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Date:   Sun, 8 Sep 2019 14:10:34 +0100
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     Akinobu Mita <akinobu.mita@gmail.com>
Cc:     linux-leds@vger.kernel.org, linux-kernel@vger.kernel.org,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Jacek Anaszewski <jacek.anaszewski@gmail.com>,
        Pavel Machek <pavel@ucw.cz>, Dan Murphy <dmurphy@ti.com>
Subject: Re: [PATCH 1/5] leds: remove PAGE_SIZE limit of
 /sys/class/leds/<led>/trigger
Message-ID: <20190908131034.GD9466@kroah.com>
References: <1567946472-10075-1-git-send-email-akinobu.mita@gmail.com>
 <1567946472-10075-2-git-send-email-akinobu.mita@gmail.com>
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On Sun, Sep 08, 2019 at 09:41:08PM +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.
> 
> This converts /sys/class/leds/<led>/trigger to bin attribute and removes
> the PAGE_SIZE limitation.
> 
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: "Rafael J. Wysocki" <rafael@kernel.org>
> Cc: Jacek Anaszewski <jacek.anaszewski@gmail.com>
> Cc: Pavel Machek <pavel@ucw.cz>
> Cc: Dan Murphy <dmurphy@ti.com>
> Acked-by: Pavel Machek <pavel@ucw.cz>
> Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
> ---
>  drivers/leds/led-class.c    |  8 ++--
>  drivers/leds/led-triggers.c | 90 ++++++++++++++++++++++++++++++++++-----------
>  drivers/leds/leds.h         |  6 +++
>  include/linux/leds.h        |  5 ---
>  4 files changed, 79 insertions(+), 30 deletions(-)
> 
> diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
> index 4793e77..8b5a1d1 100644
> --- a/drivers/leds/led-class.c
> +++ b/drivers/leds/led-class.c
> @@ -73,13 +73,13 @@ static ssize_t max_brightness_show(struct device *dev,
>  static DEVICE_ATTR_RO(max_brightness);
>  
>  #ifdef CONFIG_LEDS_TRIGGERS
> -static DEVICE_ATTR(trigger, 0644, led_trigger_show, led_trigger_store);
> -static struct attribute *led_trigger_attrs[] = {
> -	&dev_attr_trigger.attr,
> +static BIN_ATTR(trigger, 0644, led_trigger_read, led_trigger_write, 0);

BIN_ATTR_RW()?