signals: send_signal: be paranoid about signalfd_notify()

send_signal() shouldn't call signalfd_notify() if it then fails with -EAGAIN.
Harmless, just a paranoid cleanup.

Also remove the comment.  It is obsolete, signalfd_notify() was simplified and
does a simple wakeup.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Davide Libenzi <davidel@xmailserver.org>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/signal.c

@@ -772,13 +772,6 @@ static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
 	 */
 	if (legacy_queue(pending, sig))
 		return 0;
-
-	/*
-	 * Deliver the signal to listening signalfds. This must be called
-	 * with the sighand lock held.
-	 */
-	signalfd_notify(t, sig);
-
 	/*
 	 * fast-pathed signals for kernel-internal things like SIGSTOP
 	 * or SIGKILL.
@@ -828,6 +821,7 @@ static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
 	}
 
 out_set:
+	signalfd_notify(t, sig);
 	sigaddset(&pending->signal, sig);
 	complete_signal(sig, t, group);
 	return 0;