From 97b31c1f8eb865bc3aa5f4a08286a6406d782ea8 Mon Sep 17 00:00:00 2001
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Wed, 13 Oct 2021 11:37:19 +0200
Subject: [PATCH] leds: trigger: Disable CPU trigger on PREEMPT_RT
Git-commit: 97b31c1f8eb865bc3aa5f4a08286a6406d782ea8
Patch-mainline: v5.15-rc1
References: bsc#1189998

The CPU trigger is invoked on ARM from CPU-idle. That trigger later
invokes led_trigger_event() which may invoke the callback of the actual driver.
That driver can acquire a spinlock_t which is okay on kernel without
PREEMPT_RT. On a PREEMPT_RT enabled kernel this lock is turned into a
sleeping lock and must not be acquired with disabled interrupts.

Disable the CPU trigger on PREEMPT_RT.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lkml.kernel.org/r/20210924111501.m57cwwn7ahiyxxdd@linutronix.de
Signed-off-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>

---
 drivers/leds/trigger/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/leds/trigger/Kconfig b/drivers/leds/trigger/Kconfig
index 1f1d57288085..dc6816d36d06 100644
--- a/drivers/leds/trigger/Kconfig
+++ b/drivers/leds/trigger/Kconfig
@@ -64,6 +64,7 @@ config LEDS_TRIGGER_BACKLIGHT
 
 config LEDS_TRIGGER_CPU
 	bool "LED CPU Trigger"
+	depends on !PREEMPT_RT
 	help
 	  This allows LEDs to be controlled by active CPUs. This shows
 	  the active CPUs across an array of LEDs so you can see which
-- 
2.26.2