commit 78cd2c748f459739ff864dd9308c0f6caf7f6e41
author Peter Zijlstra <peterz@infradead.org> Mon Jan 25 14:08:45 2016 +0100
committer Ingo Molnar <mingo@kernel.org> Thu Jan 28 20:06:35 2016 +0100
tree b25470373d9ed5c038833854b466e3725a56cf68
parent 45c815f06b80031659c63d7b93e580015d6024dd

perf: Fix orphan hole

We should set event->owner before we install the event,
otherwise there is a hole where the target task can fork() and
we'll not inherit the event because it thinks the event is
orphaned.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/events/core.c

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 9de4d35..6759f2a 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -8489,6 +8489,8 @@
 	perf_event__header_size(event);
 	perf_event__id_header_size(event);
 
+	event->owner = current;
+
 	perf_install_in_context(ctx, event, event->cpu);
 	perf_unpin_context(ctx);
 
@@ -8498,8 +8500,6 @@
 
 	put_online_cpus();
 
-	event->owner = current;
-
 	mutex_lock(&current->perf_event_mutex);
 	list_add_tail(&event->owner_entry, &current->perf_event_list);
 	mutex_unlock(&current->perf_event_mutex);