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>

1 files changed, 4 insertions, 5 deletions

diff --git a/kernel/signal.c b/kernel/signal.c
index 4a9d763f8922..1814e68e4de3 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1840,11 +1840,6 @@ relock:
 
         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 @@ relock:
                 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);