Struct gpio_device now provides a revocable provider to the underlying struct gpio_chip. Leverage revocable for lineevent_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 | 46 ++++++++++++++++++++++++------------- 1 file changed, 30 insertions(+), 16 deletions(-) diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c index f078d135a581..54150d718931 100644 --- a/drivers/gpio/gpiolib-cdev.c +++ b/drivers/gpio/gpiolib-cdev.c @@ -1772,7 +1772,7 @@ static int linereq_create(struct gpio_device *gdev, void __user *ip) /** * struct lineevent_state - contains the state of a userspace event - * @gdev: the GPIO device the event pertains to + * @chip_rev: revocable consumer handle for the corresponding struct gpio_chip * @label: consumer label used to tag descriptors * @desc: the GPIO descriptor held by this event * @eflags: the event flags this line was requested with @@ -1785,7 +1785,7 @@ static int linereq_create(struct gpio_device *gdev, void __user *ip) * event */ struct lineevent_state { - struct gpio_device *gdev; + struct revocable *chip_rev; const char *label; struct gpio_desc *desc; u32 eflags; @@ -1805,10 +1805,10 @@ static __poll_t lineevent_poll(struct file *file, { struct lineevent_state *le = file->private_data; __poll_t events = 0; + struct gpio_chip *gc; - guard(srcu)(&le->gdev->srcu); - - if (!rcu_access_pointer(le->gdev->chip)) + REVOCABLE_TRY_ACCESS_WITH(le->chip_rev, gc); + if (!gc) return EPOLLHUP | EPOLLERR; poll_wait(file, &le->wait, wait); @@ -1843,10 +1843,10 @@ static ssize_t lineevent_read(struct file *file, char __user *buf, ssize_t bytes_read = 0; ssize_t ge_size; int ret; + struct gpio_chip *gc; - guard(srcu)(&le->gdev->srcu); - - if (!rcu_access_pointer(le->gdev->chip)) + REVOCABLE_TRY_ACCESS_WITH(le->chip_rev, gc); + if (!gc) return -ENODEV; /* @@ -1901,15 +1901,24 @@ static ssize_t lineevent_read(struct file *file, char __user *buf, static void lineevent_free(struct lineevent_state *le) { - if (le->device_unregistered_nb.notifier_call) - blocking_notifier_chain_unregister(&le->gdev->device_notifier, - &le->device_unregistered_nb); + if (le->device_unregistered_nb.notifier_call) { + struct gpio_chip *gc; + + REVOCABLE_TRY_ACCESS_WITH(le->chip_rev, gc); + if (gc) { + struct gpio_device *gdev = gc->gpiodev; + + blocking_notifier_chain_unregister(&gdev->device_notifier, + &le->device_unregistered_nb); + } + } if (le->irq) free_irq_label(free_irq(le->irq, le)); if (le->desc) gpiod_free(le->desc); kfree(le->label); - gpio_device_put(le->gdev); + if (le->chip_rev) + revocable_free(le->chip_rev); kfree(le); } @@ -1925,10 +1934,10 @@ static long lineevent_ioctl(struct file *file, unsigned int cmd, struct lineevent_state *le = file->private_data; void __user *ip = (void __user *)arg; struct gpiohandle_data ghd; + struct gpio_chip *gc; - guard(srcu)(&le->gdev->srcu); - - if (!rcu_access_pointer(le->gdev->chip)) + REVOCABLE_TRY_ACCESS_WITH(le->chip_rev, gc); + if (!gc) return -ENODEV; /* @@ -2081,7 +2090,12 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip) le = kzalloc(sizeof(*le), GFP_KERNEL); if (!le) return -ENOMEM; - le->gdev = gpio_device_get(gdev); + + le->chip_rev = revocable_alloc(gdev->chip_rp); + if (!le->chip_rev) { + ret = -ENOMEM; + goto out_free_le; + } if (eventreq.consumer_label[0] != '\0') { /* label is only initialized if consumer_label is set */ -- 2.52.0.457.g6b5491de43-goog
