[PATCH 6/9] coresight: syscfg: Fix deadlock in cscfg_create_device() error path

[James Clark]

If device_register() fails, put_device() is called with cscfg_mutex
held. This calls cscfg_dev_release() which takes cscfg_mutex again and
deadlocks. Drop the mutex before calling put_device().

Fixes: 199380decc5f ("coresight: configfs: Fix unload of configurations on module exit")
Reported-by: Sashiko <sashiko-bot@xxxxxxxxxx>
Closes: https://sashiko.dev/#/bug/linux-e07a8e2f-c34e-4609-a667-9f294c6fcf29
Signed-off-by: James Clark <james.clark@xxxxxxxxxx>
---
 drivers/hwtracing/coresight/coresight-syscfg.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c
index f93150a1bee4..92aef8b9c734 100644
--- a/drivers/hwtracing/coresight/coresight-syscfg.c
+++ b/drivers/hwtracing/coresight/coresight-syscfg.c
@@ -1217,8 +1217,12 @@ static int cscfg_create_device(void)
 	dev->init_name = "cs_system_cfg";
 
 	err = device_register(dev);
-	if (err)
+	if (err) {
+		/* cscfg_dev_release() takes cscfg_mutex */
+		mutex_unlock(&cscfg_mutex);
 		put_device(dev);
+		return err;
+	}
 
 create_dev_exit_unlock:
 	mutex_unlock(&cscfg_mutex);

-- 
2.43.0