X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=kernel%2Fsignal.c;h=e661b01d340f06a17afb6cfef13a712ae0338ff9;hb=8dddfe192632361b62eee9c8320bc9feff57898b;hp=64ad0ed15992562a4b67da61e4b34746dc9c48c7;hpb=f5264481c8049673e2cc8c7aca410931f571ba2d;p=safe%2Fjmp%2Flinux-2.6 diff --git a/kernel/signal.c b/kernel/signal.c index 64ad0ed..e661b01 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -22,6 +22,7 @@ #include #include #include +#include #include #include #include @@ -39,16 +40,21 @@ static struct kmem_cache *sigqueue_cachep; +static void __user *sig_handler(struct task_struct *t, int sig) +{ + return t->sighand->action[sig - 1].sa.sa_handler; +} -static int sig_ignored(struct task_struct *t, int sig) +static int sig_handler_ignored(void __user *handler, int sig) { - void __user * handler; + /* Is it explicitly or implicitly ignored? */ + return handler == SIG_IGN || + (handler == SIG_DFL && sig_kernel_ignore(sig)); +} - /* - * Tracers always want to know about signals.. - */ - if (t->ptrace & PT_PTRACED) - return 0; +static int sig_ignored(struct task_struct *t, int sig) +{ + void __user *handler; /* * Blocked signals are never ignored, since the @@ -58,10 +64,14 @@ static int sig_ignored(struct task_struct *t, int sig) if (sigismember(&t->blocked, sig) || sigismember(&t->real_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)); + handler = sig_handler(t, sig); + if (!sig_handler_ignored(handler, sig)) + return 0; + + /* + * Tracers may want to know about even ignored signals. + */ + return !tracehook_consider_ignored_signal(t, sig, handler); } /* @@ -124,7 +134,9 @@ void recalc_sigpending_and_wake(struct task_struct *t) void recalc_sigpending(void) { - if (!recalc_sigpending_tsk(current) && !freezing(current)) + if (unlikely(tracehook_force_sigpending())) + set_thread_flag(TIF_SIGPENDING); + else if (!recalc_sigpending_tsk(current) && !freezing(current)) clear_thread_flag(TIF_SIGPENDING); } @@ -226,6 +238,40 @@ void flush_signals(struct task_struct *t) spin_unlock_irqrestore(&t->sighand->siglock, flags); } +static void __flush_itimer_signals(struct sigpending *pending) +{ + sigset_t signal, retain; + struct sigqueue *q, *n; + + signal = pending->signal; + sigemptyset(&retain); + + list_for_each_entry_safe(q, n, &pending->list, list) { + int sig = q->info.si_signo; + + if (likely(q->info.si_code != SI_TIMER)) { + sigaddset(&retain, sig); + } else { + sigdelset(&signal, sig); + list_del_init(&q->list); + __sigqueue_free(q); + } + } + + sigorsets(&pending->signal, &signal, &retain); +} + +void flush_itimer_signals(void) +{ + struct task_struct *tsk = current; + unsigned long flags; + + spin_lock_irqsave(&tsk->sighand->siglock, flags); + __flush_itimer_signals(&tsk->pending); + __flush_itimer_signals(&tsk->signal->shared_pending); + spin_unlock_irqrestore(&tsk->sighand->siglock, flags); +} + void ignore_signals(struct task_struct *t) { int i; @@ -256,12 +302,12 @@ flush_signal_handlers(struct task_struct *t, int force_default) int unhandled_signal(struct task_struct *tsk, int sig) { + void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler; if (is_global_init(tsk)) return 1; - if (tsk->ptrace & PT_PTRACED) + if (handler != SIG_IGN && handler != SIG_DFL) return 0; - return (tsk->sighand->action[sig-1].sa.sa_handler == SIG_IGN) || - (tsk->sighand->action[sig-1].sa.sa_handler == SIG_DFL); + return !tracehook_consider_fatal_signal(tsk, sig, handler); } @@ -299,13 +345,9 @@ unblock_all_signals(void) spin_unlock_irqrestore(¤t->sighand->siglock, flags); } -static int collect_signal(int sig, struct sigpending *list, siginfo_t *info) +static void 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 @@ -313,33 +355,30 @@ static int collect_signal(int sig, struct sigpending *list, siginfo_t *info) */ list_for_each_entry(q, &list->list, list) { if (q->info.si_signo == sig) { - if (first) { - still_pending = 1; - break; - } + if (first) + goto still_pending; first = q; } } + + sigdelset(&list->signal, sig); + if (first) { +still_pending: 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, @@ -357,8 +396,7 @@ static int __dequeue_signal(struct