FAILED: patch "[PATCH] leds: triggers: Flush pending brightness before activating" failed to apply to 5.10-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y
git checkout FETCH_HEAD
git cherry-pick -x ab477b766edd3bfb6321a6e3df4c790612613fae
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2024072916-emphasize-gluten-2f10@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^..

Possible dependencies:

ab477b766edd ("leds: triggers: Flush pending brightness before activating trigger")
b1bbd20f35e1 ("leds: trigger: Call synchronize_rcu() before calling trig->activate()")
822c91e72eac ("leds: trigger: Store brightness set by led_trigger_event()")
c82a1662d454 ("leds: trigger: Remove unused function led_trigger_rename_static()")
2a5a8fa8b231 ("leds: trigger: use RCU to protect the led_cdevs list")
27af8e2c90fb ("leds: trigger: fix potential deadlock with libata")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From ab477b766edd3bfb6321a6e3df4c790612613fae Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thomas=20Wei=C3=9Fschuh?= <linux@weissschuh.net>
Date: Thu, 13 Jun 2024 17:24:51 +0200
Subject: [PATCH] leds: triggers: Flush pending brightness before activating
 trigger
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The race fixed in timer_trig_activate() between a blocking
set_brightness() call and trigger->activate() can affect any trigger.
So move the call to flush_work() into led_trigger_set() where it can
avoid the race for all triggers.

Fixes: 0db37915d912 ("leds: avoid races with workqueue")
Fixes: 8c0f693c6eff ("leds: avoid flush_work in atomic context")
Cc: stable@vger.kernel.org
Tested-by: Dustin L. Howett <dustin@howett.net>
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://lore.kernel.org/r/20240613-led-trigger-flush-v2-1-f4f970799d77@weissschuh.net
Signed-off-by: Lee Jones <lee@kernel.org>

diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c
index 59deadb86335..78eb20093b2c 100644
--- a/drivers/leds/led-triggers.c
+++ b/drivers/leds/led-triggers.c
@@ -201,6 +201,12 @@ int led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trig)
 		 */
 		synchronize_rcu();
 
+		/*
+		 * If "set brightness to 0" is pending in workqueue,
+		 * we don't want that to be reordered after ->activate()
+		 */
+		flush_work(&led_cdev->set_brightness_work);
+
 		ret = 0;
 		if (trig->activate)
 			ret = trig->activate(led_cdev);
diff --git a/drivers/leds/trigger/ledtrig-timer.c b/drivers/leds/trigger/ledtrig-timer.c
index b4688d1d9d2b..1d213c999d40 100644
--- a/drivers/leds/trigger/ledtrig-timer.c
+++ b/drivers/leds/trigger/ledtrig-timer.c
@@ -110,11 +110,6 @@ static int timer_trig_activate(struct led_classdev *led_cdev)
 		led_cdev->flags &= ~LED_INIT_DEFAULT_TRIGGER;
 	}
 
-	/*
-	 * If "set brightness to 0" is pending in workqueue, we don't
-	 * want that to be reordered after blink_set()
-	 */
-	flush_work(&led_cdev->set_brightness_work);
 	led_blink_set(led_cdev, &led_cdev->blink_delay_on,
 		      &led_cdev->blink_delay_off);