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McKenney" , Andy Shevchenko , Wolfram Sang Cc: lkp@intel.com, oe-kbuild-all@lists.linux.dev, linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org, Bartosz Golaszewski Subject: Re: [PATCH 20/22] gpio: protect the pointer to gpio_chip in gpio_device with SRCU Message-ID: <3ab71aad-757f-4d5e-ac09-fdad75238fa3@moroto.mountain> 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=us-ascii Content-Disposition: inline In-Reply-To: <20240130124828.14678-21-brgl@bgdev.pl> Hi Bartosz, kernel test robot noticed the following build warnings: 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: i386-randconfig-141-20240131 (https://download.01.org/0day-ci/archive/20240201/202402010641.idtEaO24-lkp@intel.com/config) compiler: clang version 17.0.6 (https://github.com/llvm/llvm-project 6009708b4367171ccdbf4b5905cb6a803753fe18) 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 | Reported-by: Dan Carpenter | Closes: https://lore.kernel.org/r/202402010641.idtEaO24-lkp@intel.com/ New smatch warnings: drivers/gpio/gpiolib.c:4776 gpiolib_dbg_show() error: we previously assumed 'gc' could be null (see line 4773) vim +/gc +4776 drivers/gpio/gpiolib.c fdeb8e1547cb9d Linus Walleij 2016-02-10 4762 static void gpiolib_dbg_show(struct seq_file *s, struct gpio_device *gdev) d2876d08d86f22 David Brownell 2008-02-04 4763 { 0338f6a6fb659f Bartosz Golaszewski 2023-12-21 4764 bool active_low, is_irq, is_out; 0338f6a6fb659f Bartosz Golaszewski 2023-12-21 4765 unsigned int gpio = gdev->base; 3de69ae1c407da Andy Shevchenko 2022-04-08 4766 struct gpio_desc *desc; 2796d5332f8ac8 Bartosz Golaszewski 2024-01-30 4767 struct gpio_chip *gc; 3de69ae1c407da Andy Shevchenko 2022-04-08 4768 int value; d2876d08d86f22 David Brownell 2008-02-04 4769 2796d5332f8ac8 Bartosz Golaszewski 2024-01-30 4770 guard(srcu)(&gdev->srcu); 2796d5332f8ac8 Bartosz Golaszewski 2024-01-30 4771 2796d5332f8ac8 Bartosz Golaszewski 2024-01-30 4772 gc = rcu_dereference(gdev->chip); 2796d5332f8ac8 Bartosz Golaszewski 2024-01-30 @4773 if (!gc) ^^^ The patch adds a NULL check 2796d5332f8ac8 Bartosz Golaszewski 2024-01-30 4774 seq_puts(s, "Underlying GPIO chip is gone\n"); 2796d5332f8ac8 Bartosz Golaszewski 2024-01-30 4775 3de69ae1c407da Andy Shevchenko 2022-04-08 @4776 for_each_gpio_desc(gc, desc) { ^^ But this dereference isn't checked... Probably it should return after the seq_puts(). bedc56b1695b27 Bartosz Golaszewski 2024-01-30 4777 guard(srcu)(&desc->srcu); 3de69ae1c407da Andy Shevchenko 2022-04-08 4778 if (test_bit(FLAG_REQUESTED, &desc->flags)) { 3de69ae1c407da Andy Shevchenko 2022-04-08 4779 gpiod_get_direction(desc); 3de69ae1c407da Andy Shevchenko 2022-04-08 4780 is_out = test_bit(FLAG_IS_OUT, &desc->flags); 234c52097ce416 Andy Shevchenko 2022-04-08 4781 value = gpio_chip_get_value(gc, desc); 3de69ae1c407da Andy Shevchenko 2022-04-08 4782 is_irq = test_bit(FLAG_USED_AS_IRQ, &desc->flags); 3de69ae1c407da Andy Shevchenko 2022-04-08 4783 active_low = test_bit(FLAG_ACTIVE_LOW, &desc->flags); 3de69ae1c407da Andy Shevchenko 2022-04-08 4784 seq_printf(s, " gpio-%-3d (%-20.20s|%-20.20s) %s %s %s%s\n", 32648f473c7f46 Bartosz Golaszewski 2024-01-30 4785 gpio, desc->name ?: "", gpiod_get_label(desc), d2876d08d86f22 David Brownell 2008-02-04 4786 is_out ? "out" : "in ", 3de69ae1c407da Andy Shevchenko 2022-04-08 4787 value >= 0 ? (value ? "hi" : "lo") : "? ", 90fd227029a25b Linus Walleij 2018-10-01 4788 is_irq ? "IRQ " : "", 90fd227029a25b Linus Walleij 2018-10-01 4789 active_low ? "ACTIVE LOW" : ""); 3de69ae1c407da Andy Shevchenko 2022-04-08 4790 } else if (desc->name) { 3de69ae1c407da Andy Shevchenko 2022-04-08 4791 seq_printf(s, " gpio-%-3d (%-20.20s)\n", gpio, desc->name); 3de69ae1c407da Andy Shevchenko 2022-04-08 4792 } 3de69ae1c407da Andy Shevchenko 2022-04-08 4793 3de69ae1c407da Andy Shevchenko 2022-04-08 4794 gpio++; d2876d08d86f22 David Brownell 2008-02-04 4795 } d2876d08d86f22 David Brownell 2008-02-04 4796 } -- 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests/wiki