On Fri, Feb 6, 2026 at 4:17 PM Greg Kroah-Hartman <[email protected]> wrote: > > On Wed, Feb 04, 2026 at 03:28:46PM +0100, Johan Hovold wrote: > > I was surprised to learn that the revocable functionality was merged the > > other > > week given the community feedback on list and at LPC, but not least since > > there > > are no users of it, which we are supposed to require to be able to evaluate > > it > > properly. > > > > The chromeos ec driver issue which motivated this work turned out not to > > need > > it as was found during review. And the example gpiolib conversion was posted > > the very same morning that this was merged which hardly provides enough time > > for evaluation (even if Bartosz quickly reported a performance regression). > > > > Turns out there are correctness issues with both the gpiolib conversion and > > the revocable design itself that can lead to use-after-free and hung tasks > > (see > > [1] and [2]). > > > > And as was pointed out repeatedly during review, and again at the day of the > > merge, this does not look like the right interface for the chardev unplug > > issue. > > > > Despite the last-minute attempt at addressing the issues mentioned above > > incrementally, the revocable design is still fundamentally flawed (see patch > > 3/3). > > > > We have processes like requiring a user before merging a new interface so > > that > > issues like these can be identified and the soundness of an API be > > evaluated. > > They also give a sense of when things are expected to happen, which allows > > our > > scarce reviewers to manage their time (e.g. to not be forced to drop > > everything > > else they are doing when things are merged prematurely). > > > > There really is no reason to exempt any new interface from this regardless > > of > > whether one likes the underlying concept or not. > > > > Revert the revocable implementation until a redesign has been proposed and > > evaluated properly. > > After thinking about this a lot, and talking it over with Danilo a bit, > I've applied this series that reverts these changes. > > Kernel developers / maintainers are only "allowed" one major argument / > fight a year, and I really don't want to burn my 2026 usage so early in > the year :) > > Tzung-Bi, can you take the feedback here, and what you have learned from > the gpio patch series, and rework this into a "clean" patch series for > us to review and comment on for future releases? That should give us > all a baseline on which to work off of, without having to worry about > the different versions/fixes floating around at the moment. >
I think it's a good decision. I definitely want to see it upstream but it needs a serious rework and I think it should go upstream together with the first user. I'm fine with it being the GPIO subsystem and happy to help with reviewing and development. Bartosz
