[RFC 2/3] drm/i915/pmu: Move i915 reference drop to new event->free()

[Tvrtko Ursulin]

From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>

Avoids use after free in the perf core code on the event destruction
path, after the PCI driver has been unbound with the active perf file
descriptors.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@xxxxxxxxx>
Cc: Aravind Iddamsetty <aravind.iddamsetty@xxxxxxxxxxxxxxx>
---
 drivers/gpu/drm/i915/i915_pmu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
index 21eb0c5b320d..010763a5bc39 100644
--- a/drivers/gpu/drm/i915/i915_pmu.c
+++ b/drivers/gpu/drm/i915/i915_pmu.c
@@ -514,7 +514,7 @@ static enum hrtimer_restart i915_sample(struct hrtimer *hrtimer)
 	return HRTIMER_RESTART;
 }
 
-static void i915_pmu_event_destroy(struct perf_event *event)
+static void i915_pmu_event_free(struct perf_event *event)
 {
 	struct i915_pmu *pmu = event_to_pmu(event);
 	struct drm_i915_private *i915 = pmu_to_i915(pmu);
@@ -630,7 +630,7 @@ static int i915_pmu_event_init(struct perf_event *event)
 
 	if (!event->parent) {
 		drm_dev_get(&i915->drm);
-		event->destroy = i915_pmu_event_destroy;
+		event->free = i915_pmu_event_free;
 	}
 
 	return 0;
-- 
2.40.1