From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hans de Goede Subject: [PATCH 2/2] led: core: Fix blink_brightness setting race Date: Sun, 23 Oct 2016 21:47:26 +0200 Message-ID: <20161023194726.24388-2-hdegoede@redhat.com> References: <20161023194726.24388-1-hdegoede@redhat.com> Return-path: Received: from mx1.redhat.com ([209.132.183.28]:41740 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753493AbcJWTrc (ORCPT ); Sun, 23 Oct 2016 15:47:32 -0400 In-Reply-To: <20161023194726.24388-1-hdegoede@redhat.com> Sender: linux-leds-owner@vger.kernel.org List-Id: linux-leds@vger.kernel.org To: Richard Purdie , Jacek Anaszewski Cc: linux-leds@vger.kernel.org, Hans de Goede All 3 of led_timer_func, led_set_brightness and led_set_software_blink set blink_brightness. If led_timer_func or led_set_software_blink race with led_set_brightness they may end up overwriting the new blink_brightness. The new atomic work_flags does not protect against this as it just protects the flags and not blink_brightness. This commit introduces a new new_blink_brightness value which gets set by led_set_brightness and read by led_timer_func on LED on, fixing this. Dealing with the new brightness at LED on time, makes the new brightness apply sooner, which also fixes a led_set_brightness which happens while a oneshot blink which ends in LED on is running not getting applied. Signed-off-by: Hans de Goede --- drivers/leds/led-core.c | 14 +++++++------- include/linux/leds.h | 1 + 2 files changed, 8 insertions(+), 7 deletions(-) diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c index 17a0964..d474f97 100644 --- a/drivers/leds/led-core.c +++ b/drivers/leds/led-core.c @@ -81,17 +81,17 @@ static void led_timer_function(unsigned long data) brightness = led_get_brightness(led_cdev); if (!brightness) { /* Time to switch the LED on. */ - brightness = led_cdev->blink_brightness; + if (test_and_clear_bit(LED_BLINK_BRIGHTNESS_CHANGE, + &led_cdev->work_flags)) + brightness = led_cdev->new_blink_brightness; + else + brightness = led_cdev->blink_brightness; delay = led_cdev->blink_delay_on; } else { /* Store the current brightness value to be able * to restore it when the delay_off period is over. - * Do it only if there is no pending blink brightness - * change, to avoid overwriting the new value. */ - if (!test_and_clear_bit(LED_BLINK_BRIGHTNESS_CHANGE, - &led_cdev->work_flags)) - led_cdev->blink_brightness = brightness; + led_cdev->blink_brightness = brightness; brightness = LED_OFF; delay = led_cdev->blink_delay_off; } @@ -260,7 +260,7 @@ void led_set_brightness(struct led_classdev *led_cdev, } else { set_bit(LED_BLINK_BRIGHTNESS_CHANGE, &led_cdev->work_flags); - led_cdev->blink_brightness = brightness; + led_cdev->new_blink_brightness = brightness; } return; } diff --git a/include/linux/leds.h b/include/linux/leds.h index cff9df7..6669404 100644 --- a/include/linux/leds.h +++ b/include/linux/leds.h @@ -87,6 +87,7 @@ struct led_classdev { unsigned long blink_delay_on, blink_delay_off; struct timer_list blink_timer; int blink_brightness; + int new_blink_brightness; void (*flash_resume)(struct led_classdev *led_cdev); struct work_struct set_brightness_work; -- 2.9.3