tasklist_lock);
+ ret = group_send_sig_info(sig, info, p);
+ read_unlock(&tasklist_lock);
+ return ret;
+}
+
+void
+force_sig(int sig, struct task_struct *p)
+{
+ force_sig_info(sig, (void*)1L, p);
+}
+
+/*
+ * When things go south during signal handling, we
+ * will force a SIGSEGV. And if the signal that caused
+ * the problem was already a SIGSEGV, we'll want to
+ * make sure we don't even try to deliver the signal..
+ */
+int
+force_sigsegv(int sig, struct task_struct *p)
+{
+ if (sig == SIGSEGV) {
+ unsigned long flags;
+ spin_lock_irqsave(&p->sighand->siglock, flags);
+ p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
+ spin_unlock_irqrestore(&p->sighand->siglock, flags);
+ }
+ force_sig(SIGSEGV, p);
+ return 0;
+}
+
+int
+kill_pg(pid_t pgrp, int sig, int priv)
+{
+ return kill_pg_info(sig, (void *)(long)(priv != 0), pgrp);
+}
+
+int
+kill_proc(pid_t pid, int sig, int priv)
+{
+ return kill_proc_info(sig, (void *)(long)(priv != 0), pid);
+}
+
+/*
+ * These functions support sending signals using preallocated sigqueue
+ * structures. This is needed "because realtime applications cannot
+ * afford to lose notifications of asynchronous events, like timer
+ * expirations or I/O completions". In the case of Posix Timers
+ * we allocate the sigqueue structure from the timer_create. If this
+ * allocation fails we are able to report the failure to the application
+ * with an EAGAIN error.
+ */
+
+struct sigqueue *sigqueue_alloc(void)
+{
+ struct sigqueue *q;
+
+ if ((q = __sigqueue_alloc(current, GFP_KERNEL, 0)))
+ q->flags |= SIGQUEUE_PREALLOC;
+ return(q);
+}
+
+void sigqueue_free(struct sigqueue *q)
+{
+ unsigned long flags;
+ BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
+ /*
+ * If the signal is still pending remove it from the
+ * pending queue.
+ */
+ if (unlikely(!list_empty(&q->list))) {
+ read_lock(&tasklist_lock);
+ spin_lock_irqsave(q->lock, flags);
+ if (!list_empty(&q->list))
+ list_del_init(&q->list);
+ spin_unlock_irqrestore(q->lock, flags);
+ read_unlock(&tasklist_lock);
+ }
+ q->flags &= ~SIGQUEUE_PREALLOC;
+ __sigqueue_free(q);
+}
+
+int
+send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
+{
+ unsigned long flags;
+ int ret = 0;
+
+ /*
+ * We need the tasklist lock even for the specific
+ * thread case (when we don't need to follow the group
+ * lists) in order to avoid races with "p->sighand"
+ * going away or changing from under us.
+ */
+ BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
+ read_lock(&tasklist_lock);
+ spin_lock_irqsave(&p->sighand->siglock, flags);
+
+ if (unlikely(!list_empty(&q->list))) {
+ /*
+ * If an SI_TIMER entry is already queue just increment
+ * the overrun count.
+ */
+ if (q->info.si_code != SI_TIMER)
+ BUG();
+ q->info.si_overrun++;
+ goto out;
+ }
+ /* Short-circuit ignored signals. */
+ if (sig_ignored(p, sig)) {
+ ret = 1;
+ goto out;
+ }
+
+ q->lock = &p->sighand->siglock;
+ list_add_tail(&q->list, &p->pending.list);
+ sigaddset(&p->pending.signal, sig);
+ if (!sigismember(&p->blocked, sig))
+ signal_wake_up(p, sig == SIGKILL);
+
+out:
+ spin_unlock_irqrestore(&p->sighand->siglock, flags);
+ read_unlock(&tasklist_lock);
+ return(ret);
+}
+
+int
+send_group_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
+{
+ unsigned long flags;
+ int ret = 0;
+
+ BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
+ read_lock(&tasklist_lock);
+ spin_lock_irqsave(&p->sighand->siglock, flags);
+ handle_stop_signal(sig, p);
+
+ /* Short-circuit ignored signals. */
+ if (sig_ignored(p, sig)) {
+ ret = 1;
+ goto out;
+ }
+
+ if (unlikely(!list_empty(&q->list))) {
+ /*
+ * If an SI_TIMER entry is already queue just increment
+ * the overrun count. Other uses should not try to
+ * send the signal multiple times.
+ */
+ if (q->info.si_code != SI_TIMER)
+ BUG();
+ q->info.si_overrun++;
+ goto out;
+ }
+
+ /*
+ * Put this signal on the shared-pending queue.
+ * We always use the shared queue for process-wide signals,
+ * to avoid several races.
+ */
+ q->lock = &p->sighand->siglock;
+ list_add_tail(&q->list, &p->signal->shared_pending.list);
+ sigaddset(&p->signal->shared_pending.signal, sig);
+
+ __group_complete_signal(sig, p);
+out:
+ spin_unlock_irqrestore(&p->sighand->siglock, flags);
+ read_unlock(&tasklist_lock);
+ return(ret);
+}
+
+/*
+ * Wake up any threads in the parent blocked in wait* syscalls.
+ */
+static inline void __wake_up_parent(struct task_struct *p,
+ struct task_struct *parent)
+{
+ wake_up_interruptible_sync(&parent->signal->wait_chldexit);
+}
+
+/*
+ * Let a parent know about the death of a child.
