[PATCH 3.19.y-ckt 102/164] perf: Fix inherited events vs. tracepoint filters

[Kamal Mostafa]

3.19.8-ckt11 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Peter Zijlstra <peterz at infradead.org>

commit b71b437eedaed985062492565d9d421d975ae845 upstream.

Arnaldo reported that tracepoint filters seem to misbehave (ie. not
apply) on inherited events.

The fix is obvious; filters are only set on the actual (parent)
event, use the normal pattern of using this parent event for filters.
This is safe because each child event has a reference to it.

Reported-by: Arnaldo Carvalho de Melo <acme at kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme at kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz at infradead.org>
Cc: Adrian Hunter <adrian.hunter at intel.com>
Cc: Arnaldo Carvalho de Melo <acme at redhat.com>
Cc: David Ahern <dsahern at gmail.com>
Cc: Frédéric Weisbecker <fweisbec at gmail.com>
Cc: Jiri Olsa <jolsa at kernel.org>
Cc: Jiri Olsa <jolsa at redhat.com>
Cc: Linus Torvalds <torvalds at linux-foundation.org>
Cc: Peter Zijlstra <peterz at infradead.org>
Cc: Steven Rostedt <rostedt at goodmis.org>
Cc: Thomas Gleixner <tglx at linutronix.de>
Cc: Wang Nan <wangnan0 at huawei.com>
Link: http://lkml.kernel.org/r/20151102095051.GN17308@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo at kernel.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 kernel/events/core.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 3527176..c4535e3 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6181,6 +6181,10 @@ static int perf_tp_filter_match(struct perf_event *event,
 {
 	void *record = data->raw->data;
 
+	/* only top level events have filters set */
+	if (event->parent)
+		event = event->parent;
+
 	if (likely(!event->filter) || filter_match_preds(event->filter, record))
 		return 1;
 	return 0;
-- 
1.9.1