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McKenney" , Herve Codina , Jia Jia , linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v5 1/7] gpiolib: wait for pending label frees before cleaning up desc_srcu Message-ID: References: <20261103-gpiolib-chip-removal-v5-0-aambrozewicz@nvidia.com> <20261103-gpiolib-chip-removal-v5-1-aambrozewicz@nvidia.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261103-gpiolib-chip-removal-v5-1-aambrozewicz@nvidia.com> Organization: Intel Finland Oy - BIC 0357606-4 - c/o Alberga Business Park, 6 krs, Bertel Jungin Aukio 5, 02600 Espoo On Tue, Nov 03, 2026 at 12:32:34PM +0200, Adrian Ambrozewicz wrote: > desc_set_label() frees the old label with call_srcu() on > gdev->desc_srcu, and gpiodev_release() calls synchronize_srcu() before > cleanup_srcu_struct(). synchronize_srcu() waits for a grace period, not > for queued callbacks. Once the srcu_struct uses per-CPU callback lists, > a label freed by gpiochip_free_hogs() can still be pending, and > cleanup_srcu_struct() warns: > > WARNING: kernel/rcu/srcutree.c:706 at cleanup_srcu_struct+0x239/0x330, CPU#0: init/1 > Call Trace: > gpiodev_release > device_release > kobject_put > devres_release_all > device_release_driver_internal > platform_device_unregister > gpio_sim_device_deactivate > > Use srcu_barrier(), which waits for them. > > Reproduced with a hogged gpio-sim line, setting the chip live and back > on a 4-CPU guest with srcutree.convert_to_big=1: it warns within 60 > cycles; with this change, 1000 cycles pass. ... > Assisted-by: LLM This tag is obsoleted. Instead explain under '---' how AI has been used to generate this contribution. -- With Best Regards, Andy Shevchenko