bus: arm-ccn: Move event cleanup routine

The function cleaning up an initialized event
was called from the "event_del" handler, instead
of being used as the "destroy" callback. In case of
events group allocation this caused NULL pointer
dereference (as events are added and deleted
multiple times then). Fixed now.
Signed-off-by: Pawel Moll <mail@pawelmoll.com>
Signed-off-by: Kevin Hilman <khilman@linaro.org>

drivers/bus/arm-ccn.c

@@ -586,6 +586,30 @@ static int arm_ccn_pmu_type_eq(u32 a, u32 b)
 	return 0;
 }
 
+static void arm_ccn_pmu_event_destroy(struct perf_event *event)
+{
+	struct arm_ccn *ccn = pmu_to_arm_ccn(event->pmu);
+	struct hw_perf_event *hw = &event->hw;
+
+	if (hw->idx == CCN_IDX_PMU_CYCLE_COUNTER) {
+		clear_bit(CCN_IDX_PMU_CYCLE_COUNTER, ccn->dt.pmu_counters_mask);
+	} else {
+		struct arm_ccn_component *source =
+				ccn->dt.pmu_counters[hw->idx].source;
+
+		if (CCN_CONFIG_TYPE(event->attr.config) == CCN_TYPE_XP &&
+				CCN_CONFIG_EVENT(event->attr.config) ==
+				CCN_EVENT_WATCHPOINT)
+			clear_bit(hw->config_base, source->xp.dt_cmp_mask);
+		else
+			clear_bit(hw->config_base, source->pmu_events_mask);
+		clear_bit(hw->idx, ccn->dt.pmu_counters_mask);
+	}
+
+	ccn->dt.pmu_counters[hw->idx].source = NULL;
+	ccn->dt.pmu_counters[hw->idx].event = NULL;
+}
+
 static int arm_ccn_pmu_event_init(struct perf_event *event)
 {
 	struct arm_ccn *ccn;
@@ -599,6 +623,7 @@ static int arm_ccn_pmu_event_init(struct perf_event *event)
 		return -ENOENT;
 
 	ccn = pmu_to_arm_ccn(event->pmu);
+	event->destroy = arm_ccn_pmu_event_destroy;
 
 	if (hw->sample_period) {
 		dev_warn(ccn->dev, "Sampling not supported!\n");
@@ -731,30 +756,6 @@ static int arm_ccn_pmu_event_init(struct perf_event *event)
 	return 0;
 }
 
-static void arm_ccn_pmu_event_free(struct perf_event *event)
-{
-	struct arm_ccn *ccn = pmu_to_arm_ccn(event->pmu);
-	struct hw_perf_event *hw = &event->hw;
-
-	if (hw->idx == CCN_IDX_PMU_CYCLE_COUNTER) {
-		clear_bit(CCN_IDX_PMU_CYCLE_COUNTER, ccn->dt.pmu_counters_mask);
-	} else {
-		struct arm_ccn_component *source =
-				ccn->dt.pmu_counters[hw->idx].source;
-
-		if (CCN_CONFIG_TYPE(event->attr.config) == CCN_TYPE_XP &&
-				CCN_CONFIG_EVENT(event->attr.config) ==
-				CCN_EVENT_WATCHPOINT)
-			clear_bit(hw->config_base, source->xp.dt_cmp_mask);
-		else
-			clear_bit(hw->config_base, source->pmu_events_mask);
-		clear_bit(hw->idx, ccn->dt.pmu_counters_mask);
-	}
-
-	ccn->dt.pmu_counters[hw->idx].source = NULL;
-	ccn->dt.pmu_counters[hw->idx].event = NULL;
-}
-
 static u64 arm_ccn_pmu_read_counter(struct arm_ccn *ccn, int idx)
 {
 	u64 res;
@@ -1027,8 +1028,6 @@ static int arm_ccn_pmu_event_add(struct perf_event *event, int flags)
 static void arm_ccn_pmu_event_del(struct perf_event *event, int flags)
 {
 	arm_ccn_pmu_event_stop(event, PERF_EF_UPDATE);
-
-	arm_ccn_pmu_event_free(event);
 }
 
 static void arm_ccn_pmu_event_read(struct perf_event *event)