+ * For a stopped/continued status change, use do_notify_parent_cldstop instead.
+ */
+
+void do_notify_parent(struct task_struct *tsk, int sig)
+{
+ struct siginfo info;
+ unsigned long flags;
+ struct sighand_struct *psig;
+
+ BUG_ON(sig == -1);
+
+ /* do_notify_parent_cldstop should have been called instead. */
+ BUG_ON(tsk->state & (TASK_STOPPED|TASK_TRACED));
+
+ BUG_ON(!tsk->ptrace &&
+ (tsk->group_leader != tsk || !thread_group_empty(tsk)));
+
+ info.si_signo = sig;
+ info.si_errno = 0;
+ info.si_pid = tsk->pid;
+ info.si_uid = tsk->uid;
+
+ /* FIXME: find out whether or not this is supposed to be c*time. */
+ info.si_utime = cputime_to_jiffies(cputime_add(tsk->utime,
+ tsk->signal->utime));
+ info.si_stime = cputime_to_jiffies(cputime_add(tsk->stime,
+ tsk->signal->stime));
+
+ info.si_status = tsk->exit_code & 0x7f;
+ if (tsk->exit_code & 0x80)
+ info.si_code = CLD_DUMPED;
+ else if (tsk->exit_code & 0x7f)
+ info.si_code = CLD_KILLED;
+ else {
+ info.si_code = CLD_EXITED;
+ info.si_status = tsk->exit_code >> 8;
+ }
+
+ psig = tsk->parent->sighand;
+ spin_lock_irqsave(&psig->siglock, flags);
+ if (sig == SIGCHLD &&
+ (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
+ (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
+ /*
+ * We are exiting and our parent doesn't care. POSIX.1
+ * defines special semantics for setting SIGCHLD to SIG_IGN
+ * or setting the SA_NOCLDWAIT flag: we should be reaped
+ * automatically and not left for our parent's wait4 call.
+ * Rather than having the parent do it as a magic kind of
+ * signal handler, we just set this to tell do_exit that we
+ * can be cleaned up without becoming a zombie. Note that
+ * we still call __wake_up_parent in this case, because a
+ * blocked sys_wait4 might now return -ECHILD.
+ *
+ * Whether we send SIGCHLD or not for SA_NOCLDWAIT
+ * is implementation-defined: we do (if you don't want
+ * it, just use SIG_IGN instead).
+ */
+ tsk->exit_signal = -1;
+ if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
+ sig = 0;
+ }
+ if (sig > 0 && sig <= _NSIG)
+ __group_send_sig_info(sig, &info, tsk->parent);
+ __wake_up_parent(tsk, tsk->parent);
+ spin_unlock_irqrestore(&psig->siglock, flags);
+}
+
+static void
+do_notify_parent_cldstop(struct task_struct *tsk, struct task_struct *parent,
+ int why)
+{
+ struct siginfo info;
+ unsigned long flags;
+ struct sighand_struct *sighand;
+
+ info.si_signo = SIGCHLD;
+ info.si_errno = 0;
+ info.si_pid = tsk->pid;
+ info.si_uid = tsk->uid;
+
+ /* FIXME: find out whether or not this is supposed to be c*time. */
+ info.si_utime = cputime_to_jiffies(tsk->utime);
+ info.si_stime = cputime_to_jiffies(tsk->stime);
+
+ info.si_code = why;
+ switch (why) {
+ case CLD_CONTINUED:
+ info.si_status = SIGCONT;
+ break;
+ case CLD_STOPPED:
+ info.si_status = tsk->signal->group_exit_code & 0x7f;
+ break;
+ case CLD_TRAPPED:
+ info.si_status = tsk->exit_code & 0x7f;
+ break;
+ default:
+ BUG();
+ }
+
+ sighand = parent->sighand;
+ spin_lock_irqsave(&sighand->siglock, flags);
+ if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
+ !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
+ __group_send_sig_info(SIGCHLD, &info, parent);
+ /*
+ * Even if SIGCHLD is not generated, we must wake up wait4 calls.
+ */
+ __wake_up_parent(tsk, parent);
+ spin_unlock_irqrestore(&sighand->siglock, flags);
+}
+
+/*
+ * This must be called with current->sighand->siglock held.
+ *
+ * This should be the path for all ptrace stops.
+ * We always set current->last_siginfo while stopped here.
+ * That makes it a way to test a stopped process for
+ * being ptrace-stopped vs being job-control-stopped.
+ *
+ * If we actually decide not to stop at all because the tracer is gone,
+ * we leave nostop_code in current->exit_code.
+ */
+static void ptrace_stop(int exit_code, int nostop_code, siginfo_t *info)
+{
+ /*
+ * If there is a group stop in progress,
+ * we must participate in the bookkeeping.
+ */
+ if (current->signal->group_stop_count > 0)
+ --current->signal->group_stop_count;
+
+ current->last_siginfo = info;
+ current->exit_code = exit_code;
+
+ /* Let the debugger run. */
+ set_current_state(TASK_TRACED);
+ spin_unlock_irq(&current->sighand->siglock);
+ read_lock(&tasklist_lock);
+ if (likely(current->ptrace & PT_PTRACED) &&
+ likely(current->parent != current->real_parent ||
+ !(current->ptrace & PT_ATTACHED)) &&
+ (likely(current->parent->signal != current->signal) ||
+ !unlikely(current->signal->flags & SIGNAL_GROUP_EXIT))) {
+ do_notify_parent_cldstop(current, current->parent,
+ CLD_TRAPPED);
+ read_unlock(&tasklist_lock);
+ schedule();
+ } else {
+ /*
+ * By the time we got the lock, our tracer went away.
