[PATCH 5.15.y] media: samsung: exynos4-is: fix potential ABBA deadlock on init

[Sasha Levin <sashal@kernel.org>]

From: Marek Szyprowski <m.szyprowski@samsung.com>

[ Upstream commit 17dc8ccd6dd5ffe30aa9b0d36e2af1389344ce2b ]

v4l2_device_register_subdev_nodes() must called without taking
media_dev->graph_mutex to avoid potential AB-BA deadlock on further
subdevice driver initialization.

Fixes: fa91f1056f17 ("[media] exynos4-is: Add support for asynchronous subdevices registration")
Cc: stable@vger.kernel.org
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/media/platform/exynos4-is/media-dev.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/media/platform/exynos4-is/media-dev.c b/drivers/media/platform/exynos4-is/media-dev.c
index b19d7c8ddc06..63868d1ae0d0 100644
--- a/drivers/media/platform/exynos4-is/media-dev.c
+++ b/drivers/media/platform/exynos4-is/media-dev.c
@@ -1411,12 +1411,14 @@ static int subdev_notifier_complete(struct v4l2_async_notifier *notifier)
 	mutex_lock(&fmd->media_dev.graph_mutex);
 
 	ret = fimc_md_create_links(fmd);
-	if (ret < 0)
-		goto unlock;
+	if (ret < 0) {
+		mutex_unlock(&fmd->media_dev.graph_mutex);
+		return ret;
+	}
 
-	ret = v4l2_device_register_subdev_nodes(&fmd->v4l2_dev);
-unlock:
 	mutex_unlock(&fmd->media_dev.graph_mutex);
+
+	ret = v4l2_device_register_subdev_nodes(&fmd->v4l2_dev);
 	if (ret < 0)
 		return ret;
 
-- 
2.51.0