| Message ID | 20210609115457.822085-2-paul.kocialkowski@bootlin.com |
|---|---|
| State | New |
| Headers | show |
| Series | None | expand |
Hi Paul, On Wed, Jun 09, 2021 at 01:54:57PM +0200, Paul Kocialkowski wrote: > A dedicated subdev notified is registered when using the helper > dedicated to sensors (v4l2_async_register_subdev_sensor_common), > but this is not the case when a driver uses v4l2_async_register_subdev > directly. Is this a problem? The notifier unregistration and cleanup functions should be safe to call on a notifier that's not been initialised or registered. The same goes for kfree with NULL argument.
Hi Sakari, On Wed 09 Jun 21, 15:27, Sakari Ailus wrote: > Hi Paul, > > On Wed, Jun 09, 2021 at 01:54:57PM +0200, Paul Kocialkowski wrote: > > A dedicated subdev notified is registered when using the helper > > dedicated to sensors (v4l2_async_register_subdev_sensor_common), > > but this is not the case when a driver uses v4l2_async_register_subdev > > directly. > > Is this a problem? > > The notifier unregistration and cleanup functions should be safe to call on > a notifier that's not been initialised or registered. The same goes for > kfree with NULL argument. I think you're right, the functions and kfree are indeed safe. I think I mixed things up with debugging an issue and assumed this was part of the fix I needed. Sorry for the noise! Paul
diff --git a/drivers/media/v4l2-core/v4l2-async.c b/drivers/media/v4l2-core/v4l2-async.c index cd9e78c63791..e0f4f7551ff3 100644 --- a/drivers/media/v4l2-core/v4l2-async.c +++ b/drivers/media/v4l2-core/v4l2-async.c @@ -780,10 +780,12 @@ void v4l2_async_unregister_subdev(struct v4l2_subdev *sd) mutex_lock(&list_lock); - __v4l2_async_notifier_unregister(sd->subdev_notifier); - __v4l2_async_notifier_cleanup(sd->subdev_notifier); - kfree(sd->subdev_notifier); - sd->subdev_notifier = NULL; + if (sd->subdev_notifier) { + __v4l2_async_notifier_unregister(sd->subdev_notifier); + __v4l2_async_notifier_cleanup(sd->subdev_notifier); + kfree(sd->subdev_notifier); + sd->subdev_notifier = NULL; + } if (sd->asd) { struct v4l2_async_notifier *notifier = sd->notifier;
A dedicated subdev notified is registered when using the helper dedicated to sensors (v4l2_async_register_subdev_sensor_common), but this is not the case when a driver uses v4l2_async_register_subdev directly. As a result, add a conditional check to deal with the dedicated subdev notifier only when necessary at the async subdev unregister step (and avoid operating on/freeing an unallocated notifier). Fixes: aef69d54755d ("media: v4l: fwnode: Add a convenience function for registering sensors") Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com> --- drivers/media/v4l2-core/v4l2-async.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)