perf: Fix child event initial state setup

Currently we initialize the child event based on the original
parent state. This is wrong, because the original parent event
(and its state) is not related to current fork and also could
be already gone.

We need to initialize the child state based on the immediate
parent event state.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1410520708-19275-2-git-send-email-jolsa@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 15e58d4ea0353220c939f234b260142bdf750edf..132524c8b34037de070fb65829642d7829157544 100644 (file)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7818,6 +7818,7 @@ inherit_event(struct perf_event *parent_event,
              struct perf_event *group_leader,
              struct perf_event_context *child_ctx)
 {
+       enum perf_event_active_state parent_state = parent_event->state;
        struct perf_event *child_event;
        unsigned long flags;
 
@@ -7851,7 +7852,7 @@ inherit_event(struct perf_event *parent_event,
         * not its attr.disabled bit.  We hold the parent's mutex,
         * so we won't race with perf_event_{en, dis}able_family.
         */
-       if (parent_event->state >= PERF_EVENT_STATE_INACTIVE)
+       if (parent_state >= PERF_EVENT_STATE_INACTIVE)
                child_event->state = PERF_EVENT_STATE_INACTIVE;
        else
                child_event->state = PERF_EVENT_STATE_OFF;