signals: unify send_sigqueue/send_group_sigqueue completely

Suggested by Pavel Emelyanov.

send_sigqueue/send_group_sigqueue are only differ in how they lock ->siglock.
Unify them.  send_group_sigqueue() uses spin_lock() because it knows the task
can't exit, but in that case lock_task_sighand() can't fail and doesn't hurt.

Note that the "sig" argument is ignored, it is always equal to ->si_signo.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/kernel/signal.c b/kernel/signal.c
index 87424f7..367c666 100644 (file)
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1240,14 +1240,27 @@ void sigqueue_free(struct sigqueue *q)
        __sigqueue_free(q);
 }
 
-static int do_send_sigqueue(int sig, struct sigqueue *q, struct task_struct *t,
+static int do_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;
 
        BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
+
+       ret = -1;
+       if (!likely(lock_task_sighand(t, &flags)))
+               goto ret;
+
        handle_stop_signal(sig, t);
 
+       ret = 1;
+       if (sig_ignored(t, sig))
+               goto out;
+
+       ret = 0;
        if (unlikely(!list_empty(&q->list))) {
                /*
                 * If an SI_TIMER entry is already queue just increment
@@ -1256,58 +1269,29 @@ static int do_send_sigqueue(int sig, struct sigqueue *q, struct task_struct *t,
 
                BUG_ON(q->info.si_code != SI_TIMER);
                q->info.si_overrun++;
-               return 0;
+               goto out;
        }
 
-       if (sig_ignored(t, sig))
-               return 1;
-
        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);
-
-       return 0;
+out:
+       unlock_task_sighand(t, &flags);
+ret:
+       return ret;
 }
 
 int send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
 {
-       unsigned long flags;
-       int ret = -1;
-
-       /*
-        * 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 (!likely(lock_task_sighand(p, &flags)))
-               goto out_err;
-
-       ret = do_send_sigqueue(sig, q, p, 0);
-
-       unlock_task_sighand(p, &flags);
-out_err:
-       return ret;
+       return do_send_sigqueue(q, p, 0);
 }
 
 int
 send_group_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
 {
-       unsigned long flags;
-       int ret;
-
-       /* Since it_lock is held, p->sighand cannot be NULL. */
-       spin_lock_irqsave(&p->sighand->siglock, flags);
-
-       ret = do_send_sigqueue(sig, q, p, 1);
-
-       spin_unlock_irqrestore(&p->sighand->siglock, flags);
-
-       return ret;
+       return do_send_sigqueue(q, p, 1);
 }
 
 /*