[PATCH 4.19 38/55] gpiolib: sysfs: Fix error handling on failed export - Greg Kroah-Hartman

From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	patches@lists.linux.dev,
	Boerge Struempfel <boerge.struempfel@gmail.com>,
	Andy Shevchenko <andy@kernel.org>,
	Bartosz Golaszewski <bartosz.golaszewski@linaro.org>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.19 38/55] gpiolib: sysfs: Fix error handling on failed export
Date: Mon, 11 Dec 2023 19:21:48 +0100	[thread overview]
Message-ID: <20231211182013.671484691@linuxfoundation.org> (raw)
In-Reply-To: <20231211182012.263036284@linuxfoundation.org>

4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Boerge Struempfel <boerge.struempfel@gmail.com>

[ Upstream commit 95dd1e34ff5bbee93a28ff3947eceaf6de811b1a ]

If gpio_set_transitory() fails, we should free the GPIO again. Most
notably, the flag FLAG_REQUESTED has previously been set in
gpiod_request_commit(), and should be reset on failure.

To my knowledge, this does not affect any current users, since the
gpio_set_transitory() mainly returns 0 and -ENOTSUPP, which is converted
to 0. However the gpio_set_transitory() function calles the .set_config()
function of the corresponding GPIO chip and there are some GPIO drivers in
which some (unlikely) branches return other values like -EPROBE_DEFER,
and -EINVAL. In these cases, the above mentioned FLAG_REQUESTED would not
be reset, which results in the pin being blocked until the next reboot.

Fixes: e10f72bf4b3e ("gpio: gpiolib: Generalise state persistence beyond sleep")
Signed-off-by: Boerge Struempfel <boerge.struempfel@gmail.com>
Reviewed-by: Andy Shevchenko <andy@kernel.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpio/gpiolib-sysfs.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index e0ccc79b239a5..7a8dfc36a6c15 100644
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -495,14 +495,17 @@ static ssize_t export_store(struct class *class,
 	}
 
 	status = gpiod_set_transitory(desc, false);
-	if (!status) {
-		status = gpiod_export(desc, true);
-		if (status < 0)
-			gpiod_free(desc);
-		else
-			set_bit(FLAG_SYSFS, &desc->flags);
+	if (status) {
+		gpiod_free(desc);
+		goto done;
 	}
 
+	status = gpiod_export(desc, true);
+	if (status < 0)
+		gpiod_free(desc);
+	else
+		set_bit(FLAG_SYSFS, &desc->flags);
+
 done:
 	if (status)
 		pr_debug("%s: status %d\n", __func__, status);
-- 
2.42.0