+ * Don't stop here.
+ */
+ read_unlock(&tasklist_lock);
+ set_current_state(TASK_RUNNING);
+ current->exit_code = nostop_code;
+ }
+
+ /*
+ * We are back. Now reacquire the siglock before touching
+ * last_siginfo, so that we are sure to have synchronized with
+ * any signal-sending on another CPU that wants to examine it.
+ */
+ spin_lock_irq(&current->sighand->siglock);
+ current->last_siginfo = NULL;
+
+ /*
+ * Queued signals ignored us while we were stopped for tracing.
+ * So check for any that we should take before resuming user mode.
+ */
+ recalc_sigpending();
+}
+
+void ptrace_notify(int exit_code)
+{
+ siginfo_t info;
+
+ BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
+
+ memset(&info, 0, sizeof info);
+ info.si_signo = SIGTRAP;
+ info.si_code = exit_code;
+ info.si_pid = current->pid;
+ info.si_uid = current->uid;
+
+ /* Let the debugger run. */
+ spin_lock_irq(&current->sighand->siglock);
+ ptrace_stop(exit_code, 0, &info);
+ spin_unlock_irq(&current->sighand->siglock);
+}
+
+#ifndef HAVE_ARCH_GET_SIGNAL_TO_DELIVER
+
+static void
+finish_stop(int stop_count)
+{
+ /*
+ * If there are no other threads in the group, or if there is
+ * a group stop in progress and we are the last to stop,
+ * report to the parent. When ptraced, every thread reports itself.
+ */
+ if (stop_count < 0 || (current->ptrace & PT_PTRACED)) {
+ read_lock(&tasklist_lock);
+ do_notify_parent_cldstop(current, current->parent,
+ CLD_STOPPED);
+ read_unlock(&tasklist_lock);
+ }
+ else if (stop_count == 0) {
+ read_lock(&tasklist_lock);
+ do_notify_parent_cldstop(current->group_leader,
+ current->group_leader->real_parent,
+ CLD_STOPPED);
+ read_unlock(&tasklist_lock);
+ }
+
+ schedule();
+ /*
+ * Now we don't run again until continued.
+ */
+ current->exit_code = 0;
+}
+
+/*
+ * This performs the stopping for SIGSTOP and other stop signals.
+ * We have to stop all threads in the thread group.
+ * Returns nonzero if we've actually stopped and released the siglock.
+ * Returns zero if we didn't stop and still hold the siglock.
+ */
+static int
+do_signal_stop(int signr)
+{
+ struct signal_struct *sig = current->signal;
+ struct sighand_struct *sighand = current->sighand;
+ int stop_count = -1;
+
+ if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED))
+ return 0;
+
+ if (sig->group_stop_count > 0) {
+ /*
+ * There is a group stop in progress. We don't need to
+ * start another one.
+ */
+ signr = sig->group_exit_code;
+ stop_count = --sig->group_stop_count;
+ current->exit_code = signr;
+ set_current_state(TASK_STOPPED);
+ if (stop_count == 0)
+ sig->flags = SIGNAL_STOP_STOPPED;
+ spin_unlock_irq(&sighand->siglock);
+ }
+ else if (thread_group_empty(current)) {
+ /*
+ * Lock must be held through transition to stopped state.
+ */
+ current->exit_code = current->signal->group_exit_code = signr;
+ set_current_state(TASK_STOPPED);
+ sig->flags = SIGNAL_STOP_STOPPED;
+ spin_unlock_irq(&sighand->siglock);
+ }
+ else {
+ /*
+ * There is no group stop already in progress.
+ * We must initiate one now, but that requires
+ * dropping siglock to get both the tasklist lock
+ * and siglock again in the proper order. Note that
+ * this allows an intervening SIGCONT to be posted.
+ * We need to check for that and bail out if necessary.
+ */
+ struct task_struct *t;
+
+ spin_unlock_irq(&sighand->siglock);
+
+ /* signals can be posted during this window */
+
+ read_lock(&tasklist_lock);
+ spin_lock_irq(&sighand->siglock);
+
+ if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED)) {
+ /*
+ * Another stop or continue happened while we
+ * didn't have the lock. We can just swallow this
+ * signal now. If we raced with a SIGCONT, that
+ * should have just cleared it now. If we raced
+ * with another processor delivering a stop signal,
+ * then the SIGCONT that wakes us up should clear it.
+ */
+ read_unlock(&tasklist_lock);
+ return 0;
+ }
+
+ if (sig->group_stop_count == 0) {
+ sig->group_exit_code = signr;
+ stop_count = 0;
+ for (t = next_thread(current); t != current;
+ t = next_thread(t))
+ /*
+ * Setting state to TASK_STOPPED for a group
+ * stop is always done with the siglock held,
+ * so this check has no races.
+ */
+ if (t->state < TASK_STOPPED) {
+ stop_count++;
+ signal_wake_up(t, 0);
+ }
+ sig->group_stop_count = stop_count;
+ }
+ else {
+ /* A race with another thread while unlocked. */
+ signr = sig->group_exit_code;
+ stop_count = --sig->group_stop_count;
+ }
+
+ current->exit_code = signr;
+ set_current_state(TASK_STOPPED);
+ if (stop_count == 0)
+ sig->flags = SIGNAL_STOP_STOPPED;
+
+ spin_unlock_irq(&sighand->siglock);
+ read_unlock(&tasklist_lock);
+ }
+
+ finish_stop(stop_count);
+ return 1;
+}
+
+/*
+ * Do appropriate magic when group_stop_count > 0.
