On Thu, Dec 11, 2025 at 05:36:57PM +0900, Wolfram Sang wrote: > > > > Isn't there even prototype code from Dan Williams? > > > > > > "[PATCH 1/3] cdev: Finish the cdev api with queued mode support" > > > > > > https://lkml.org/lkml/2021/1/20/997 > > > > I mentioned that in my LPC talk in 2022 :-) I think we should merge that > > (or a rebased, possibly improved version of it). I've meant to try > > plumbing that series in V4L2 but couldn't find the time so far. > > Yes, you mentioned it in 2022 but maybe not everyone in this thread is > right now aware of it ;) The patch above got changes requested. I talked > to Dan very briefly about it at Maintainers Summit 2023 and he was also > open (back then) to pick it up again.
After discussing with Tzung-Bi today after his presentation (thank you Tzung-Bi for your time, it helped me understand the problem you're facing better), I wonder if this series is fixing the issue in the right place. At the core of the problem is a devm_kzalloc() call to allocate driver-specific data. That data structure is then referenced from a cdev, which can dereference is after it gets freed. It seems that reference-counting the data structure instead of using devm_kzalloc() could be a better solution. -- Regards, Laurent Pinchart
