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Sat, 23 Apr 2022 11:30:25 +0100 Date: Sat, 23 Apr 2022 11:30:25 +0100 Message-ID: <874k2kccse.wl-maz@kernel.org> From: Marc Zyngier To: Linus Walleij Cc: linux-kernel@vger.kernel.org, Bartosz Golaszewski , Thierry Reding , Joey Gouly , Jonathan Hunter , Hector Martin , Sven Peter , Alyssa Rosenzweig , Bjorn Andersson , Andy Gross , Jeffrey Hugo , Thomas Gleixner , Basavaraj Natikar , Shyam Sundar S K , Andy Shevchenko , linux-gpio@vger.kernel.org, linux-tegra@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-arm-msm@vger.kernel.org, kernel-team@android.com Subject: Re: [PATCH v3 00/10] gpiolib: Handle immutable irq_chip structures In-Reply-To: References: <20220419141846.598305-1-maz@kernel.org> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: linus.walleij@linaro.org, linux-kernel@vger.kernel.org, brgl@bgdev.pl, thierry.reding@gmail.com, joey.gouly@arm.com, jonathanh@nvidia.com, marcan@marcan.st, sven@svenpeter.dev, alyssa@rosenzweig.io, bjorn.andersson@linaro.org, agross@kernel.org, jeffrey.l.hugo@gmail.com, tglx@linutronix.de, Basavaraj.Natikar@amd.com, Shyam-sundar.S-k@amd.com, andy.shevchenko@gmail.com, linux-gpio@vger.kernel.org, linux-tegra@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-arm-msm@vger.kernel.org, kernel-team@android.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220423_033029_672106_EF272AA9 X-CRM114-Status: GOOD ( 32.95 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, 22 Apr 2022 22:24:22 +0100, Linus Walleij wrote: > > On Tue, Apr 19, 2022 at 4:19 PM Marc Zyngier wrote: > > > This is a followup from [2]. > > > > I recently realised that the gpiolib play ugly tricks on the > > unsuspecting irq_chip structures by patching the callbacks. > > > > Not only this breaks when an irq_chip structure is made const (which > > really should be the default case), but it also forces this structure > > to be copied at nauseam for each instance of the GPIO block, which is > > a waste of memory. > > > > My current approach is to add a new irq_chip flag (IRQCHIP_IMMUTABLE) > > which does what it says on the tin: don't you dare writing to them. > > Gpiolib is further updated not to install its own callbacks, and it > > becomes the responsibility of the driver to call into the gpiolib when > > required. This is similar to what we do for other subsystems such as > > PCI-MSI. > > > > 5 drivers are updated to this new model: M1, QC, Tegra, pl061 and AMD > > (as I actively use them) keeping a single irq_chip structure, marking > > it const, and exposing the new flag. > > > > Nothing breaks, the volume of change is small, the memory usage goes > > down and we have fewer callbacks that can be used as attack vectors. > > What's not to love? > > > > Since there wasn't any objection in the previous round of review, I'm > > going to take this series into -next to see if anything breaks at > > scale. > > The series: > Acked-by: Linus Walleij > > Bartosz: if you're happy with this can you apply it to an immutable branch > from v5.18-rc1 and merge that into the GPIO for-next and then I can also > pull that into pinctrl? For what it is worth, I've pushed this branch into irqchip-next. You can pick it up from: https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/log/?h=irq/gpio-immutable but I can also drop it from the irqchip tree. Just let me know. M. -- Without deviation from the norm, progress is not possible. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel