Re: [PATCH v3 1/1] leds: remove PAGE_SIZE limit of /sys/class/leds/<led>/trigger

From: Greg Kroah-Hartman
Date: Mon Sep 30 2019 - 10:08:11 EST


On Sun, Sep 29, 2019 at 11:18:49PM +0900, Akinobu Mita wrote:
> Reading /sys/class/leds/<led>/trigger returns all available LED triggers.
> However, the size of this file is limited to PAGE_SIZE because of the
> limitation for sysfs attribute.
>
> Enabling LED CPU trigger on systems with thousands of CPUs easily hits
> PAGE_SIZE limit, and makes it impossible to see all available LED triggers
> and which trigger is currently activated.
>
> We work around it here by converting /sys/class/leds/<led>/trigger to
> binary attribute, which is not limited by length. This is _not_ good
> design, do not copy it.
>
> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx>
> Cc: Jacek Anaszewski <jacek.anaszewski@xxxxxxxxx>
> Cc: Pavel Machek <pavel@xxxxxx>
> Cc: Dan Murphy <dmurphy@xxxxxx>
> Signed-off-by: Akinobu Mita <akinobu.mita@xxxxxxxxx>

Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>