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media: v4l2-dev: fix error handling in __video_register_device()

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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: dc93a70cc7 ("V4L/DVB (9973): v4l2-dev: use the release callback from device instead of cdev")
Signed-off-by: Ma Ke <make24@iscas.ac.cn>
Reviewed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
This commit is contained in:
Ma Ke 2025-03-19 16:02:48 +08:00 committed by Hans Verkuil
parent 48dbb76cef
commit 2a934fdb01
1 changed files with 7 additions and 7 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

14
drivers/media/v4l2-core/v4l2-dev.c
View file

@ -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);