[PATCH] do_sigaction: don't worry about signal_pending()

[Oleg Nesterov <oleg@tv-sign.ru>]

do_sigaction() returns -ERESTARTNOINTR if signal_pending(). The comment says:

	* If there might be a fatal signal pending on multiple
	* threads, make sure we take it before changing the action.
	
I think this is not needed. We should only worry about SIGNAL_GROUP_EXIT case,
bit it implies a pending SIGKILL which can't be cleared by do_sigaction.

Kill this special case.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>

--- t/kernel/signal.c~SA_NOPEND	2007-08-20 19:40:31.000000000 +0400
+++ t/kernel/signal.c	2007-08-20 19:43:41.000000000 +0400
@@ -2300,15 +2300,6 @@ int do_sigaction(int sig, struct k_sigac
 	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;