[3.11.y.z extended stable] Patch "leds: leds-pwm: properly clean up after probe failure" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    leds: leds-pwm: properly clean up after probe failure

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 60607a0e6f086d16c4eccbae4a8fcfa016f8d93d Mon Sep 17 00:00:00 2001
From: Russell King <rmk+kernel at arm.linux.org.uk>
Date: Sun, 6 Apr 2014 15:20:03 -0700
Subject: leds: leds-pwm: properly clean up after probe failure

commit 392369019eb96e914234ea21eda806cb51a1073e upstream.

When probing with DT, we add each LED one at a time.  If we find a LED
without a PWM device (because it is not available yet) we fail the
initialisation, unregister previous LEDs, and then by way of managed
resources, we free the structure.

The problem with this is we may have a scheduled and active work_struct
in this structure, and this results in a nasty kernel oops.

We need to cancel this work_struct properly upon cleanup - and the
cleanup we require is the same cleanup as we do when the LED platform
device is removed.  Rather than writing this same code three times,
move it into a separate function and use it in all three places.

Fixes: c971ff185f64 ("leds: leds-pwm: Defer led_pwm_set() if PWM can sleep")
Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>
Signed-off-by: Bryan Wu <cooloney at gmail.com>
[ luis: backported to 3.11: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/leds/leds-pwm.c | 23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/drivers/leds/leds-pwm.c b/drivers/leds/leds-pwm.c
index faf52c005e8c..5d64b2431415 100644
--- a/drivers/leds/leds-pwm.c
+++ b/drivers/leds/leds-pwm.c
@@ -82,6 +82,15 @@ static inline size_t sizeof_pwm_leds_priv(int num_leds)
 		      (sizeof(struct led_pwm_data) * num_leds);
 }

+static void led_pwm_cleanup(struct led_pwm_priv *priv)
+{
+	while (priv->num_leds--) {
+		led_classdev_unregister(&priv->leds[priv->num_leds].cdev);
+		if (priv->leds[priv->num_leds].can_sleep)
+			cancel_work_sync(&priv->leds[priv->num_leds].work);
+	}
+}
+
 static struct led_pwm_priv *led_pwm_create_of(struct platform_device *pdev)
 {
 	struct device_node *node = pdev->dev.of_node;
@@ -139,8 +148,7 @@ static struct led_pwm_priv *led_pwm_create_of(struct platform_device *pdev)

 	return priv;
 err:
-	while (priv->num_leds--)
-		led_classdev_unregister(&priv->leds[priv->num_leds].cdev);
+	led_pwm_cleanup(priv);

 	return NULL;
 }
@@ -200,8 +208,8 @@ static int led_pwm_probe(struct platform_device *pdev)
 	return 0;

 err:
-	while (i--)
-		led_classdev_unregister(&priv->leds[i].cdev);
+	priv->num_leds = i;
+	led_pwm_cleanup(priv);

 	return ret;
 }
@@ -209,13 +217,8 @@ err:
 static int led_pwm_remove(struct platform_device *pdev)
 {
 	struct led_pwm_priv *priv = platform_get_drvdata(pdev);
-	int i;

-	for (i = 0; i < priv->num_leds; i++) {
-		led_classdev_unregister(&priv->leds[i].cdev);
-		if (priv->leds[i].can_sleep)
-			cancel_work_sync(&priv->leds[i].work);
-	}
+	led_pwm_cleanup(priv);

 	return 0;
 }
--
1.9.1