sigpending *pending, sigset_t *mask, } } - if (!collect_signal(sig, pending, info)) - sig = 0; + collect_signal(sig, pending, info); } return sig; @@ -372,7 +410,7 @@ static int __dequeue_signal(struct sigpending *pending, sigset_t *mask, */ int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info) { - int signr = 0; + int signr; /* We only dequeue private signals from ourselves, we don't let * signalfd steal them @@ -405,8 +443,12 @@ int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info) } } } + recalc_sigpending(); - if (signr && unlikely(sig_kernel_stop(signr))) { + if (!signr) + return 0; + + if (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 @@ -419,12 +461,9 @@ int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info) * is to alert stop-signal processing code when another * processor has come along and cleared the flag. */ - if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT)) - tsk->signal->flags |= SIGNAL_STOP_DEQUEUED; + tsk->signal->flags |= SIGNAL_STOP_DEQUEUED; } - if (signr && - ((info->si_code & __SI_MASK) == __SI_TIMER) && - info->si_sys_private) { + if ((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 @@ -526,86 +565,78 @@ static int rm_from_queue(unsigned long mask, struct sigpending *s) static int check_kill_permission(int sig, struct siginfo *info, struct task_struct *t) { - int error = -EINVAL; + struct pid *sid; + int error; + if (!valid_signal(sig)) - return error; + return -EINVAL; - if (info == SEND_SIG_NOINFO || (!is_si_special(info) && SI_FROMUSER(info))) { - error = audit_signal_info(sig, t); /* Let audit system see the signal */ - if (error) - return error; - error = -EPERM; - if (((sig != SIGCONT) || - (task_session_nr(current) != task_session_nr(t))) - && (current->euid ^ t->suid) && (current->euid ^ t->uid) - && (current->uid ^ t->suid) && (current->uid ^ t->uid) - && !capable(CAP_KILL)) + if (info != SEND_SIG_NOINFO && (is_si_special(info) || SI_FROMKERNEL(info))) + return 0; + + error = audit_signal_info(sig, t); /* Let audit system see the signal */ + if (error) return error; + + if ((current->euid ^ t->suid) && (current->euid ^ t->uid) && + (current->uid ^ t->suid) && (current->uid ^ t->uid) && + !capable(CAP_KILL)) { + switch (sig) { + case SIGCONT: + sid = task_session(t); + /* + * We don't return the error if sid == NULL. The + * task was unhashed, the caller must notice this. + */ + if (!sid || sid == task_session(current)) + break; + default: + return -EPERM; + } } return security_task_kill(t, info, sig, 0); } -/* forward decl */ -static void do_notify_parent_cldstop(struct task_struct *tsk, int why); - /* - * Handle magic process-wide effects of stop/continue signals. - * Unlike the signal actions, these happen immediately at signal-generation + * 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. + * signals. The process stop is done as a signal action for SIG_DFL. + * + * Returns true if the signal should be actually delivered, otherwise + * it should be dropped. */ -static void handle_stop_signal(int sig, struct task_struct *p) +static int prepare_signal(int sig, struct task_struct *p) { + struct signal_struct *signal = p->signal; struct task_struct *t; - if (p->signal->flags & SIGNAL_GROUP_EXIT) + if (unlikely(signal->flags & SIGNAL_GROUP_EXIT)) { /* - * The process is in the middle of dying already. + * The process is in the middle of dying, nothing to do. */ - return; - - if (sig_kernel_stop(sig)) { + } else if (sig_kernel_stop(sig)) { /* * This is a stop signal. Remove SIGCONT from all queues. */ - rm_from_queue(sigmask(SIGCONT), &p->signal->shared_pending); + rm_from_queue(sigmask(SIGCONT), &signal->shared_pending); t = p; do { rm_from_queue(sigmask(SIGCONT), &t->pending); - t = next_thread(t); - } while (t != p); + } while_each_thread(p, t); } else if (sig == SIGCONT) { + unsigned int why; /* * 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); - do_notify_parent_cldstop(p, CLD_STOPPED); - spin_lock(&p->sighand->siglock); - } - rm_from_queue(SIG_KERNEL_STOP_MASK, &p->signal->shared_pending); + rm_from_queue(SIG_KERNEL_STOP_MASK, &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 @@ -615,7 +646,7 @@ static void handle_stop_signal(int sig, struct task_struct *p) * 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. + * the pending signal. * * Wake up the stopped thread _after_ setting * TIF_SIGPENDING @@ -626,49 +657,164 @@ static void handle_stop_signal(int sig, struct task_struct *p) state |= TASK_INTERRUPTIBLE; } wake_up_state(t, state); + } while_each_thread(p, t); - t = next_thread(t); - } while (t != p); + /* + * Notify the parent with CLD_CONTINUED if we were stopped. + * + * If we were in the middle of a group stop, we pretend it + * was already finished, and then continued. Since SIGCHLD + * doesn't queue we report only CLD_STOPPED, as if the next + * CLD_CONTINUED was dropped. + */ + why = 0; + if (signal->flags & SIGNAL_STOP_STOPPED) + why |= SIGNAL_CLD_CONTINUED; + else if (signal->group_stop_count) + why |= SIGNAL_CLD_STOPPED; - if (p->signal->flags & SIGNAL_STOP_STOPPED) { + if (why) { /* - * We were in fact stopped, and are now continued. - * Notify the parent with CLD_CONTINUED. + * The first thread which returns from finish_stop() + * will take ->siglock, notice SIGNAL_CLD_MASK, and + * notify its parent. See get_signal_to_deliver(). */ - p->signal->flags = SIGNAL_STOP_CONTINUED; - p->signal->group_exit_code = 0; - spin_unlock(&p->sighand->siglock); - do_notify_parent_cldstop(p, CLD_CONTINUED); - spin_lock(&p->sighand->siglock); + signal->flags = why | SIGNAL_STOP_CONTINUED; + signal->group_stop_count = 0; + signal->group_exit_code = 0; } 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; + signal->flags &= ~SIGNAL_STOP_DEQUEUED; } - } else if (sig == SIGKILL) { + } + + return !sig_ignored(p, sig); +} + +/* + * 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. + */ +static inline int wants_signal(int sig, struct task_struct *p) +{ + if (sigismember(&p->blocked, sig)) + return 0; + if (p->flags & PF_EXITING) + return 0; + if (sig == SIGKILL) + return 1; + if (task_is_stopped_or_traced(p)) + return 0; + return task_curr(p) || !signal_pending(p); +} + +static void complete_signal(int sig, struct task_struct *p, int group) +{ + struct signal_struct *signal = p->signal; + struct task_struct *t; + + /* + * 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)) + t = p; + else if (!group || thread_group_empty(p)) /* - * Make sure that any pending stop signal already dequeued - * is undone by the wakeup for SIGKILL. + * There is just one thread and it does not need to be woken. + * It will dequeue unblocked signals before it runs again. */ - p->signal->flags = 0; + return; + else { + /* + * Otherwise try to find a suitable thread. + */ + t = signal->curr_target; + while (!wants_signal(sig, t)) { + t = next_thread(t); + if (t == signal->curr_target) + /* + * No thread needs to be woken. + * Any eligible threads will see + * the signal in the queue soon. + */ + return; + } + 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) && + !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) && + !sigismember(&t->real_blocked, sig) && + (sig == SIGKILL || + !tracehook_consider_fatal_signal(t, sig, SIG_DFL))) { + /* + * 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. + */ + signal->flags = SIGNAL_GROUP_EXIT; + signal->group_exit_code = sig; + signal->group_stop_count = 0; + t = p; + do { + sigaddset(&t->pending.signal, SIGKILL); + signal_wake_up(t, 1); + } while_each_thread(p, t); + 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; +} + +static inline int legacy_queue(struct sigpending *signals, int sig) +{ + return (sig < SIGRTMIN) && sigismember(&signals->signal, sig); } static int send_signal(int sig, struct siginfo *info, struct task_struct *t, - struct sigpending *signals) + int group) { - struct sigqueue * q = NULL; - int ret = 0; + struct sigpending *pending; + struct sigqueue *q; + assert_spin_locked(&t->sighand->siglock); + if (!prepare_signal(sig, t)) + return 0; + + pending = group ? &t->signal->shared_pending : &t->pending; /* - * Deliver the signal to listening signalfds. This must be called - * with the sighand lock held. + * Short-circuit ignored signals and support