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    Subject[PATCH 5.10 162/663] media: imx: Fix csc/scaler unregister
    Date
    From: Ezequiel Garcia <ezequiel@collabora.com>

    [ 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>
    ---
    drivers/staging/media/imx/imx-media-csc-scaler.c | 4 ----
    1 file changed, 4 deletions(-)

    diff --git a/drivers/staging/media/imx/imx-media-csc-scaler.c b/drivers/staging/media/imx/imx-media-csc-scaler.c
    index fab1155a5958c..63a0204502a8b 100644
    --- a/drivers/staging/media/imx/imx-media-csc-scaler.c
    +++ b/drivers/staging/media/imx/imx-media-csc-scaler.c
    @@ -869,11 +869,7 @@ 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 *
    --
    2.27.0


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