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From: Tzung-Bi Shih <tzungbi@kernel.org>
To: Bartosz Golaszewski <brgl@kernel.org>, Linus Walleij <linusw@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>,
	linux-kernel@vger.kernel.org, linux-gpio@vger.kernel.org,
	linux-kselftest@vger.kernel.org, tzungbi@kernel.org
Subject: [PATCH v4 5/6] gpio: cdev: Don't check struct gpio_chip in gpio_chrdev_open()
Date: Mon, 23 Feb 2026 14:17:25 +0800	[thread overview]
Message-ID: <20260223061726.82161-6-tzungbi@kernel.org> (raw)
In-Reply-To: <20260223061726.82161-1-tzungbi@kernel.org>

It's harmless even if: chrdev_open() and cdev_device_del() run at the
same time, and gpio_chrdev_open() gets called after the underlying GPIO
chip has gone.  The subsequent file operations check the availability
of struct gpio_chip anyway.

Don't check struct gpio_chip in gpio_chrdev_open().

Reviewed-by: Linus Walleij <linusw@kernel.org>
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
---
v4:
- Add R-b tag.

v3: https://lore.kernel.org/all/20260213092958.864411-6-tzungbi@kernel.org
- No changes.

v2: https://lore.kernel.org/all/20260203061059.975605-6-tzungbi@kernel.org
- No changes.

v1: https://lore.kernel.org/all/20260116081036.352286-11-tzungbi@kernel.org

 drivers/gpio/gpiolib-cdev.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index a154b04e9316..475ad185f915 100644
--- a/drivers/gpio/gpiolib-cdev.c
+++ b/drivers/gpio/gpiolib-cdev.c
@@ -2689,12 +2689,6 @@ static int gpio_chrdev_open(struct inode *inode, struct file *file)
 	struct gpio_chardev_data *cdev;
 	int ret = -ENOMEM;
 
-	guard(srcu)(&gdev->srcu);
-
-	/* Fail on open if the backing gpiochip is gone */
-	if (!rcu_access_pointer(gdev->chip))
-		return -ENODEV;
-
 	cdev = kzalloc(sizeof(*cdev), GFP_KERNEL);
 	if (!cdev)
 		return -ENOMEM;
-- 
2.51.0


  parent reply	other threads:[~2026-02-23  6:17 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-02-23  6:17 [PATCH v4 0/6] gpio: Refactor and add selftest Tzung-Bi Shih
2026-02-23  6:17 ` [PATCH v4 1/6] gpio: Access `gpio_bus_type` in gpiochip_setup_dev() Tzung-Bi Shih
2026-03-11 11:44   ` Geert Uytterhoeven
2026-03-11 14:36     ` Bartosz Golaszewski
2026-03-12  4:52       ` Tzung-Bi Shih
2026-02-23  6:17 ` [PATCH v4 2/6] gpio: Remove redundant check for struct gpio_chip Tzung-Bi Shih
2026-02-23  6:17 ` [PATCH v4 3/6] gpio: sysfs: " Tzung-Bi Shih
2026-02-23  6:17 ` [PATCH v4 4/6] gpio: Ensure struct gpio_chip for gpiochip_setup_dev() Tzung-Bi Shih
2026-02-27 21:36   ` Marek Szyprowski
2026-02-28 10:03     ` Bartosz Golaszewski
2026-02-28 13:20       ` Tzung-Bi Shih
2026-02-23  6:17 ` Tzung-Bi Shih [this message]
2026-02-23  6:17 ` [PATCH v4 6/6] selftests: gpio: Add gpio-cdev-uaf tests Tzung-Bi Shih
2026-02-25 10:26 ` [PATCH v4 0/6] gpio: Refactor and add selftest Bartosz Golaszewski
2026-02-26 12:44   ` Tzung-Bi Shih
2026-02-27  9:10     ` Bartosz Golaszewski
2026-02-27  9:08 ` Bartosz Golaszewski
2026-02-27  9:22 ` Linus Walleij

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