queuing + * exactly one non-rt signal, so that we can get more + * detailed information about the cause of the signal. */ - signalfd_notify(t, sig); - + if (legacy_queue(pending, sig)) + return 0; /* * fast-pathed signals for kernel-internal things like SIGSTOP * or SIGKILL. @@ -688,7 +834,7 @@ static int send_signal(int sig, struct siginfo *info, struct task_struct *t, (is_si_special(info) || info->si_code >= 0))); if (q) { - list_add_tail(&q->list, &signals->list); + list_add_tail(&q->list, &pending->list); switch ((unsigned long) info) { case (unsigned long) SEND_SIG_NOINFO: q->info.si_signo = sig; @@ -718,13 +864,12 @@ static int send_signal(int sig, struct siginfo *info, struct task_struct *t, } out_set: - sigaddset(&signals->signal, sig); - return ret; + signalfd_notify(t, sig); + sigaddset(&pending->signal, sig); + complete_signal(sig, t, group); + return 0; } -#define LEGACY_QUEUE(sigptr, sig) \ - (((sig) < SIGRTMIN) && sigismember(&(sigptr)->signal, (sig))) - int print_fatal_signals; static void print_fatal_signal(struct pt_regs *regs, int signr) @@ -757,29 +902,16 @@ static int __init setup_print_fatal_signals(char *str) __setup("print-fatal-signals=", setup_print_fatal_signals); +int +__group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p) +{ + return send_signal(sig, info, p, 1); +} + static int specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t) { - int ret = 0; - - BUG_ON(!irqs_disabled()); - assert_spin_locked(&t->sighand->siglock); - - /* 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; + return send_signal(sig, info, t, 0); } /* @@ -790,7 +922,8 @@ out: * since we do not want to have a signal handler that was blocked * be invoked when user space had explicitly blocked it. * - * We don't want to have recursive SIGSEGV's etc, for example. + * We don't want to have recursive SIGSEGV's etc, for example, + * that is why we also clear SIGNAL_UNKILLABLE. */ int force_sig_info(int sig, struct siginfo *info, struct task_struct *t) @@ -810,6 +943,8 @@ force_sig_info(int sig, struct siginfo *info, struct task_struct *t) recalc_sigpending_and_wake(t); } } + if (action->sa.sa_handler == SIG_DFL) + t->signal->flags &= ~SIGNAL_UNKILLABLE; ret = specific_send_sig_info(sig, info, t); spin_unlock_irqrestore(&t->sighand->siglock, flags); @@ -823,134 +958,6 @@ force_sig_specific(int sig, struct task_struct *t) } /* - * 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. - */ -static inline int wants_signal(int sig, struct task_struct *p) -{ - if (sigismember(&p->blocked, sig)) - return 0; - if (p->flags & PF_EXITING) - return 0; - if (sig == SIGKILL) - return 1; - if (task_is_stopped_or_traced(p)) - return 0; - return task_curr(p) || !signal_pending(p); -} - -static void -__group_complete_signal(int sig, struct task_struct *p) -{ - struct task_struct *t; - - /* - * 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)) - 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; - - while (!wants_signal(sig, t)) { - 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); - } while_each_thread(p, t); - 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); - - /* 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) @@ -978,13 +985,11 @@ int __fatal_signal_pending(struct task_struct *tsk) } EXPORT_SYMBOL(__fatal_signal_pending); -/* - * Must be called under rcu_read_lock() or with tasklist_lock read-held. - */ struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long *flags) { struct sighand_struct *sighand; + rcu_read_lock(); for (;;) { sighand = rcu_dereference(tsk->sighand); if (unlikely(sighand == NULL)) @@ -995,6 +1000,7 @@ struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long break; spin_unlock_irqrestore(&sighand->siglock, *flags); } + rcu_read_unlock(); return sighand; } @@ -1043,9 +1049,6 @@ int kill_pid_info(int sig, struct siginfo *info, struct pid *pid) struct task_struct *p; rcu_read_lock(); - if (unlikely(sig_needs_tasklist(sig))) - read_lock(&tasklist_lock); - retry: p = pid_task(pid, PIDTYPE_PID); if (p) { @@ -1059,10 +1062,8 @@ retry: */ goto retry; } - - if (unlikely(sig_needs_tasklist(sig))) - read_unlock(&tasklist_lock); rcu_read_unlock(); + return error; } @@ -1120,7 +1121,7 @@ EXPORT_SYMBOL_GPL(kill_pid_info_as_uid); * is probably wrong. Should make it like BSD or SYSV. */ -static int kill_something_info(int sig, struct siginfo *info, int pid) +static int kill_something_info(int sig, struct siginfo *info, pid_t pid) { int ret; @@ -1159,8 +1160,7 @@ static int kill_something_info(int sig, struct siginfo *info, int pid) */ /* - * These two are the most common entry points. They send a signal - * just to the specific thread. + * The caller must ensure the task can't exit. */ int send_sig_info(int sig, struct siginfo *info, struct task_struct *p) @@ -1175,17 +1175,9 @@ send_sig_info(int sig, struct siginfo *info, struct task_struct *p) if (!valid_signal(sig)) 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; } @@ -1241,17 +1233,6 @@ int kill_pid(struct pid *pid, int sig, int priv) } EXPORT_SYMBOL(kill_pid); -int -kill_proc(pid_t pid, int sig, int priv) -{ - int ret; - - rcu_read_lock(); - ret = kill_pid_info(sig, __si_special(priv), find_pid(pid)); - rcu_read_unlock(); - return ret; -} - /* * These functions support sending signals using preallocated sigqueue * structures. This is needed "because realtime applications cannot @@ -1278,121 +1259,61 @@ void sigqueue_free(struct sigqueue *q) BUG_ON(!(q->flags & SIGQUEUE_PREALLOC)); /* - * If the signal is still pending remove it from the - * pending queue. We must hold ->siglock while testing - * q->list to serialize with collect_signal(). + * We must hold ->siglock while testing q->list + * to serialize with collect_signal() or with + * __exit_signal()->flush_sigqueue(). */ spin_lock_irqsave(lock, flags); - if (!list_empty(&q->list)) - list_del_init(&q->list); - spin_unlock_irqrestore(lock, flags); - 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; - - BUG_ON(!(q->flags & SIGQUEUE_PREALLOC)); - /* - * The rcu based delayed sighand destroy makes it possible to - * run this without tasklist lock held. The task struct itself - * cannot go away as create_timer did get_task_struct(). - * - * We return -1, when the task is marked exiting, so - * posix_timer_event can redirect it to the group leader + * If it is queued it will be freed when dequeued, + * like the "regular" sigqueue. */ - rcu_read_lock(); - - if (!likely(lock_task_sighand(p, &flags))) { - ret = -1; - goto out_err; - } - - if (unlikely(!list_empty(&q->list))) { - /* - * If an SI_TIMER entry is already queue just increment - * the overrun count. - */ - BUG_ON(q->info.si_code != SI_TIMER); - q->info.si_overrun++; - goto out; - } - /* Short-circuit ignored signals. */ - if (sig_ignored(p, sig)) { - ret = 1; - goto out; - } - /* - * Deliver the signal to listening signalfds. This must be called - * with the sighand lock held. - */ - signalfd_notify(p, sig); - - 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: - unlock_task_sighand(p, &flags); -out_err: - rcu_read_unlock(); + if (!list_empty(&q->list)) + q = NULL; + spin_unlock_irqrestore(lock, flags); - return ret; + if (q) + __sigqueue_free(q); } -int -send_group_sigqueue(int sig, struct sigqueue *q, struct task_struct *p) +int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group) { + int sig = q->info.si_signo; + struct sigpending *pending; unsigned long flags; - int ret = 0; + int ret; BUG_ON(!(q->flags & SIGQUEUE_PREALLOC)); - read_lock(&tasklist_lock); - /* Since it_lock is held, p->sighand cannot be NULL. */ - spin_lock_irqsave(&p->sighand->siglock, flags); - handle_stop_signal(sig, p); + ret = -1; + if (!likely(lock_task_sighand(t, &flags))) + goto ret; - /* Short-circuit ignored signals. */ - if (sig_ignored(p, sig)) { - ret = 1; + ret = 1; /* the signal is ignored */ + if (!prepare_signal(sig, t)) goto out; - } + ret = 0; 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. + * the overrun count. */ BUG_ON(q->info.si_code != SI_TIMER); q->info.si_overrun++; goto out; - } - /* - * Deliver the signal to listening signalfds. This must be called - * with the sighand lock held. - */ - signalfd_notify(p, sig); - - /* - * Put this signal on the shared-pending queue. - * We