+ * We return nonzero if we stopped, after releasing the siglock.
+ * We return zero if we still hold the siglock and should look
+ * for another signal without checking group_stop_count again.
+ */
+static inline int handle_group_stop(void)
+{
+ int stop_count;
+
+ if (current->signal->group_exit_task == current) {
+ /*
+ * Group stop is so we can do a core dump,
+ * We are the initiating thread, so get on with it.
+ */
+ current->signal->group_exit_task = NULL;
+ return 0;
+ }
+
+ if (current->signal->flags & SIGNAL_GROUP_EXIT)
+ /*
+ * Group stop is so another thread can do a core dump,
+ * or else we are racing against a death signal.
+ * Just punt the stop so we can get the next signal.
+ */
+ return 0;
+
+ /*
+ * There is a group stop in progress. We stop
+ * without any associated signal being in our queue.
+ */
+ stop_count = --current->signal->group_stop_count;
+ if (stop_count == 0)
+ current->signal->flags = SIGNAL_STOP_STOPPED;
+ current->exit_code = current->signal->group_exit_code;
+ set_current_state(TASK_STOPPED);
+ spin_unlock_irq(&current->sighand->siglock);
+ finish_stop(stop_count);
+ return 1;
+}
+
+int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
+ struct pt_regs *regs, void *cookie)
+{
+ sigset_t *mask = &current->blocked;
+ int signr = 0;
+
+relock:
+ spin_lock_irq(&current->sighand->siglock);
+ for (;;) {
+ struct k_sigaction *ka;
+
+ if (unlikely(current->signal->group_stop_count > 0) &&
+ handle_group_stop())
+ goto relock;
+
+ signr = dequeue_signal(current, mask, info);
+
+ if (!signr)
+ break; /* will return 0 */
+
+ if ((current->ptrace & PT_PTRACED) && signr != SIGKILL) {
+ ptrace_signal_deliver(regs, cookie);
+
+ /* Let the debugger run. */
+ ptrace_stop(signr, signr, info);
+
+ /* We're back. Did the debugger cancel the sig? */
+ signr = current->exit_code;
+ if (signr == 0)
+ continue;
+
+ current->exit_code = 0;
+
+ /* Update the siginfo structure if the signal has
+ changed. If the debugger wanted something
+ specific in the siginfo structure then it should
+ have updated *info via PTRACE_SETSIGINFO. */
+ if (signr != info->si_signo) {
+ info->si_signo = signr;
+ info->si_errno = 0;
+ info->si_code = SI_USER;
+ info->si_pid = current->parent->pid;
+ info->si_uid = current->parent->uid;
+ }
+
+ /* If the (new) signal is now blocked, requeue it. */
+ if (sigismember(&current->blocked, signr)) {
+ specific_send_sig_info(signr, info, current);
+ continue;
+ }
+ }
+
+ ka = &current->sighand->action[signr-1];
+ if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
+ continue;
+ if (ka->sa.sa_handler != SIG_DFL) {
+ /* Run the handler. */
+ *return_ka = *ka;
+
+ if (ka->sa.sa_flags & SA_ONESHOT)
+ ka->sa.sa_handler = SIG_DFL;
+
+ break; /* will return non-zero "signr" value */
+ }
+
+ /*
+ * Now we are doing the default action for this signal.
+ */
+ if (sig_kernel_ignore(signr)) /* Default is nothing. */
+ continue;
+
+ /* Init gets no signals it doesn't want. */
+ if (current->pid == 1)
+ continue;
+
+ if (sig_kernel_stop(signr)) {
+ /*
+ * The default action is to stop all threads in
+ * the thread group. The job control signals
+ * do nothing in an orphaned pgrp, but SIGSTOP
+ * always works. Note that siglock needs to be
+ * dropped during the call to is_orphaned_pgrp()
+ * because of lock ordering with tasklist_lock.
+ * This allows an intervening SIGCONT to be posted.
+ * We need to check for that and bail out if necessary.
+ */
+ if (signr != SIGSTOP) {
+ spin_unlock_irq(&current->sighand->siglock);
+
+ /* signals can be posted during this window */
+
+ if (is_orphaned_pgrp(process_group(current)))
+ goto relock;
+
+ spin_lock_irq(&current->sighand->siglock);
+ }
+
+ if (likely(do_signal_stop(signr))) {
+ /* It released the siglock. */
+ goto relock;
+ }
+
+ /*
+ * We didn't actually stop, due to a race
+ * with SIGCONT or something like that.
+ */
+ continue;
+ }
+
+ spin_unlock_irq(&current->sighand->siglock);
+
+ /*
+ * Anything else is fatal, maybe with a core dump.
+ */
+ current->flags |= PF_SIGNALED;
+ if (sig_kernel_coredump(signr)) {
+ /*
+ * If it was able to dump core, this kills all
+ * other threads in the group and synchronizes with
+ * their demise. If we lost the race with another
+ * thread getting here, it set group_exit_code
+ * first and our do_group_exit call below will use
+ * that value and ignore the one we pass it.
+ */
+ do_coredump((long)signr, signr, regs);
+ }
+
+ /*
+ * Death signals, no core dump.
+ */
+ do_group_exit(signr);
+ /* NOTREACHED */
+ }
+ spin_unlock_irq(&current->sighand->siglock);
+ return signr;
+}
+
+#endif
+
+EXPORT_SYMBOL(recalc_sigpending);
+EXPORT_SYMBOL_GPL(dequeue_signal);
+EXPORT_SYMBOL(flush_signals);
+EXPORT_SYMBOL(force_sig);
+EXPORT_SYMBOL(kill_pg);
+EXPORT_SYMBOL(kill_proc);
+EXPORT_SYMBOL(ptrace_notify);
+EXPORT_SYMBOL(send_sig);
+EXPORT_SYMBOL(send_sig_info);
+EXPORT_SYMBOL(sigprocmask);
+EXPORT_SYMBOL(block_all_signals);
+EXPORT_SYMBOL(unblock_all_signals);
+
+
+/*
+ * System call entry points.
+ */
+
+asmlinkage long sys_restart_syscall(void)
+{
+ struct restart_block *restart = &current_thread_info()->restart_block;
+ return restart->fn(restart);
+}
+
+long do_no_restart_syscall(struct restart_block *param)
+{
+ return -EINTR;
+}
+
+/*
+ * We don't need to get the kernel lock - this is all local to this
+ * particular thread.. (and that's good, because this is _heavily_
+ * used by various programs)
+ */
+
+/*
+ * This is also useful for kernel threads that want to temporarily
+ * (or permanently) block certain signals.
+ *
+ * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
+ * interface happily blocks "unblockable" signals like SIGKILL
+ * and friends.
+ */
+int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
+{
+ int error;
+ sigset_t old_block;
+
+ spin_lock_irq(&current->sighand->siglock);
+ old_block = current->blocked;
+ error = 0;
+ switch (how) {
+ case SIG_BLOCK:
+ sigorsets(&current->blocked, &current->blocked, set);
+ break;
+ case SIG_UNBLOCK:
+ signandsets(&current->blocked, &current->blocked, set);
+ break;
+ case SIG_SETMASK:
+ current->blocked = *set;
+ break;
+ default:
+ error = -EINVAL;
+ }
+ recalc_sigpending();
+ spin_unlock_irq(&current->sighand->siglock);
+ if (oldset)
+ *oldset = old_block;
+ return error;
+}
+
+asmlinkage long
+sys_rt_sigprocmask(int how, sigset_t __user *set, sigset_t __user *oset, size_t sigsetsize)
+{
+ int error = -EINVAL;
+ sigset_t old_set, new_set;
+
+ /* XXX: Don't preclude handling different sized sigset_t's. */
+ if (sigsetsize != sizeof(sigset_t))
+ goto out;
+
+ if (set) {
+ error = -EFAULT;
+ if (copy_from_user(&new_set, set, sizeof(*set)))
+ goto out;
+ sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
+
+ error = sigprocmask(how, &new_set, &old_set);
+ if (error)
+ goto out;
+ if (oset)
+ goto set_old;
+ } else if (oset) {
+ spin_lock_irq(&current->sighand->siglock);
+ old_set = current->blocked;
+ spin_unlock_irq(&current->sighand->siglock);
+
+ set_old:
+ error = -EFAULT;
+ if (copy_to_user(oset, &old_set, sizeof(*oset)))
+ goto out;
+ }
+ error = 0;
+out:
+ return error;
+}
+
+long do_sigpending(void __user *set, unsigned long sigsetsize)
+{
+ long error = -EINVAL;
+ sigset_t pending;
+
+ if (sigsetsize > sizeof(sigset_t))
+ goto out;
+
+ spin_lock_irq(&current->sighand->siglock);
+ sigorsets(&pending, &current->pending.signal,
+ &current->signal->shared_pending.signal);
+ spin_unlock_irq(&current->sighand->siglock);
+
+ /* Outside the lock because only this thread touches it. */
+ sigandsets(&pending, &current->blocked, &pending);
+
+ error = -EFAULT;
+ if (!copy_to_user(set, &pending, sigsetsize))
+ error = 0;
+
+out:
+ return error;
+}
+
+asmlinkage long
+sys_rt_sigpending(sigset_t __user *set, size_t sigsetsize)
+{
+ return do_sigpending(set, sigsetsize);
+}
+
+#ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
+
+int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
+{
+ int err;
+
+ if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
+ return -EFAULT;
+ if (from->si_code < 0)
+ return __copy_to_user(to, from, sizeof(siginfo_t))
+ ? -EFAULT : 0;
+ /*
+ * If you change siginfo_t structure, please be sure
+ * this code is fixed accordingly.
+ * It should never copy any pad contained in the structure
+ * to avoid security leaks, but must copy the generic
+ * 3 ints plus the relevant union member.
