media: imx: Fix csc/scaler unregister

BugLink: https://bugs.launchpad.net/bugs/1918974
[ Upstream commit 89b14485caa4b7b2eaf70be0064f0978e68ebeee ]

The csc/scaler device private struct is released by
ipu_csc_scaler_video_device_release(), which can be called
by video_unregister_device() if there are no users
of the underlying struct video device.

Therefore, the mutex can't be held when calling
video_unregister_device() as its memory may be freed
by it, leading to a kernel oops.

Fortunately, the fix is quite simple as no locking
is needed when calling video_unregister_device(): v4l2-core
already has its own internal locking, and the structures
are also properly refcounted.

Fixes: a8ef0488cc59 ("media: imx: add csc/scaler mem2mem device")
Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kelsey Skunberg <kelsey.skunberg@canonical.com>

diff --git a/drivers/staging/media/imx/imx-media-csc-scaler.c b/drivers/staging/media/imx/imx-media-csc-scaler.c
index 2b635ebf62d6a88f22d4a0aeffae79cb60484780..a15d970adb983ff5b51f4fd5f4c45f932ad44632 100644 (file)
--- a/drivers/staging/media/imx/imx-media-csc-scaler.c
+++ b/drivers/staging/media/imx/imx-media-csc-scaler.c
@@ -866,11 +866,7 @@ void imx_media_csc_scaler_device_unregister(struct imx_media_video_dev *vdev)
        struct ipu_csc_scaler_priv *priv = vdev_to_priv(vdev);
        struct video_device *vfd = priv->vdev.vfd;
 
-       mutex_lock(&priv->mutex);
-
        video_unregister_device(vfd);
-
-       mutex_unlock(&priv->mutex);
 }
 
 struct imx_media_video_dev *