always use the shared queue for process-wide signals, - * to avoid several races. - */ - list_add_tail(&q->list, &p->signal->shared_pending.list); - sigaddset(&p->signal->shared_pending.signal, sig); + } + q->info.si_overrun = 0; - __group_complete_signal(sig, p); + signalfd_notify(t, sig); + pending = group ? &t->signal->shared_pending : &t->pending; + list_add_tail(&q->list, &pending->list); + sigaddset(&pending->signal, sig); + complete_signal(sig, t, group); out: - spin_unlock_irqrestore(&p->sighand->siglock, flags); - read_unlock(&tasklist_lock); + unlock_task_sighand(t, &flags); +ret: return ret; } @@ -1408,13 +1329,16 @@ static inline void __wake_up_parent(struct task_struct *p, /* * Let a parent know about the death of a child. * For a stopped/continued status change, use do_notify_parent_cldstop instead. + * + * Returns -1 if our parent ignored us and so we've switched to + * self-reaping, or else @sig. */ - -void do_notify_parent(struct task_struct *tsk, int sig) +int do_notify_parent(struct task_struct *tsk, int sig) { struct siginfo info; unsigned long flags; struct sighand_struct *psig; + int ret = sig; BUG_ON(sig == -1); @@ -1444,10 +1368,9 @@ void do_notify_parent(struct task_struct *tsk, int sig) 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, + info.si_utime = cputime_to_clock_t(cputime_add(tsk->utime, tsk->signal->utime)); - info.si_stime = cputime_to_jiffies(cputime_add(tsk->stime, + info.si_stime = cputime_to_clock_t(cputime_add(tsk->stime, tsk->signal->stime)); info.si_status = tsk->exit_code & 0x7f; @@ -1480,14 +1403,16 @@ void do_notify_parent(struct task_struct *tsk, int sig) * is implementation-defined: we do (if you don't want * it, just use SIG_IGN instead). */ - tsk->exit_signal = -1; + ret = tsk->exit_signal = -1; if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) - sig = 0; + sig = -1; } if (valid_signal(sig) && sig > 0) __group_send_sig_info(sig, &info, tsk->parent); __wake_up_parent(tsk, tsk->parent); spin_unlock_irqrestore(&psig->siglock, flags); + + return ret; } static void do_notify_parent_cldstop(struct task_struct *tsk, int why) @@ -1515,9 +1440,8 @@ static void do_notify_parent_cldstop(struct task_struct *tsk, int why) 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_utime = cputime_to_clock_t(tsk->utime); + info.si_stime = cputime_to_clock_t(tsk->stime); info.si_code = why; switch (why) { @@ -1556,10 +1480,10 @@ static inline int may_ptrace_stop(void) * is a deadlock situation, and pointless because our tracer * is dead so don't allow us to stop. * If SIGKILL was already sent before the caller unlocked - * ->siglock we must see ->core_waiters != 0. Otherwise it + * ->siglock we must see ->core_state != NULL. Otherwise it * is safe to enter schedule(). */ - if (unlikely(current->mm->core_waiters) && + if (unlikely(current->mm->core_state) && unlikely(current->mm == current->parent->mm)) return 0; @@ -1572,9 +1496,8 @@ static inline int may_ptrace_stop(void) */ static int sigkill_pending(struct task_struct *tsk) { - return ((sigismember(&tsk->pending.signal, SIGKILL) || - sigismember(&tsk->signal->shared_pending.signal, SIGKILL)) && - !unlikely(sigismember(&tsk->blocked, SIGKILL))); + return sigismember(&tsk->pending.signal, SIGKILL) || + sigismember(&tsk->signal->shared_pending.signal, SIGKILL); } /* @@ -1590,8 +1513,6 @@ static int sigkill_pending(struct task_struct *tsk) */ static void ptrace_stop(int exit_code, int clear_code, siginfo_t *info) { - int killed = 0; - if (arch_ptrace_stop_needed(exit_code, info)) { /* * The arch code has something special to do before a @@ -1607,7 +1528,8 @@ static void ptrace_stop(int exit_code, int clear_code, siginfo_t *info) spin_unlock_irq(¤t->sighand->siglock); arch_ptrace_stop(exit_code, info); spin_lock_irq(¤t->sighand->siglock); - killed = sigkill_pending(current); + if (sigkill_pending(current)) + return; } /* @@ -1624,7 +1546,7 @@ static void ptrace_stop(int exit_code, int clear_code, siginfo_t *info) __set_current_state(TASK_TRACED); spin_unlock_irq(¤t->sighand->siglock); read_lock(&tasklist_lock); - if (!unlikely(killed) && may_ptrace_stop()) { + if (may_ptrace_stop()) { do_notify_parent_cldstop(current, CLD_TRAPPED); read_unlock(&tasklist_lock); schedule(); @@ -1688,7 +1610,7 @@ finish_stop(int stop_count) * 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)) { + if (tracehook_notify_jctl(stop_count == 0, CLD_STOPPED)) { read_lock(&tasklist_lock); do_notify_parent_cldstop(current, CLD_STOPPED); read_unlock(&tasklist_lock); @@ -1724,7 +1646,7 @@ static int do_signal_stop(int signr) struct task_struct *t; if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED) || - unlikely(sig->group_exit_task)) + unlikely(signal_group_exit(sig))) return 0; /* * There is no group stop already in progress. @@ -1799,8 +1721,9 @@ static int ptrace_signal(int signr, siginfo_t *info, int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka, struct pt_regs *regs, void *cookie) { - sigset_t *mask = ¤t->blocked; - int signr = 0; + struct sighand_struct *sighand = current->sighand; + struct signal_struct *signal = current->signal; + int signr; relock: /* @@ -1811,26 +1734,61 @@ relock: */ try_to_freeze(); - spin_lock_irq(¤t->sighand->siglock); + spin_lock_irq(&sighand->siglock); + /* + * Every stopped thread goes here after wakeup. Check to see if + * we should notify the parent, prepare_signal(SIGCONT) encodes + * the CLD_ si_code into SIGNAL_CLD_MASK bits. + */ + if (unlikely(signal->flags & SIGNAL_CLD_MASK)) { + int why = (signal->flags & SIGNAL_STOP_CONTINUED) + ? CLD_CONTINUED : CLD_STOPPED; + signal->flags &= ~SIGNAL_CLD_MASK; + spin_unlock_irq(&sighand->siglock); + + if (unlikely(!tracehook_notify_jctl(1, why))) + goto relock; + + read_lock(&tasklist_lock); + do_notify_parent_cldstop(current->group_leader, why); + read_unlock(&tasklist_lock); + goto relock; + } + for (;;) { struct k_sigaction *ka; - if (unlikely(current->signal->group_stop_count > 0) && + if (unlikely(signal->group_stop_count > 0) && do_signal_stop(0)) goto relock; - signr = dequeue_signal(current, mask, info); - - if (!signr) - break; /* will return 0 */ + /* + * Tracing can induce an artifical signal and choose sigaction. + * The return value in @signr determines the default action, + * but @info->si_signo is the signal number we will report. + */ + signr = tracehook_get_signal(current, regs, info, return_ka); + if (unlikely(signr < 0)) + goto relock; + if (unlikely(signr != 0)) + ka = return_ka; + else { + signr = dequeue_signal(current, ¤t->blocked, + info); - if (signr != SIGKILL) { - signr = ptrace_signal(signr, info, regs, cookie); if (!signr) - continue; + break; /* will return 0 */ + + if (signr != SIGKILL) { + signr = ptrace_signal(signr, info, + regs, cookie); + if (!signr) + continue; + } + + ka = &sighand->action[signr-1]; } - ka = ¤t->sighand->action[signr-1]; if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */ continue; if (ka->sa.sa_handler != SIG_DFL) { @@ -1852,7 +1810,8 @@ relock: /* * Global init gets no signals it doesn't want. */ - if (is_global_init(current)) + if (unlikely(signal->flags & SIGNAL_UNKILLABLE) && + !signal_group_exit(signal)) continue; if (sig_kernel_stop(signr)) { @@ -1867,17 +1826,17 @@ relock: * We need to check for that and bail out if necessary. */ if (signr != SIGSTOP) { - spin_unlock_irq(¤t->sighand->siglock); + spin_unlock_irq(&sighand->siglock); /* signals can be posted during this window */ if (is_current_pgrp_orphaned()) goto relock; - spin_lock_irq(¤t->sighand->siglock); + spin_lock_irq(&sighand->siglock); } - if (likely(do_signal_stop(signr))) { + if (likely(do_signal_stop(info->si_signo))) { /* It released the siglock. */ goto relock; } @@ -1889,15 +1848,16 @@ relock: continue; } - spin_unlock_irq(¤t->sighand->siglock); + spin_unlock_irq(&sighand->siglock); /* * Anything else is fatal, maybe with a core dump. */ current->flags |= PF_SIGNALED; - if ((signr != SIGKILL) && print_fatal_signals) - print_fatal_signal(regs, signr); + if (sig_kernel_coredump(signr)) { + if (print_fatal_signals) + print_fatal_signal(regs, info->si_signo); /* * If it was able to dump core, this kills all * other threads in the group and synchronizes with @@ -1906,16 +1866,16 @@ relock: * 