+ */
+ err = __put_user(from->si_signo, &to->si_signo);
+ err |= __put_user(from->si_errno, &to->si_errno);
+ err |= __put_user((short)from->si_code, &to->si_code);
+ switch (from->si_code & __SI_MASK) {
+ case __SI_KILL:
+ err |= __put_user(from->si_pid, &to->si_pid);
+ err |= __put_user(from->si_uid, &to->si_uid);
+ break;
+ case __SI_TIMER:
+ err |= __put_user(from->si_tid, &to->si_tid);
+ err |= __put_user(from->si_overrun, &to->si_overrun);
+ err |= __put_user(from->si_ptr, &to->si_ptr);
+ break;
+ case __SI_POLL:
+ err |= __put_user(from->si_band, &to->si_band);
+ err |= __put_user(from->si_fd, &to->si_fd);
+ break;
+ case __SI_FAULT:
+ err |= __put_user(from->si_addr, &to->si_addr);
+#ifdef __ARCH_SI_TRAPNO
+ err |= __put_user(from->si_trapno, &to->si_trapno);
+#endif
+ break;
+ case __SI_CHLD:
+ err |= __put_user(from->si_pid, &to->si_pid);
+ err |= __put_user(from->si_uid, &to->si_uid);
+ err |= __put_user(from->si_status, &to->si_status);
+ err |= __put_user(from->si_utime, &to->si_utime);
+ err |= __put_user(from->si_stime, &to->si_stime);
+ break;
+ case __SI_RT: /* This is not generated by the kernel as of now. */
+ case __SI_MESGQ: /* But this is */
+ err |= __put_user(from->si_pid, &to->si_pid);
+ err |= __put_user(from->si_uid, &to->si_uid);
+ err |= __put_user(from->si_ptr, &to->si_ptr);
+ break;
+ default: /* this is just in case for now ... */
+ err |= __put_user(from->si_pid, &to->si_pid);
+ err |= __put_user(from->si_uid, &to->si_uid);
+ break;
+ }
+ return err;
+}
+
+#endif
+
+asmlinkage long
+sys_rt_sigtimedwait(const sigset_t __user *uthese,
+ siginfo_t __user *uinfo,
+ const struct timespec __user *uts,
+ size_t sigsetsize)
+{
+ int ret, sig;
+ sigset_t these;
+ struct timespec ts;
+ siginfo_t info;
+ long timeout = 0;
+
+ /* XXX: Don't preclude handling different sized sigset_t's. */
+ if (sigsetsize != sizeof(sigset_t))
+ return -EINVAL;
+
+ if (copy_from_user(&these, uthese, sizeof(these)))
+ return -EFAULT;
+
+ /*
+ * Invert the set of allowed signals to get those we
+ * want to block.
+ */
+ sigdelsetmask(&these, sigmask(SIGKILL)|sigmask(SIGSTOP));
+ signotset(&these);
+
+ if (uts) {
+ if (copy_from_user(&ts, uts, sizeof(ts)))
+ return -EFAULT;
+ if (ts.tv_nsec >= 1000000000L || ts.tv_nsec < 0
+ || ts.tv_sec < 0)
+ return -EINVAL;
+ }
+
+ spin_lock_irq(&current->sighand->siglock);
+ sig = dequeue_signal(current, &these, &info);
+ if (!sig) {
+ timeout = MAX_SCHEDULE_TIMEOUT;
+ if (uts)
+ timeout = (timespec_to_jiffies(&ts)
+ + (ts.tv_sec || ts.tv_nsec));
+
+ if (timeout) {
+ /* None ready -- temporarily unblock those we're
+ * interested while we are sleeping in so that we'll
+ * be awakened when they arrive. */
+ current->real_blocked = current->blocked;
+ sigandsets(&current->blocked, &current->blocked, &these);
+ recalc_sigpending();
+ spin_unlock_irq(&current->sighand->siglock);
+
+ current->state = TASK_INTERRUPTIBLE;
+ timeout = schedule_timeout(timeout);
+
+ if (current->flags & PF_FREEZE)
+ refrigerator(PF_FREEZE);
+ spin_lock_irq(&current->sighand->siglock);
+ sig = dequeue_signal(current, &these, &info);
+ current->blocked = current->real_blocked;
+ siginitset(&current->real_blocked, 0);
+ recalc_sigpending();
+ }
+ }
+ spin_unlock_irq(&current->sighand->siglock);
+
+ if (sig) {
+ ret = sig;
+ if (uinfo) {
+ if (copy_siginfo_to_user(uinfo, &info))
+ ret = -EFAULT;
+ }
+ } else {
+ ret = -EAGAIN;
+ if (timeout)
+ ret = -EINTR;
+ }
+
+ return ret;
+}
+
+asmlinkage long
+sys_kill(int pid, int sig)
+{
+ struct siginfo info;
+
+ info.si_signo = sig;
+ info.si_errno = 0;
+ info.si_code = SI_USER;
+ info.si_pid = current->tgid;
+ info.si_uid = current->uid;
+
+ return kill_something_info(sig, &info, pid);
+}
+
+/**
+ * sys_tgkill - send signal to one specific thread
+ * @tgid: the thread group ID of the thread
+ * @pid: the PID of the thread
+ * @sig: signal to be sent
+ *
+ * This syscall also checks the tgid and returns -ESRCH even if the PID
+ * exists but it's not belonging to the target process anymore. This
+ * method solves the problem of threads exiting and PIDs getting reused.
+ */
+asmlinkage long sys_tgkill(int tgid, int pid, int sig)
+{
+ struct siginfo info;
+ int error;
+ struct task_struct *p;
+
+ /* This is only valid for single tasks */
+ if (pid <= 0 || tgid <= 0)
+ return -EINVAL;
+
+ info.si_signo = sig;
+ info.si_errno = 0;
+ info.si_code = SI_TKILL;
+ info.si_pid = current->tgid;
+ info.si_uid = current->uid;
+
+ read_lock(&tasklist_lock);
+ p = find_task_by_pid(pid);
+ error = -ESRCH;
+ if (p && (p->tgid == tgid)) {
+ error = check_kill_permission(sig, &info, p);
+ /*
+ * The null signal is a permissions and process existence
+ * probe. No signal is actually delivered.
