1 files changed, 282 insertions, 364 deletions

diff --git a/kernel/signal.c b/kernel/signal.c
index 64ad0ed15992..72bb4f51f963 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -39,11 +39,19 @@
 
 static struct kmem_cache *sigqueue_cachep;
 
+static int __sig_ignored(struct task_struct *t, int sig)
+{
+        void __user *handler;
+
+        /* 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));
+}
 
 static int sig_ignored(struct task_struct *t, int sig)
 {
-        void __user * handler;
-
         /*
          * Tracers always want to know about signals..
          */
@@ -58,10 +66,7 @@ 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));
+        return __sig_ignored(t, sig);
 }
 
 /*
@@ -372,7 +377,7 @@ 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 +410,12 @@ 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
@@ -422,9 +431,7 @@ int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
                 if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT))
                         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
@@ -526,21 +533,34 @@ 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);
@@ -550,62 +570,44 @@ static int check_kill_permission(int sig, struct siginfo *info,
 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 +617,7 @@ 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 +628,163 @@ 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))
+                /*
+                 * There is just one thread and it does not need to be woken.
+                 * It will dequeue unblocked signals before it runs again.
+                 */
+                return;
+        else {
                 /*
-                 * Make sure that any pending stop signal already dequeued
-                 * is undone by the wakeup for SIGKILL.
+                 * Otherwise try to find a suitable thread.
                  */
-                p->signal->flags = 0;
+                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 || !(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.
+                         */
+                        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 +804,7 @@ 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 +834,12 @@ 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 +872,16 @@ 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 +892,8 @@ 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 +913,8 @@ 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 +928,6 @@ 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 +955,11 @@ 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 +970,7 @@ 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 +1019,6 @@ 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 +1032,8 @@ retry:
                          */
                         goto retry;
         }
-
-        if (unlikely(sig_needs_tasklist(sig)))
-                read_unlock(&tasklist_lock);
         rcu_read_unlock();
+
         return error;
 }
 
@@ -1159,8 +1130,7 @@ 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 +1145,9 @@ 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;
 }
 
@@ -1291,28 +1253,24 @@ void sigqueue_free(struct sigqueue *q)
         __sigqueue_free(q);
 }
 
-int send_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));
 
-        /*
-         * 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
-         */
-        rcu_read_lock();
+        ret = -1;
+        if (!likely(lock_task_sighand(t, &flags)))
+                goto ret;
 
-        if (!likely(lock_task_sighand(p, &flags))) {
-                ret = -1;
-                goto out_err;
-        }
+        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
@@ -1322,77 +1280,15 @@ int send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
                 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();
-
-        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);
-        /* Since it_lock is held, p->sighand cannot be NULL. */
-        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.
-                 */
-                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);
-
-        __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;
 }
 
@@ -1723,8 +1619,9 @@ static int do_signal_stop(int signr)
         } else {
                 struct task_struct *t;
 
-                if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED) ||
-                    unlikely(sig->group_exit_task))
+                if (unlikely((sig->flags & (SIGNAL_STOP_DEQUEUED | SIGNAL_UNKILLABLE))
+                                         != SIGNAL_STOP_DEQUEUED) ||
+                    unlikely(signal_group_exit(sig)))
                         return 0;
                 /*
                  * There is no group stop already in progress.
@@ -1799,8 +1696,9 @@ 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 = &current->blocked;
-        int signr = 0;
+        struct sighand_struct *sighand = current->sighand;
+        struct signal_struct *signal = current->signal;
+        int signr;
 
 relock:
         /*
@@ -1811,16 +1709,32 @@ relock:
          */
         try_to_freeze();
 
-        spin_lock_irq(&current->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);
+
+                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);
-
+                signr = dequeue_signal(current, &current->blocked, info);
                 if (!signr)
                         break; /* will return 0 */
 
@@ -1830,7 +1744,7 @@ relock:
                                 continue;
                 }
 
-                ka = &current->sighand->action[signr-1];
+                ka = &sighand->action[signr-1];
                 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing.  */
                         continue;
                 if (ka->sa.sa_handler != SIG_DFL) {
@@ -1852,7 +1766,8 @@ 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)) {
@@ -1867,14 +1782,14 @@ relock:
                          * We need to check for that and bail out if necessary.
                          */
                         if (signr != SIGSTOP) {
-                                spin_unlock_irq(&current->sighand->siglock);
+                                spin_unlock_irq(&sighand->siglock);
 
                                 /* signals can be posted during this window */
 
                                 if (is_current_pgrp_orphaned())
                                         goto relock;
 
-                                spin_lock_irq(&current->sighand->siglock);
+                                spin_lock_irq(&sighand->siglock);
                         }
 
                         if (likely(do_signal_stop(signr))) {
@@ -1889,15 +1804,16 @@ relock:
                         continue;
                 }
 
-                spin_unlock_irq(&current->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, signr);
                         /*
                          * If it was able to dump core, this kills all
                          * other threads in the group and synchronizes with
@@ -1915,7 +1831,7 @@ relock:
                 do_group_exit(signr);
                 /* NOTREACHED */
         }
-        spin_unlock_irq(&current->sighand->siglock);
+        spin_unlock_irq(&sighand->siglock);
         return signr;
 }
 
@@ -2259,6 +2175,7 @@ static int do_tkill(int tgid, int pid, int sig)
         int error;
         struct siginfo info;
         struct task_struct *p;
+        unsigned long flags;
 
         error = -ESRCH;
         info.si_signo = sig;
@@ -2267,22 +2184,24 @@ 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;
 }
@@ -2339,13 +2258,14 @@ 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 = &current->sighand->action[sig-1];
+        k = &t->sighand->action[sig-1];
 
         spin_lock_irq(&current->sighand->siglock);
         if (oact)
@@ -2366,9 +2286,7 @@ 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_ignored(t, sig)) {
                         sigemptyset(&mask);
                         sigaddset(&mask, sig);
                         rm_from_queue_full(&mask, &t->signal->shared_pending);
@@ -2623,7 +2541,7 @@ 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 */