linux-kernel - [PATCH] gpio: sysfs: repair export returning -EPERM on 1st attempt

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Date: Thu,  7 Mar 2024 22:43:16 +0100
From: Alexander Sverdlin <alexander.sverdlin@...il.com>
To: linux-gpio@...r.kernel.org
Cc: Alexander Sverdlin <alexander.sverdlin@...il.com>,
	Bartosz Golaszewski <brgl@...ev.pl>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH] gpio: sysfs: repair export returning -EPERM on 1st attempt

It would make sense to return -EPERM if the bit was already set (already
used), not if it was cleared. Before this fix pins can only be exported on
the 2nd attempt:

$ echo 522 > /sys/class/gpio/export 
sh: write error: Operation not permitted
$ echo 522 > /sys/class/gpio/export 

Fixes: 35b545332b80 ("gpio: remove gpio_lock")
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@...il.com>
---
 drivers/gpio/gpiolib-sysfs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index 67fc09a57f26..6853ecd98bcb 100644
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -593,7 +593,7 @@ int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
 	if (!guard.gc)
 		return -ENODEV;
 
-	if (!test_and_set_bit(FLAG_EXPORT, &desc->flags))
+	if (test_and_set_bit(FLAG_EXPORT, &desc->flags))
 		return -EPERM;
 
 	gdev = desc->gdev;
-- 
2.43.2