commit 1be53963b0519bd3681749a9bed8b83aeb005cca
author Oleg Nesterov <oleg@redhat.com> Tue Dec 15 16:47:26 2009 -0800
committer Linus Torvalds <torvalds@linux-foundation.org> Wed Dec 16 07:20:09 2009 -0800
tree 0bc6497a8039021f781f1c902f59e6f71f772793
parent ad09750b51150ca87531b8790a379214a974c167

signals: check ->group_stop_count after tracehook_get_signal()

Move the call to do_signal_stop() down, after tracehook call.  This makes
->group_stop_count condition visible to tracers before do_signal_stop()
will participate in this group-stop.

Currently the patch has no effect, tracehook_get_signal() always returns 0.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
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>

kernel/signal.c

diff --git a/kernel/signal.c b/kernel/signal.c
index 4a9d763..1814e68 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1840,11 +1840,6 @@
 
 	for (;;) {
 		struct k_sigaction *ka;
-
-		if (unlikely(signal->group_stop_count > 0) &&
-		    do_signal_stop(0))
-			goto relock;
-
 		/*
 		 * Tracing can induce an artifical signal and choose sigaction.
 		 * The return value in @signr determines the default action,
@@ -1856,6 +1851,10 @@
 		if (unlikely(signr != 0))
 			ka = return_ka;
 		else {
+			if (unlikely(signal->group_stop_count > 0) &&
+			    do_signal_stop(0))
+				goto relock;
+
 			signr = dequeue_signal(current, &current->blocked,
 					       info);