Re: [PATCH 20/22] gpio: protect the pointer to gpio_chip in gpio_device with SRCU

[Bartosz Golaszewski <brgl@xxxxxxxx>]

On Wed, 31 Jan 2024 01:41:11 +0100, kernel test robot <lkp@xxxxxxxxx> said:
> Hi Bartosz,
>
> kernel test robot noticed the following build errors:
>
> [auto build test ERROR on brgl/gpio/for-next]
> [also build test ERROR on linus/master v6.8-rc2 next-20240130]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch#_base_tree_information]
>
> url:    https://github.com/intel-lab-lkp/linux/commits/Bartosz-Golaszewski/gpio-protect-the-list-of-GPIO-devices-with-SRCU/20240130-205537
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux.git gpio/for-next
> patch link:    https://lore.kernel.org/r/20240130124828.14678-21-brgl%40bgdev.pl
> patch subject: [PATCH 20/22] gpio: protect the pointer to gpio_chip in gpio_device with SRCU
> config: x86_64-buildonly-randconfig-004-20240131 (https://download.01.org/0day-ci/archive/20240131/202401310855.aA6wzlm2-lkp@xxxxxxxxx/config)
> compiler: clang version 17.0.6 (https://github.com/llvm/llvm-project 6009708b4367171ccdbf4b5905cb6a803753fe18)
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240131/202401310855.aA6wzlm2-lkp@xxxxxxxxx/reproduce)
>
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@xxxxxxxxx>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202401310855.aA6wzlm2-lkp@xxxxxxxxx/
>
> All errors (new ones prefixed by >>):
>
>>> drivers/gpio/gpiolib-sysfs.c:481:3: error: cannot jump from this goto statement to its label
>      481 |                 goto done;
>          |                 ^
>    drivers/gpio/gpiolib-sysfs.c:490:25: note: jump bypasses initialization of variable with __attribute__((cleanup))
>      490 |         CLASS(gpio_chip_guard, guard)(desc);
>          |                                ^
>    1 error generated.
>

I fixed it up like this:

diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index c45b71adff2c..6a421309319e 100644
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -477,8 +477,8 @@ static ssize_t export_store(const struct class *class,
 	long gpio;

 	status = kstrtol(buf, 0, &gpio);
-	if (status < 0)
-		goto done;
+	if (status)
+		return status;

 	desc = gpio_to_desc(gpio);
 	/* reject invalid GPIOs */

There's no reason to jump to done here only to print the error code.

Bart

>
> vim +481 drivers/gpio/gpiolib-sysfs.c
>
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  464
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  465  /*
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  466   * /sys/class/gpio/export ... write-only
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  467   *	integer N ... number of GPIO to export (full access)
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  468   * /sys/class/gpio/unexport ... write-only
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  469   *	integer N ... number of GPIO to unexport
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  470   */
> 75a2d4226b5371 Greg Kroah-Hartman  2023-03-25  471  static ssize_t export_store(const struct class *class,
> 75a2d4226b5371 Greg Kroah-Hartman  2023-03-25  472  				const struct class_attribute *attr,
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  473  				const char *buf, size_t len)
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  474  {
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  475  	struct gpio_desc *desc;
> 513246a34b8dc5 Bartosz Golaszewski 2023-12-21  476  	int status, offset;
> 513246a34b8dc5 Bartosz Golaszewski 2023-12-21  477  	long gpio;
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  478
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  479  	status = kstrtol(buf, 0, &gpio);
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  480  	if (status < 0)
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01 @481  		goto done;
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  482
> f13a0b0bb46f07 Linus Walleij       2018-09-13  483  	desc = gpio_to_desc(gpio);
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  484  	/* reject invalid GPIOs */
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  485  	if (!desc) {
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  486  		pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  487  		return -EINVAL;
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  488  	}
> 2796d5332f8ac8 Bartosz Golaszewski 2024-01-30  489
> 2796d5332f8ac8 Bartosz Golaszewski 2024-01-30  490  	CLASS(gpio_chip_guard, guard)(desc);
> 2796d5332f8ac8 Bartosz Golaszewski 2024-01-30  491  	if (!guard.gc)
> 2796d5332f8ac8 Bartosz Golaszewski 2024-01-30  492  		return -ENODEV;
> 2796d5332f8ac8 Bartosz Golaszewski 2024-01-30  493
> 23cf00ddd2e1aa Matti Vaittinen     2021-03-29  494  	offset = gpio_chip_hwgpio(desc);
> 2796d5332f8ac8 Bartosz Golaszewski 2024-01-30  495  	if (!gpiochip_line_is_valid(guard.gc, offset)) {
> 23cf00ddd2e1aa Matti Vaittinen     2021-03-29  496  		pr_warn("%s: GPIO %ld masked\n", __func__, gpio);
> 23cf00ddd2e1aa Matti Vaittinen     2021-03-29  497  		return -EINVAL;
> 23cf00ddd2e1aa Matti Vaittinen     2021-03-29  498  	}
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  499
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  500  	/* No extra locking here; FLAG_SYSFS just signifies that the
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  501  	 * request and export were done by on behalf of userspace, so
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  502  	 * they may be undone on its behalf too.
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  503  	 */
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  504
> 95a4eed7dd5b7c Andy Shevchenko     2022-02-01  505  	status = gpiod_request_user(desc, "sysfs");
> 95a4eed7dd5b7c Andy Shevchenko     2022-02-01  506  	if (status)
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  507  		goto done;
> e10f72bf4b3e88 Andrew Jeffery      2017-11-30  508
> e10f72bf4b3e88 Andrew Jeffery      2017-11-30  509  	status = gpiod_set_transitory(desc, false);
> 95dd1e34ff5bbe Boerge Struempfel   2023-11-29  510  	if (status) {
> 95dd1e34ff5bbe Boerge Struempfel   2023-11-29  511  		gpiod_free(desc);
> 95dd1e34ff5bbe Boerge Struempfel   2023-11-29  512  		goto done;
> 95dd1e34ff5bbe Boerge Struempfel   2023-11-29  513  	}
> 95dd1e34ff5bbe Boerge Struempfel   2023-11-29  514
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  515  	status = gpiod_export(desc, true);
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  516  	if (status < 0)
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  517  		gpiod_free(desc);
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  518  	else
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  519  		set_bit(FLAG_SYSFS, &desc->flags);
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  520
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  521  done:
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  522  	if (status)
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  523  		pr_debug("%s: status %d\n", __func__, status);
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  524  	return status ? : len;
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  525  }
> d83bb159f4c6af Greg Kroah-Hartman  2017-06-08  526  static CLASS_ATTR_WO(export);
> 0eb4c6c2671ca0 Alexandre Courbot   2014-07-01  527
>
> --
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