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McKenney" , Andy Shevchenko , Wolfram Sang Cc: linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org, Bartosz Golaszewski , kernel test robot Subject: [PATCH 2/3] gpio: cdev: use correct pointer accessors with SRCU Date: Tue, 13 Feb 2024 10:31:07 +0100 Message-Id: <20240213093108.13922-3-brgl@bgdev.pl> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20240213093108.13922-1-brgl@bgdev.pl> References: <20240213093108.13922-1-brgl@bgdev.pl> Precedence: bulk X-Mailing-List: linux-gpio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Bartosz Golaszewski We never dereference the chip pointer in character device code so we can use the lighter rcu_access_pointer() helper. This also makes lockep happier as it no longer complains about suspicious rcu_dereference() usage. Fixes: d83cee3d2bb1 ("gpio: protect the pointer to gpio_chip in gpio_device with SRCU") Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-lkp/202402122234.d85cca9b-lkp@intel.com Signed-off-by: Bartosz Golaszewski --- drivers/gpio/gpiolib-cdev.c | 25 ++++++++++++------------- 1 file changed, 12 insertions(+), 13 deletions(-) diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c index 9323b357df43..85037fa4925e 100644 --- a/drivers/gpio/gpiolib-cdev.c +++ b/drivers/gpio/gpiolib-cdev.c @@ -206,7 +206,7 @@ static long linehandle_ioctl(struct file *file, unsigned int cmd, guard(srcu)(&lh->gdev->srcu); - if (!rcu_dereference(lh->gdev->chip)) + if (!rcu_access_pointer(lh->gdev->chip)) return -ENODEV; switch (cmd) { @@ -1521,7 +1521,7 @@ static long linereq_ioctl(struct file *file, unsigned int cmd, guard(srcu)(&lr->gdev->srcu); - if (!rcu_dereference(lr->gdev->chip)) + if (!rcu_access_pointer(lr->gdev->chip)) return -ENODEV; switch (cmd) { @@ -1552,7 +1552,7 @@ static __poll_t linereq_poll(struct file *file, guard(srcu)(&lr->gdev->srcu); - if (!rcu_dereference(lr->gdev->chip)) + if (!rcu_access_pointer(lr->gdev->chip)) return EPOLLHUP | EPOLLERR; poll_wait(file, &lr->wait, wait); @@ -1574,7 +1574,7 @@ static ssize_t linereq_read(struct file *file, char __user *buf, guard(srcu)(&lr->gdev->srcu); - if (!rcu_dereference(lr->gdev->chip)) + if (!rcu_access_pointer(lr->gdev->chip)) return -ENODEV; if (count < sizeof(le)) @@ -1875,7 +1875,7 @@ static __poll_t lineevent_poll(struct file *file, guard(srcu)(&le->gdev->srcu); - if (!rcu_dereference(le->gdev->chip)) + if (!rcu_access_pointer(le->gdev->chip)) return EPOLLHUP | EPOLLERR; poll_wait(file, &le->wait, wait); @@ -1913,7 +1913,7 @@ static ssize_t lineevent_read(struct file *file, char __user *buf, guard(srcu)(&le->gdev->srcu); - if (!rcu_dereference(le->gdev->chip)) + if (!rcu_access_pointer(le->gdev->chip)) return -ENODEV; /* @@ -1996,7 +1996,7 @@ static long lineevent_ioctl(struct file *file, unsigned int cmd, guard(srcu)(&le->gdev->srcu); - if (!rcu_dereference(le->gdev->chip)) + if (!rcu_access_pointer(le->gdev->chip)) return -ENODEV; /* @@ -2510,7 +2510,7 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg) guard(srcu)(&gdev->srcu); /* We fail any subsequent ioctl():s when the chip is gone */ - if (!rcu_dereference(gdev->chip)) + if (!rcu_access_pointer(gdev->chip)) return -ENODEV; /* Fill in the struct and pass to userspace */ @@ -2595,7 +2595,7 @@ static __poll_t lineinfo_watch_poll(struct file *file, guard(srcu)(&cdev->gdev->srcu); - if (!rcu_dereference(cdev->gdev->chip)) + if (!rcu_access_pointer(cdev->gdev->chip)) return EPOLLHUP | EPOLLERR; poll_wait(file, &cdev->wait, pollt); @@ -2618,7 +2618,7 @@ static ssize_t lineinfo_watch_read(struct file *file, char __user *buf, guard(srcu)(&cdev->gdev->srcu); - if (!rcu_dereference(cdev->gdev->chip)) + if (!rcu_access_pointer(cdev->gdev->chip)) return -ENODEV; #ifndef CONFIG_GPIO_CDEV_V1 @@ -2696,7 +2696,7 @@ static int gpio_chrdev_open(struct inode *inode, struct file *file) guard(srcu)(&gdev->srcu); /* Fail on open if the backing gpiochip is gone */ - if (!rcu_dereference(gdev->chip)) + if (!rcu_access_pointer(gdev->chip)) return -ENODEV; cdev = kzalloc(sizeof(*cdev), GFP_KERNEL); @@ -2796,8 +2796,7 @@ int gpiolib_cdev_register(struct gpio_device *gdev, dev_t devt) guard(srcu)(&gdev->srcu); - gc = rcu_dereference(gdev->chip); - if (!gc) + if (!rcu_access_pointer(gdev->chip)) return -ENODEV; chip_dbg(gc, "added GPIO chardev (%d:%d)\n", MAJOR(devt), gdev->id);