From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2BAAD21A92F; Sat, 7 Feb 2026 14:00:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770472859; cv=none; b=FwxtnmLKzMHk18XBi6HtjgK0HkNGF+cEPn/QlLXhVAGUv/6uP4mE+CAx5o6bomhuUxXuMksxMbv6uxdsgJWpbr+betlaKtGskQTL4/7yWBWkHJbVnGkJMgJfkoSWIDQVfdZE1TZk9c13bYwfn0qLyr8c71fmqthqRHsYVI+EF+c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770472859; c=relaxed/simple; bh=ipmA27PT7L4J7VlPzxsEb8IpZwj1SopV4GIlkZpo15M=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=BdYeQJm4HeBf3V61W3l5lRmSENXl40L2SUuX6Cpx/QsfzDvTF/yohWaqbn66eZoKhBVjvwWH43XCObCzOHNahEbiIRijLSj+QwrpF5HhV09pAvKBpw4tUMrt2GxmjfHw9LZLbpxCUgNmHyrgmUqjj8HPboxpHIlLoW4RYoSHbOo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=DgLx2j9Q; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="DgLx2j9Q" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 09AA0C116D0; Sat, 7 Feb 2026 14:00:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770472858; bh=ipmA27PT7L4J7VlPzxsEb8IpZwj1SopV4GIlkZpo15M=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=DgLx2j9QiaTeIHfN5C/Ip4ZVAqDYFy4VSgcEwAdV551M6TIhtLIXYkeAhvP0vvHxb F3ozXf/gKDp0o5ABqFSnr23Lme3Y2svkzZcGSUhycf2h3joMYOVEgTYcZh1Y76zTKF cDmNIFUjYFK8dcLOJgKnmTngWlDGyuQulhOv4u4QRu/CFRfjdIxx3zLQNSefJ1qxLS Ji7EtF6ZD9mZgcealEUaeO2d+UhFVcq/g8RcV9eG5e3hjm6otW2YtI+60mu2Uger36 q6tSbwhXscCU0GjWe8fa072MreC1qaJBhwlenn/9A4Gk3y9hDE+Agkos4CBaQO0+Wu Z9C2hlbiL+ASA== Date: Sat, 7 Feb 2026 22:00:53 +0800 From: Tzung-Bi Shih To: Greg Kroah-Hartman Cc: Johan Hovold , "Rafael J . Wysocki" , Danilo Krummrich , Bartosz Golaszewski , Linus Walleij , Jonathan Corbet , Shuah Khan , Laurent Pinchart , Wolfram Sang , Simona Vetter , Dan Williams , Jason Gunthorpe , linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 0/3] Revert "revocable: Revocable resource management" Message-ID: References: <20260204142849.22055-1-johan@kernel.org> <2026020624-buddhism-clavicle-7a90@gregkh> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2026020624-buddhism-clavicle-7a90@gregkh> On Fri, Feb 06, 2026 at 04:13:00PM +0100, Greg Kroah-Hartman 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. Acknowledged. I'll start reworking this into a unified series that incorporates the feedback and lessons learned.