[PATCH] Switch leds from mutex to spinlock to work in atomic contexts

[Holger Freyther]

Hey,

cat /sys/class/leds/some-led/trigger will show you which triggers are 
available. echo "bat-charging" > trigger will enable the trigger for this 
led. Now doing this lead to a BUG call as mutex_lock will use might_sleep 
which is forbidden in atomic contexts. Switch from using a mutex to spinlock 
to control the brightnes of the leds...


this patch seems to work, mutex_destroy was replaced with nothing but that 
looks correct too.

z.

PS: The LED trigger for charging works but with a bigger delay... we might 
want to schedule something when usb was plugged as we know we are going to 
charge soon?

From 3a32be40f78404d5f1185f0b3d6b5632381cb33f Mon Sep 17 00:00:00 2001
From: Holger Freyther <[EMAIL PROTECTED]>
Date: Mon, 7 Jul 2008 10:32:21 +0200
Subject: [PATCH] [neo1973 leds] Move from mutex to spinlock because we may not use mutexes
    The led triggers may call set_brightness from atomic contexts. As
    mutex_lock calls might_sleep and sleeping is not allowed in atomic contexts
    we have to switch to spinlocks here.

Signed-Off-By: Holger Freyther <[EMAIL PROTECTED]>
---
 drivers/leds/leds-neo1973-gta02.c |   10 +++++-----
 1 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/leds/leds-neo1973-gta02.c b/drivers/leds/leds-neo1973-gta02.c
index 952ad69..7b03c48 100644
--- a/drivers/leds/leds-neo1973-gta02.c
+++ b/drivers/leds/leds-neo1973-gta02.c
@@ -27,7 +27,7 @@
 
 struct gta02_led_priv
 {
-	struct mutex mutex;
+	spinlock_t lock;
 	struct led_classdev cdev;
 	struct s3c2410_pwm pwm;
 	unsigned int gpio;
@@ -53,6 +53,7 @@ static inline struct gta02_led_bundle *to_bundle(struct led_classdev *led_cdev)
 static void gta02led_set(struct led_classdev *led_cdev,
 		enum led_brightness value)
 {
+	unsigned long flags;
 	struct gta02_led_priv *lp = to_priv(led_cdev);
 
 	/*
@@ -60,7 +61,7 @@ static void gta02led_set(struct led_classdev *led_cdev,
  	 * value == 128 -> 50% duty cycle (medium power)
  	 * value == 0 -> 0% duty cycle (zero power)
  	 */
- 	mutex_lock(&lp->mutex);
+ 	spin_lock_irqsave(&lp->lock, flags);
 
 	if (lp->has_pwm) {
 		s3c2410_pwm_duty_cycle(value, &lp->pwm);
@@ -68,7 +69,7 @@ static void gta02led_set(struct led_classdev *led_cdev,
 		neo1973_gpb_setpin(lp->gpio, value ? 1 : 0);
 	}
 
-	mutex_unlock(&lp->mutex);
+	spin_unlock_irqrestore(&lp->lock, flags);
 }
 
 #ifdef CONFIG_PM
@@ -170,7 +171,7 @@ static int __init gta02led_probe(struct platform_device *pdev)
 			break;
 		}
 
-		mutex_init(&lp->mutex);
+		spin_lock_init(&lp->lock);
 		rc = led_classdev_register(&pdev->dev, &lp->cdev);
 	}
 
@@ -192,7 +193,6 @@ static int gta02led_remove(struct platform_device *pdev)
 			gta02led_set(&lp->cdev, 0);
 
 		led_classdev_unregister(&lp->cdev);
-		mutex_destroy(&lp->mutex);
 	}
 
 	platform_set_drvdata(pdev, NULL);
-- 
1.5.2.3