+ */
+ if (!error && sig && p->sighand) {
+ spin_lock_irq(&p->sighand->siglock);
+ handle_stop_signal(sig, p);
+ error = specific_send_sig_info(sig, &info, p);
+ spin_unlock_irq(&p->sighand->siglock);
+ }
+ }
+ read_unlock(&tasklist_lock);
+ return error;
+}
+
+/*
+ * Send a signal to only one task, even if it's a CLONE_THREAD task.
+ */
+asmlinkage long
+sys_tkill(int pid, int sig)
+{
+ struct siginfo info;
+ int error;
+ struct task_struct *p;
+
+ /* This is only valid for single tasks */
+ if (pid <= 0)
+ return -EINVAL;
+
+ info.si_signo = sig;
+ info.si_errno = 0;
+ info.si_code = SI_TKILL;
+ info.si_pid = current->tgid;
+ info.si_uid = current->uid;
+
+ read_lock(&tasklist_lock);
+ p = find_task_by_pid(pid);
+ error = -ESRCH;
+ if (p) {
+ error = check_kill_permission(sig, &info, p);
+ /*
+ * The null signal is a permissions and process existence
+ * probe. No signal is actually delivered.
+ */
+ if (!error && sig && p->sighand) {
+ spin_lock_irq(&p->sighand->siglock);
+ handle_stop_signal(sig, p);
+ error = specific_send_sig_info(sig, &info, p);
+ spin_unlock_irq(&p->sighand->siglock);
+ }
+ }
+ read_unlock(&tasklist_lock);
+ return error;
+}
+
+asmlinkage long
+sys_rt_sigqueueinfo(int pid, int sig, siginfo_t __user *uinfo)
+{
+ siginfo_t info;
+
+ if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
+ return -EFAULT;
+
+ /* Not even root can pretend to send signals from the kernel.
+ Nor can they impersonate a kill(), which adds source info. */
+ if (info.si_code >= 0)
+ return -EPERM;
+ info.si_signo = sig;
+
+ /* POSIX.1b doesn't mention process groups. */
+ return kill_proc_info(sig, &info, pid);
+}
+
+int
+do_sigaction(int sig, const struct k_sigaction *act, struct k_sigaction *oact)
+{
+ struct k_sigaction *k;
+
+ if (sig < 1 || sig > _NSIG || (act && sig_kernel_only(sig)))
+ return -EINVAL;
+
+ k = &current->sighand->action[sig-1];
+
+ spin_lock_irq(&current->sighand->siglock);
+ if (signal_pending(current)) {
+ /*
+ * If there might be a fatal signal pending on multiple
+ * threads, make sure we take it before changing the action.
+ */
+ spin_unlock_irq(&current->sighand->siglock);
+ return -ERESTARTNOINTR;
+ }
+
+ if (oact)
+ *oact = *k;
+
+ if (act) {
+ /*
+ * POSIX 3.3.1.3:
+ * "Setting a signal action to SIG_IGN for a signal that is
+ * pending shall cause the pending signal to be discarded,
+ * whether or not it is blocked."
+ *
+ * "Setting a signal action to SIG_DFL for a signal that is
+ * pending and whose default action is to ignore the signal
+ * (for example, SIGCHLD), shall cause the pending signal to
+ * be discarded, whether or not it is blocked"
+ */
+ if (act->sa.sa_handler == SIG_IGN ||
+ (act->sa.sa_handler == SIG_DFL &&
+ sig_kernel_ignore(sig))) {
+ /*
+ * This is a fairly rare case, so we only take the
+ * tasklist_lock once we're sure we'll need it.
+ * Now we must do this little unlock and relock
+ * dance to maintain the lock hierarchy.
+ */
+ struct task_struct *t = current;
+ spin_unlock_irq(&t->sighand->siglock);
+ read_lock(&tasklist_lock);
+ spin_lock_irq(&t->sighand->siglock);
+ *k = *act;
+ sigdelsetmask(&k->sa.sa_mask,
+ sigmask(SIGKILL) | sigmask(SIGSTOP));
+ rm_from_queue(sigmask(sig), &t->signal->shared_pending);
+ do {
+ rm_from_queue(sigmask(sig), &t->pending);
+ recalc_sigpending_tsk(t);
+ t = next_thread(t);
+ } while (t != current);
+ spin_unlock_irq(&current->sighand->siglock);
+ read_unlock(&tasklist_lock);
+ return 0;
+ }
+
+ *k = *act;
+ sigdelsetmask(&k->sa.sa_mask,
+ sigmask(SIGKILL) | sigmask(SIGSTOP));
+ }
+
+ spin_unlock_irq(&current->sighand->siglock);
+ return 0;
+}
+
+int
+do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
+{
+ stack_t oss;
+ int error;
+
+ if (uoss) {
+ oss.ss_sp = (void __user *) current->sas_ss_sp;
+ oss.ss_size = current->sas_ss_size;
+ oss.ss_flags = sas_ss_flags(sp);
+ }
+
+ if (uss) {
+ void __user *ss_sp;
+ size_t ss_size;
+ int ss_flags;
+
+ error = -EFAULT;
+ if (!access_ok(VERIFY_READ, uss, sizeof(*uss))
+ || __get_user(ss_sp, &uss->ss_sp)
+ || __get_user(ss_flags, &uss->ss_flags)
+ || __get_user(ss_size, &uss->ss_size))
+ goto out;
+
+ error = -EPERM;
