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Sat, 15 Feb 2025 02:08:48 -0800 (PST) From: Bartosz Golaszewski To: Linus Walleij Cc: linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org, Bartosz Golaszewski Subject: [PATCH] gpiolib: read descriptor flags once in gpiolib_dbg_show() Date: Sat, 15 Feb 2025 11:08:47 +0100 Message-ID: <20250215100847.30136-1-brgl@bgdev.pl> X-Mailer: git-send-email 2.45.2 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Bartosz Golaszewski For consistency with most other code that can access requested descriptors: read the flags once atomically and then test individual bits from the helper variable. This avoids any potential discrepancies should flags change during the debug print. Signed-off-by: Bartosz Golaszewski --- drivers/gpio/gpiolib.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index f4e14a7dbc87..7dd054f8141e 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -5003,6 +5003,7 @@ static void gpiolib_dbg_show(struct seq_file *s, stru= ct gpio_device *gdev) unsigned int gpio =3D gdev->base; struct gpio_desc *desc; struct gpio_chip *gc; + unsigned long flags; int value; =20 guard(srcu)(&gdev->srcu); @@ -5015,12 +5016,13 @@ static void gpiolib_dbg_show(struct seq_file *s, st= ruct gpio_device *gdev) =20 for_each_gpio_desc(gc, desc) { guard(srcu)(&desc->gdev->desc_srcu); - is_irq =3D test_bit(FLAG_USED_AS_IRQ, &desc->flags); - if (is_irq || test_bit(FLAG_REQUESTED, &desc->flags)) { + flags =3D READ_ONCE(desc->flags); + is_irq =3D test_bit(FLAG_USED_AS_IRQ, &flags); + if (is_irq || test_bit(FLAG_REQUESTED, &flags)) { gpiod_get_direction(desc); - is_out =3D test_bit(FLAG_IS_OUT, &desc->flags); + is_out =3D test_bit(FLAG_IS_OUT, &flags); value =3D gpio_chip_get_value(gc, desc); - active_low =3D test_bit(FLAG_ACTIVE_LOW, &desc->flags); + active_low =3D test_bit(FLAG_ACTIVE_LOW, &flags); seq_printf(s, " gpio-%-3u (%-20.20s|%-20.20s) %s %s %s%s\n", gpio, desc->name ?: "", gpiod_get_label(desc), is_out ? "out" : "in ", --=20 2.45.2