Re: [PATCH] leds: Add mutex protection in brightness_show()

[Jacek Anaszewski]

Hi,

On 11/09/2016 01:38 PM, Pavel Machek wrote:
> Hi!
>
> > Initially the claim about no need for lock in brightness_show()
> > was valid as the function was just returning unchanged
> > LED brightness. After the addition of led_update_brightness() this
>
> The claim was probably wrong from the day one, unless brightness is of
> type "atomic_t".
>
>              /* Ensures consistent access to the LED Flash Class device */
> 	        struct mutex            led_access;
> 		};
>
> This should really list fields that are protected by led_access.

Originally it was introduced to facilitate disabling LED subsystem
sysfs interface, i.e. it protects flags property of
struct led_classdev.

--
Best regards,
Jacek Anaszewski