On Wed Mar 19 16:02:48 2025 +0800, Ma Ke wrote:
> 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: sta...@vger.kernel.org
> Fixes: dc93a70cc7f9 ("V4L/DVB (9973): v4l2-dev: use the release callback from
> device instead of cdev")
> Signed-off-by: Ma Ke <mak...@iscas.ac.cn>
> Reviewed-by: Sakari Ailus <sakari.ai...@linux.intel.com>
> Signed-off-by: Hans Verkuil <hverk...@xs4all.nl>
Patch committed.
Thanks,
Hans Verkuil
drivers/media/v4l2-core/v4l2-dev.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
---
diff --git a/drivers/media/v4l2-core/v4l2-dev.c
b/drivers/media/v4l2-core/v4l2-dev.c
index b40c08ce909d..c369235113d9 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);