+ if (on_sig_stack(sp))
+ goto out;
+
+ error = -EINVAL;
+ /*
+ *
+ * Note - this code used to test ss_flags incorrectly
+ * old code may have been written using ss_flags==0
+ * to mean ss_flags==SS_ONSTACK (as this was the only
+ * way that worked) - this fix preserves that older
+ * mechanism
+ */
+ if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
+ goto out;
+
+ if (ss_flags == SS_DISABLE) {
+ ss_size = 0;
+ ss_sp = NULL;
+ } else {
+ error = -ENOMEM;
+ if (ss_size < MINSIGSTKSZ)
+ goto out;
+ }
+
+ current->sas_ss_sp = (unsigned long) ss_sp;
+ current->sas_ss_size = ss_size;
+ }
+
+ if (uoss) {
+ error = -EFAULT;
+ if (copy_to_user(uoss, &oss, sizeof(oss)))
+ goto out;
+ }
+
+ error = 0;
+out:
+ return error;
+}
+
+#ifdef __ARCH_WANT_SYS_SIGPENDING
+
+asmlinkage long
+sys_sigpending(old_sigset_t __user *set)
+{
+ return do_sigpending(set, sizeof(*set));
+}
+
+#endif
+
+#ifdef __ARCH_WANT_SYS_SIGPROCMASK
+/* Some platforms have their own version with special arguments others
+ support only sys_rt_sigprocmask. */
+
+asmlinkage long
+sys_sigprocmask(int how, old_sigset_t __user *set, old_sigset_t __user *oset)
+{
+ int error;
+ old_sigset_t old_set, new_set;
+
+ if (set) {
+ error = -EFAULT;
+ if (copy_from_user(&new_set, set, sizeof(*set)))
+ goto out;
+ new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
+
+ spin_lock_irq(&current->sighand->siglock);
+ old_set = current->blocked.sig[0];
+
+ error = 0;
+ switch (how) {
+ default:
+ error = -EINVAL;
+ break;
+ case SIG_BLOCK:
+ sigaddsetmask(&current->blocked, new_set);
+ break;
+ case SIG_UNBLOCK:
+ sigdelsetmask(&current->blocked, new_set);
+ break;
+ case SIG_SETMASK:
+ current->blocked.sig[0] = new_set;
+ break;
+ }
+
+ recalc_sigpending();
+ spin_unlock_irq(&current->sighand->siglock);
+ if (error)
+ goto out;
+ if (oset)
+ goto set_old;
+ } else if (oset) {
+ old_set = current->blocked.sig[0];
+ set_old:
+ error = -EFAULT;
+ if (copy_to_user(oset, &old_set, sizeof(*oset)))
+ goto out;
+ }
+ error = 0;
+out:
+ return error;
+}
+#endif /* __ARCH_WANT_SYS_SIGPROCMASK */
+
+#ifdef __ARCH_WANT_SYS_RT_SIGACTION
+asmlinkage long
+sys_rt_sigaction(int sig,
+ const struct sigaction __user *act,
+ struct sigaction __user *oact,
+ size_t sigsetsize)
+{
+ struct k_sigaction new_sa, old_sa;
+ int ret = -EINVAL;
+
+ /* XXX: Don't preclude handling different sized sigset_t's. */
+ if (sigsetsize != sizeof(sigset_t))
+ goto out;
+
+ if (act) {
+ if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
+ return -EFAULT;
+ }
+
+ ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
+
+ if (!ret && oact) {
+ if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
+ return -EFAULT;
+ }
+out:
+ return ret;
+}
+#endif /* __ARCH_WANT_SYS_RT_SIGACTION */
+
+#ifdef __ARCH_WANT_SYS_SGETMASK
+
+/*
+ * For backwards compatibility. Functionality superseded by sigprocmask.
+ */
+asmlinkage long
+sys_sgetmask(void)
+{
+ /* SMP safe */
+ return current->blocked.sig[0];
+}
+
+asmlinkage long
+sys_ssetmask(int newmask)
+{
+ int old;
+
+ spin_lock_irq(&current->sighand->siglock);
+ old = current->blocked.sig[0];
+
+ siginitset(&current->blocked, newmask & ~(sigmask(SIGKILL)|
+ sigmask(SIGSTOP)));
+ recalc_sigpending();
+ spin_unlock_irq(&current->sighand->siglock);
+
+ return old;
+}
+#endif /* __ARCH_WANT_SGETMASK */
+
+#ifdef __ARCH_WANT_SYS_SIGNAL
+/*
+ * For backwards compatibility. Functionality superseded by sigaction.
+ */
+asmlinkage unsigned long
+sys_signal(int sig, __sighandler_t handler)
+{
+ struct k_sigaction new_sa, old_sa;
+ int ret;
+
+ new_sa.sa.sa_handler = handler;
+ new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
+
+ ret = do_sigaction(sig, &new_sa, &old_sa);
+
+ return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
+}
+#endif /* __ARCH_WANT_SYS_SIGNAL */
+
+#ifdef __ARCH_WANT_SYS_PAUSE
+
+asmlinkage long
+sys_pause(void)
+{
+ current->state = TASK_INTERRUPTIBLE;
+ schedule();
+ return -ERESTARTNOHAND;
+}
+
+#endif
+
+void __init signals_init(void)
+{
+ sigqueue_cachep =
+ kmem_cache_create("sigqueue",
+ sizeof(struct sigqueue),
+ __alignof__(struct sigqueue),
+ SLAB_PANIC, NULL, NULL);
+}