[PATCH v1 2/5] PM: sleep: Remove unnecessary mutex lock when waiting on parent

[Saravana Kannan <saravanak@google.com>]

Locking is not needed to do get_device(dev->parent). We either get a NULL
(if the parent was cleared) or the actual parent. Also, when a device is
deleted (device_del()) and removed from the dpm_list, its completion
variable is also complete_all()-ed. So, we don't have to worry about
waiting indefinitely on a deleted parent device.

Signed-off-by: Saravana Kannan <saravanak@google.com>
---
 drivers/base/power/main.c | 13 ++-----------
 1 file changed, 2 insertions(+), 11 deletions(-)

diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index 86e51b9fefab..9b9b6088e56a 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -284,18 +284,9 @@ static bool dpm_wait_for_superior(struct device *dev, bool async)
 	 * counting the parent once more unless the device has been deleted
 	 * already (in which case return right away).
 	 */
-	mutex_lock(&dpm_list_mtx);
-
-	if (!device_pm_initialized(dev)) {
-		mutex_unlock(&dpm_list_mtx);
-		return false;
-	}
-
 	parent = get_device(dev->parent);
-
-	mutex_unlock(&dpm_list_mtx);
-
-	dpm_wait(parent, async);
+	if (device_pm_initialized(dev))
+		dpm_wait(parent, async);
 	put_device(parent);
 
 	dpm_wait_for_suppliers(dev, async);
-- 
2.47.0.338.g60cca15819-goog