perf: fix the missing event initialization when pmu is found in idr

[Lin Ming <ming.m.lin@intel.com>]

Currently, the event is not initialized if pmu is found in idr.
This never causes bug just because now no pmu is associated with the idr
id.
This patch fixes the potential bug.

Signed-off-by: Lin Ming <ming.m.lin@intel.com>
---
 kernel/perf_event.c |    9 +++++++--
 1 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 64a018e..821ce82 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -6098,17 +6098,22 @@ struct pmu *perf_init_event(struct perf_event *event)
 {
 	struct pmu *pmu = NULL;
 	int idx;
+	int ret;
 
 	idx = srcu_read_lock(&pmus_srcu);
 
 	rcu_read_lock();
 	pmu = idr_find(&pmu_idr, event->attr.type);
 	rcu_read_unlock();
-	if (pmu)
+	if (pmu) {
+		ret = pmu->event_init(event);
+		if (ret)
+			pmu = ERR_PTR(ret);
 		goto unlock;
+	}
 
 	list_for_each_entry_rcu(pmu, &pmus, entry) {
-		int ret = pmu->event_init(event);
+		ret = pmu->event_init(event);
 		if (!ret)
 			goto unlock;