From 54d9acd7540995b06a47974e3d06da7f68df9d4a Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Mon, 4 May 2015 17:10:35 +0200 Subject: [PATCH] gpio: sysfs: release irq after class-device deregistration Make sure to release any irq only after the class device has been deregistered. This avoids a race between gpiod_unexport and edge_store, where an irq could be allocated just before the gpio class device is deregistered without relying on FLAG_EXPORT and the global sysfs lock. Note that there is no need to hold the sysfs lock when releasing the irq after the class device is gone as kernfs will prevent further attribute operations. Signed-off-by: Johan Hovold Reviewed-by: Alexandre Courbot Signed-off-by: Linus Walleij --- drivers/gpio/gpiolib-sysfs.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c index a78dabd4035b..e4b079eec9bc 100644 --- a/drivers/gpio/gpiolib-sysfs.c +++ b/drivers/gpio/gpiolib-sysfs.c @@ -695,7 +695,6 @@ void gpiod_unexport(struct gpio_desc *desc) dev = class_find_device(&gpio_class, NULL, desc, match_export); if (dev) { - gpio_setup_irq(desc, dev, 0); clear_bit(FLAG_SYSFS_DIR, &desc->flags); clear_bit(FLAG_EXPORT, &desc->flags); } else @@ -706,6 +705,11 @@ void gpiod_unexport(struct gpio_desc *desc) if (dev) { device_unregister(dev); + /* + * Release irq after deregistration to prevent race with + * edge_store. + */ + gpio_setup_irq(desc, dev, 0); put_device(dev); }