On 8/2/22 14:26, Andy Shevchenko wrote: > On Tue, Aug 2, 2022 at 2:23 PM Andy Shevchenko > <andy.shevchenko@xxxxxxxxx> wrote: >> On Tue, Aug 2, 2022 at 2:21 PM Andy Shevchenko >> <andy.shevchenko@xxxxxxxxx> wrote: > > ... > >>> You are blaming the wrong man here, i.e. devm. The problem as I stated >>> above is developers who do not understand (pay attention to) the >>> lifetime of the objects. >> >> That said, the devm has nothing to do with the driver still being >> problematic for the scenario you described, no? > > And the cleanest (at the first glance) solution is to make v4l2 to fix > this bug by suppressing unbind attributes when the device is opened > for all v4l2 subdev drivers, and restore it back when it's closed. > Why would we do that? The patch works in the scenario that I described: the memory is freed in the struct video_device release() callback, which is called when the last reference to the video node goes away. This is standard V4L2 framework behavior that works great in the case of a unbind. Without devm_kzalloc it works fine, even when unbind is called. With devm_kzalloc the unbind attributes would have to be suppressed. I see no reason for that as media maintainer. Regards, Hans
