[PATCH v2] coresight: etm-perf: Fix reference count leak in etm_setup_aux

[Ma Ke <make24@iscas.ac.cn>]

In etm_setup_aux(), when a user sink is obtained via
coresight_get_sink_by_id(), it increments the reference count of the
sink device. However, if the sink is used in path building, the path
holds a reference, but the initial reference from
coresight_get_sink_by_id() is not released, causing a reference count
leak. We should release the initial reference after the path is built.

Found by code review.

Cc: stable@vger.kernel.org
Fixes: 0e6c20517596 ("coresight: etm-perf: Allow an event to use different sinks")
Signed-off-by: Ma Ke <make24@iscas.ac.cn>
---
Changes in v2:
- modified the patch as suggestions.
---
 drivers/hwtracing/coresight/coresight-etm-perf.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c
index f677c08233ba..8a5a59434cc9 100644
--- a/drivers/hwtracing/coresight/coresight-etm-perf.c
+++ b/drivers/hwtracing/coresight/coresight-etm-perf.c
@@ -454,6 +454,11 @@ static void *etm_setup_aux(struct perf_event *event, void **pages,
 		goto err;
 
 out:
+	if (user_sink) {
+		put_device(&user_sink->dev);
+		user_sink = NULL;
+	}
+
 	return event_data;
 
 err:
-- 
2.17.1