Struct gpio_device now provides a revocable provider to the underlying struct gpio_chip. Leverage revocable for line_fileops so that it doesn't need to handle the synchronization by accessing the SRCU explicitly.
Also, it's unneeded to hold a reference count to the struct gpio_device while the file is opening. The struct gpio_device (i.e., (struct gpio_chip *)->gpiodev)) is valid as long as struct gpio_chip is valid. Signed-off-by: Tzung-Bi Shih <[email protected]> --- drivers/gpio/gpiolib-cdev.c | 53 +++++++++++++++++++++++++------------ 1 file changed, 36 insertions(+), 17 deletions(-) diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c index f7c6f1367235..f078d135a581 100644 --- a/drivers/gpio/gpiolib-cdev.c +++ b/drivers/gpio/gpiolib-cdev.c @@ -488,7 +488,7 @@ struct line { /** * struct linereq - contains the state of a userspace line request - * @gdev: the GPIO device the line request pertains to + * @chip_rev: revocable consumer handle for the corresponding struct gpio_chip * @label: consumer label used to tag GPIO descriptors * @num_lines: the number of lines in the lines array * @wait: wait queue that handles blocking reads of events @@ -503,7 +503,7 @@ struct line { * @lines: the lines held by this line request, with @num_lines elements. */ struct linereq { - struct gpio_device *gdev; + struct revocable *chip_rev; const char *label; u32 num_lines; wait_queue_head_t wait; @@ -1437,10 +1437,10 @@ static long linereq_ioctl(struct file *file, unsigned int cmd, { struct linereq *lr = file->private_data; void __user *ip = (void __user *)arg; + struct gpio_chip *gc; - guard(srcu)(&lr->gdev->srcu); - - if (!rcu_access_pointer(lr->gdev->chip)) + REVOCABLE_TRY_ACCESS_WITH(lr->chip_rev, gc); + if (!gc) return -ENODEV; switch (cmd) { @@ -1468,10 +1468,10 @@ static __poll_t linereq_poll(struct file *file, { struct linereq *lr = file->private_data; __poll_t events = 0; + struct gpio_chip *gc; - guard(srcu)(&lr->gdev->srcu); - - if (!rcu_access_pointer(lr->gdev->chip)) + REVOCABLE_TRY_ACCESS_WITH(lr->chip_rev, gc); + if (!gc) return EPOLLHUP | EPOLLERR; poll_wait(file, &lr->wait, wait); @@ -1490,10 +1490,10 @@ static ssize_t linereq_read(struct file *file, char __user *buf, struct gpio_v2_line_event le; ssize_t bytes_read = 0; int ret; + struct gpio_chip *gc; - guard(srcu)(&lr->gdev->srcu); - - if (!rcu_access_pointer(lr->gdev->chip)) + REVOCABLE_TRY_ACCESS_WITH(lr->chip_rev, gc); + if (!gc) return -ENODEV; if (count < sizeof(le)) @@ -1537,9 +1537,17 @@ static void linereq_free(struct linereq *lr) { unsigned int i; - if (lr->device_unregistered_nb.notifier_call) - blocking_notifier_chain_unregister(&lr->gdev->device_notifier, - &lr->device_unregistered_nb); + if (lr->device_unregistered_nb.notifier_call) { + struct gpio_chip *gc; + + REVOCABLE_TRY_ACCESS_WITH(lr->chip_rev, gc); + if (gc) { + struct gpio_device *gdev = gc->gpiodev; + + blocking_notifier_chain_unregister(&gdev->device_notifier, + &lr->device_unregistered_nb); + } + } for (i = 0; i < lr->num_lines; i++) { if (lr->lines[i].desc) { @@ -1549,7 +1557,8 @@ static void linereq_free(struct linereq *lr) } kfifo_free(&lr->events); kfree(lr->label); - gpio_device_put(lr->gdev); + if (lr->chip_rev) + revocable_free(lr->chip_rev); kvfree(lr); } @@ -1565,9 +1574,15 @@ static int linereq_release(struct inode *inode, struct file *file) static void linereq_show_fdinfo(struct seq_file *out, struct file *file) { struct linereq *lr = file->private_data; - struct device *dev = &lr->gdev->dev; + struct gpio_chip *gc; + struct device *dev; u16 i; + REVOCABLE_TRY_ACCESS_WITH(lr->chip_rev, gc); + if (!gc) + return; + dev = &gc->gpiodev->dev; + seq_printf(out, "gpio-chip:\t%s\n", dev_name(dev)); for (i = 0; i < lr->num_lines; i++) @@ -1620,7 +1635,11 @@ static int linereq_create(struct gpio_device *gdev, void __user *ip) return -ENOMEM; lr->num_lines = ulr.num_lines; - lr->gdev = gpio_device_get(gdev); + lr->chip_rev = revocable_alloc(gdev->chip_rp); + if (!lr->chip_rev) { + ret = -ENOMEM; + goto out_free_linereq; + } for (i = 0; i < ulr.num_lines; i++) { lr->lines[i].req = lr; -- 2.52.0.457.g6b5491de43-goog
