Subject: [PATCH] leds: trigger: Disable CPU trigger on PREEMPT_RT
From: Sebastian Andrzej Siewior <[email-masked]>
Date: Thu, 23 Jan 2014 14:45:59 +0100

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 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 <[email-masked]>
Link: https://lkml.kernel.org/r/[email-masked]
---
 drivers/leds/trigger/Kconfig |    1 +
 1 file changed, 1 insertion(+)

--- 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