Hi Heiner, On 01/08/2016 09:31 PM, Heiner Kallweit wrote:
I'm a little puzzled about the more or less completely missing locking in the LED core. Let's just take led_timer_function as example. It modifies led_cdev->flags and led_cdev->brightness from soft irq context (soft blink timer) w/o locking. Accessing these fields is not guaranteed to be atomic and the function doesn't even use set_bit etc. for modifying the bitmap. And brightness_set and other exported functions can even be called from hard irq context (e.g. by triggers).
led_set_brightness() behaves differently when blink timer is enabled. This issue was initially addressed by the patch [1]. Currently even more related improvements sit on linux-next.
This seems to be quite unsafe to me. Just think of a soft or hard irq colliding with a sysfs access. IMHO it's just due to the fact that these collision scenarios are relatively unlikely that we don't have problems. Am I missing something or is this actually an open issue? -- To unsubscribe from this list: send the line "unsubscribe linux-leds" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
[1] http://www.spinics.net/lists/linux-leds/msg00006.html -- Best Regards, Jacek Anaszewski -- To unsubscribe from this list: send the line "unsubscribe linux-leds" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