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); + do_coredump(info->si_signo, info->si_signo, regs); } /* * Death signals, no core dump. */ - do_group_exit(signr); + do_group_exit(info->si_signo); /* NOTREACHED */ } - spin_unlock_irq(¤t->sighand->siglock); + spin_unlock_irq(&sighand->siglock); return signr; } @@ -1954,7 +1914,7 @@ void exit_signals(struct task_struct *tsk) out: spin_unlock_irq(&tsk->sighand->siglock); - if (unlikely(group_stop)) { + if (unlikely(group_stop) && tracehook_notify_jctl(1, CLD_STOPPED)) { read_lock(&tasklist_lock); do_notify_parent_cldstop(tsk, CLD_STOPPED); read_unlock(&tasklist_lock); @@ -1965,8 +1925,6 @@ EXPORT_SYMBOL(recalc_sigpending); EXPORT_SYMBOL_GPL(dequeue_signal); EXPORT_SYMBOL(flush_signals); EXPORT_SYMBOL(force_sig); -EXPORT_SYMBOL(kill_proc); -EXPORT_SYMBOL(ptrace_notify); EXPORT_SYMBOL(send_sig); EXPORT_SYMBOL(send_sig_info); EXPORT_SYMBOL(sigprocmask); @@ -2241,7 +2199,7 @@ sys_rt_sigtimedwait(const sigset_t __user *uthese, } asmlinkage long -sys_kill(int pid, int sig) +sys_kill(pid_t pid, int sig) { struct siginfo info; @@ -2254,11 +2212,12 @@ sys_kill(int pid, int sig) return kill_something_info(sig, &info, pid); } -static int do_tkill(int tgid, int pid, int sig) +static int do_tkill(pid_t tgid, pid_t pid, int sig) { int error; struct siginfo info; struct task_struct *p; + unsigned long flags; error = -ESRCH; info.si_signo = sig; @@ -2267,22 +2226,24 @@ static int do_tkill(int tgid, int pid, int sig) info.si_pid = task_tgid_vnr(current); info.si_uid = current->uid; - read_lock(&tasklist_lock); + rcu_read_lock(); p = find_task_by_vpid(pid); if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) { error = check_kill_permission(sig, &info, p); /* * The null signal is a permissions and process existence * probe. No signal is actually delivered. + * + * If lock_task_sighand() fails we pretend the task dies + * after receiving the signal. The window is tiny, and the + * signal is private anyway. */ - if (!error && sig && p->sighand) { - spin_lock_irq(&p->sighand->siglock); - handle_stop_signal(sig, p); + if (!error && sig && lock_task_sighand(p, &flags)) { error = specific_send_sig_info(sig, &info, p); - spin_unlock_irq(&p->sighand->siglock); + unlock_task_sighand(p, &flags); } } - read_unlock(&tasklist_lock); + rcu_read_unlock(); return error; } @@ -2297,7 +2258,7 @@ static int do_tkill(int tgid, int pid, int sig) * 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) +asmlinkage long sys_tgkill(pid_t tgid, pid_t pid, int sig) { /* This is only valid for single tasks */ if (pid <= 0 || tgid <= 0) @@ -2310,7 +2271,7 @@ asmlinkage long sys_tgkill(int tgid, int pid, int sig) * Send a signal to only one task, even if it's a CLONE_THREAD task. */ asmlinkage long -sys_tkill(int pid, int sig) +sys_tkill(pid_t pid, int sig) { /* This is only valid for single tasks */ if (pid <= 0) @@ -2320,7 +2281,7 @@ sys_tkill(int pid, int sig) } asmlinkage long -sys_rt_sigqueueinfo(int pid, int sig, siginfo_t __user *uinfo) +sys_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t __user *uinfo) { siginfo_t info; @@ -2339,13 +2300,14 @@ sys_rt_sigqueueinfo(int pid, int sig, siginfo_t __user *uinfo) int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact) { + struct task_struct *t = current; struct k_sigaction *k; sigset_t mask; if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig))) return -EINVAL; - k = ¤t->sighand->action[sig-1]; + k = &t->sighand->action[sig-1]; spin_lock_irq(¤t->sighand->siglock); if (oact) @@ -2366,9 +2328,7 @@ int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact) * (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))) { - struct task_struct *t = current; + if (sig_handler_ignored(sig_handler(t, sig), sig)) { sigemptyset(&mask); sigaddset(&mask, sig); rm_from_queue_full(&mask, &t->signal->shared_pending); @@ -2623,7 +2583,7 @@ asmlinkage long sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize) current->state = TASK_INTERRUPTIBLE; schedule(); - set_thread_flag(TIF_RESTORE_SIGMASK); + set_restore_sigmask(); return -ERESTARTNOHAND; } #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */