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Tue, 25 Feb 2025 03:56:27 -0800 (PST) From: Bartosz Golaszewski Date: Tue, 25 Feb 2025 12:56:23 +0100 Subject: [PATCH 1/3] gpiolib: don't use gpiochip_get_direction() when registering a chip Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20250225-retval-fixes-v1-1-078c4c98517a@linaro.org> References: <20250225-retval-fixes-v1-0-078c4c98517a@linaro.org> In-Reply-To: <20250225-retval-fixes-v1-0-078c4c98517a@linaro.org> To: Linus Walleij , Bartosz Golaszewski , Marek Szyprowski , Andy Shevchenko Cc: linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org, Bartosz Golaszewski X-Mailer: b4 0.14.1 X-Developer-Signature: v=1; a=openpgp-sha256; l=2174; i=bartosz.golaszewski@linaro.org; h=from:subject:message-id; bh=+tTnhMWB//FVOHJTSSpSmVpKtdDSpnz0c6diDmew/A8=; b=owEBbAKT/ZANAwAKARGnLqAUcddyAcsmYgBnva/qaE2yAUg2nPQ80bDPUYDWPfZhWOnHAN7pY qlm6r0nnwOJAjIEAAEKAB0WIQQWnetsC8PEYBPSx58Rpy6gFHHXcgUCZ72v6gAKCRARpy6gFHHX cibLD/iHExBqkQIeiKBOZG4VnNjIxs1YVEE5mdFb/S3iCX1FqQOQGf0RtYlmobHe+qDPsOffAi9 vHyen5ZPfHRTH23hlXv3q3Ws7u9JYWqiHxe6GoyVingpQQBql7/QaFTp/KP2iKNtis40gYBD2de tqroqif9wuyf/oD+vzVWtoiq57V3GiyBumXrMyDE4PEEaTGjGfxxy/Gq54y9EjnnckJ65evQ9Dw LTuxE9zJyIU8+GTeBQad7NRUVjixItxOOpVFYKyMj6rbW6Itj2gD01oICXtoEWixRvRv/Cd1MMp B+wIGv/jM7g8WrhEBITkWGU3/03IYK3nQ8cgqgsIxDuSpyMnStL/WKOgaSXzvZubbTLxOSmTKyJ FrZS+hfKiOULzvU+KtC8lCS75o6LSjwmWd4S4nVGLHb313LaGVW907oO2sxqGb4D1wY88WAaIOp 6kI+Za0ln38bz4hj1Mo6BS9Db0AQGhq7sF5MXaBQg293Xzfen+M4c9mYtHDGVYC938WtybdwIYx qYICftwel4MTJH1r1jyZlmkJ/8NX9FAqqPD81XcKu8GizZ++rBabxHz/5YPrRNUvjlZkpk8kI45 IzlIE7FmL5xgBKq3kOprkFxelmyGxe9EftM1PBE5g102P/q0bBwUO9FesfvimS9X8YwiySHJgrf 9QxxPojpa1yRc X-Developer-Key: i=bartosz.golaszewski@linaro.org; a=openpgp; fpr=169DEB6C0BC3C46013D2C79F11A72EA01471D772 From: Bartosz Golaszewski During chip registration we should neither check the return value of gc->get_direction() nor hold the SRCU lock when calling it. The former is because pin controllers may have pins set to alternate functions and return errors from their get_direction() callbacks. That's alright - we should default to the safe INPUT state and not bail-out. The latter is not needed because we haven't registered the chip yet so there's nothing to protect against dynamic removal. In fact: we currently hit a lockdep splat. Revert to calling the gc->get_direction() callback directly not not checking its value. Fixes: 9d846b1aebbe ("gpiolib: check the return value of gpio_chip::get_dir= ection()") Fixes: e623c4303ed1 ("gpiolib: sanitize the return value of gpio_chip::get_= direction()") Reported-by: Marek Szyprowski Closes: https://lore.kernel.org/all/81f890fc-6688-42f0-9756-567efc8bb97a@sa= msung.com/ Signed-off-by: Bartosz Golaszewski Reviewed-by: Andy Shevchenko Tested-by: Marek Szyprowski --- drivers/gpio/gpiolib.c | 20 ++++---------------- 1 file changed, 4 insertions(+), 16 deletions(-) diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index e8678a6c82ea..31d400b10167 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -1082,24 +1082,12 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc= , void *data, =20 desc->gdev =3D gdev; =20 - if (gc->get_direction && gpiochip_line_is_valid(gc, desc_index)) { - ret =3D gpiochip_get_direction(gc, desc_index); - if (ret < 0) - /* - * FIXME: Bail-out here once all GPIO drivers - * are updated to not return errors in - * situations that can be considered normal - * operation. - */ - dev_warn(&gdev->dev, - "%s: get_direction failed: %d\n", - __func__, ret); - - assign_bit(FLAG_IS_OUT, &desc->flags, !ret); - } else { + if (gc->get_direction && gpiochip_line_is_valid(gc, desc_index)) + assign_bit(FLAG_IS_OUT, &desc->flags, + !gc->get_direction(gc, desc_index)); + else assign_bit(FLAG_IS_OUT, &desc->flags, !gc->direction_input); - } } =20 ret =3D of_gpiochip_add(gc); --=20 2.45.2