[PATCH 007/118] ARM: 7698/1: perf: fix group validation when using enable_on_exec

[Luis Henriques]

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

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

From: Will Deacon <will.deacon at arm.com>

commit cb2d8b342aa084d1f3ac29966245dec9163677fb upstream.

Events may be created with attr->disabled == 1 and attr->enable_on_exec
== 1, which confuses the group validation code because events with the
PERF_EVENT_STATE_OFF are not considered candidates for scheduling, which
may lead to failure at group scheduling time.

This patch fixes the validation check for ARM, so that events in the
OFF state are still considered when enable_on_exec is true.

Cc: Peter Zijlstra <a.p.zijlstra at chello.nl>
Cc: Arnaldo Carvalho de Melo <acme at ghostprotocols.net>
Cc: Jiri Olsa <jolsa at redhat.com>
Reported-by: Sudeep KarkadaNagesha <Sudeep.KarkadaNagesha at arm.com>
Signed-off-by: Will Deacon <will.deacon at arm.com>
Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>
[ luis: adjust context ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 arch/arm/kernel/perf_event.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c
index a02eada..952a5a7 100644
--- a/arch/arm/kernel/perf_event.c
+++ b/arch/arm/kernel/perf_event.c
@@ -319,7 +319,10 @@ validate_event(struct pmu_hw_events *hw_events,
 	struct hw_perf_event fake_event = event->hw;
 	struct pmu *leader_pmu = event->group_leader->pmu;
 
-	if (event->pmu != leader_pmu || event->state <= PERF_EVENT_STATE_OFF)
+	if (event->pmu != leader_pmu || event->state < PERF_EVENT_STATE_OFF)
+		return 1;
+
+	if (event->state == PERF_EVENT_STATE_OFF && !event->attr.enable_on_exec)
 		return 1;
 
 	return armpmu->get_event_idx(hw_events, &fake_event) >= 0;
-- 
1.8.1.2