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[194.223.74.160]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3b0b32812a6sm1611635a91.11.2026.11.04.20.29.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Nov 2026 20:29:11 -0800 (PST) Date: Thu, 5 Nov 2026 12:29:05 +0800 From: Kent Gibson To: Bartosz Golaszewski Cc: Linus Walleij , Bartosz Golaszewski , Andy Shevchenko , Adrian Ambrozewicz , linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH 4/5] gpiolib: don't overwrite the entire flags field in gpiod_free_commit() Message-ID: <20261105042905.GB8436@rigel> References: <20261104-gpio-desc-flags-atomic-v1-0-e23cedf619ba@oss.qualcomm.com> <20261104-gpio-desc-flags-atomic-v1-4-e23cedf619ba@oss.qualcomm.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: <20261104-gpio-desc-flags-atomic-v1-4-e23cedf619ba@oss.qualcomm.com> On Wed, Nov 04, 2026 at 04:36:59PM +0100, Bartosz Golaszewski wrote: > Use gpiod_update_flags() to clear all request-related flags in one go > instead of risking racing with concurrent users and overwriting any > changes they could have done between READ_ONCE() and WRITE_ONCE(). > > Cc: stable@vger.kernel.org > Fixes: 35b545332b80 ("gpio: remove gpio_lock") > Signed-off-by: Bartosz Golaszewski > --- > drivers/gpio/gpiolib.c | 26 +++++++++++++------------- > 1 file changed, 13 insertions(+), 13 deletions(-) > > diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c > index 63b65b646fbcfa9ea0f724d1d3e1ac22ba28f638..28d4cf0cef70f437dc4271f82975d09dc55125ea 100644 > --- a/drivers/gpio/gpiolib.c > +++ b/drivers/gpio/gpiolib.c > @@ -2693,23 +2693,23 @@ void gpiod_free_commit(struct gpio_desc *desc) > if (guard.gc->free) > guard.gc->free(guard.gc, gpiod_hwgpio(desc)); > > - clear_bit(GPIOD_FLAG_ACTIVE_LOW, &flags); > - clear_bit(GPIOD_FLAG_REQUESTED, &flags); > - clear_bit(GPIOD_FLAG_OPEN_DRAIN, &flags); > - clear_bit(GPIOD_FLAG_OPEN_SOURCE, &flags); > - clear_bit(GPIOD_FLAG_PULL_UP, &flags); > - clear_bit(GPIOD_FLAG_PULL_DOWN, &flags); > - clear_bit(GPIOD_FLAG_BIAS_DISABLE, &flags); > - clear_bit(GPIOD_FLAG_EDGE_RISING, &flags); > - clear_bit(GPIOD_FLAG_EDGE_FALLING, &flags); > - clear_bit(GPIOD_FLAG_EVENT_CLOCK_REALTIME, &flags); > - clear_bit(GPIOD_FLAG_EVENT_CLOCK_HTE, &flags); > - clear_bit(GPIOD_FLAG_IS_HOGGED, &flags); > #ifdef CONFIG_OF_DYNAMIC > WRITE_ONCE(desc->hog, NULL); > #endif > desc_set_label(desc, NULL); > - WRITE_ONCE(desc->flags, flags); > + gpiod_update_flags(desc, > + BIT(GPIOD_FLAG_ACTIVE_LOW) | > + BIT(GPIOD_FLAG_REQUESTED) | > + BIT(GPIOD_FLAG_OPEN_DRAIN) | > + BIT(GPIOD_FLAG_OPEN_SOURCE) | > + BIT(GPIOD_FLAG_PULL_UP) | > + BIT(GPIOD_FLAG_PULL_DOWN) | > + BIT(GPIOD_FLAG_BIAS_DISABLE) | > + BIT(GPIOD_FLAG_EDGE_RISING) | > + BIT(GPIOD_FLAG_EDGE_FALLING) | > + BIT(GPIOD_FLAG_EVENT_CLOCK_REALTIME) | > + BIT(GPIOD_FLAG_EVENT_CLOCK_HTE) | > + BIT(GPIOD_FLAG_IS_HOGGED), 0); > #ifdef CONFIG_GPIO_CDEV > WRITE_ONCE(desc->debounce_period_us, 0); > #endif > Not directly related to your change, but the debounce_period_us is protected by the GPIOD_FLAG_REQUESTED flag, so it should be cleared before the flag, else it could potentially race with a new request. Not sure if you want to fix it here or in a separate patch. Cheers, Kent.