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>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
        k = ¤t->sighand->action[sig-1];
 
        spin_lock_irq(¤t->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(¤t->sighand->siglock);
-               return -ERESTARTNOINTR;
-       }
-
        if (oact)
                *oact = *k;