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 <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Signed-off-by: Ingo Molnar <[email protected]>

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 9de4d352ba8cdc3a7ba222929f76715114baa709..6759f2a332d76f1fe513fec3946e441e754a94f9 100644 (file)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -8489,6 +8489,8 @@ SYSCALL_DEFINE5(perf_event_open,
        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 @@ SYSCALL_DEFINE5(perf_event_open,
 
        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);