Once device_register() failed, we should call put_device() to decrement reference count for cleanup. Or it could cause memory leak. And move callback function v4l2_device_release() and v4l2_device_get() before put_device().

As comment of device_register() says, 'NOTE: _Never_ directly free @dev after calling this function, even if it returned an error! Always use put_device() to give up the reference initialized in this function instead.'

Found by code review.

Cc: stable@vger.kernel.org Fixes: dc93a70cc7f9 ("V4L/DVB (9973): v4l2-dev: use the release callback from device instead of cdev") Signed-off-by: Ma Ke make24@iscas.ac.cn --- Changes in v3: - modified the patch to balance the v4l2_device reference count; - changed the Fix tag as suggestions; Changes in v2: - modified the patch as no callback function before put_device(). --- drivers/media/v4l2-core/v4l2-dev.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/media/v4l2-core/v4l2-dev.c b/drivers/media/v4l2-core/v4l2-dev.c index 5bcaeeba4d09..4c7e1008a152 100644 --- a/drivers/media/v4l2-core/v4l2-dev.c +++ b/drivers/media/v4l2-core/v4l2-dev.c @@ -1054,25 +1054,25 @@ int __video_register_device(struct video_device *vdev, vdev->dev.class = &video_class; vdev->dev.devt = MKDEV(VIDEO_MAJOR, vdev->minor); vdev->dev.parent = vdev->dev_parent; + vdev->dev.release = v4l2_device_release; dev_set_name(&vdev->dev, "%s%d", name_base, vdev->num); + + /* Increase v4l2_device refcount*/ + v4l2_device_get(vdev->v4l2_dev); + mutex_lock(&videodev_lock); ret = device_register(&vdev->dev); if (ret < 0) { mutex_unlock(&videodev_lock); pr_err("%s: device_register failed\n", __func__); - goto cleanup; + put_device(&vdev->dev); + return ret; } - /* Register the release callback that will be called when the last - reference to the device goes away. */ - vdev->dev.release = v4l2_device_release; - + if (nr != -1 && nr != vdev->num && warn_if_nr_in_use) pr_warn("%s: requested %s%d, got %s\n", __func__, name_base, nr, video_device_node_name(vdev));

- /* Increase v4l2_device refcount */ - v4l2_device_get(vdev->v4l2_dev); - /* Part 5: Register the entity. */ ret = video_register_media_controller(vdev);