linux-kernel - [PATCH] leds-fsg: Change order of initialization and deinitialization

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Date:	Sun, 27 Jul 2008 20:30:59 +0200 (CEST)
From:	Sven Wegener <sven.wegener@...aler.net>
To:	Richard Purdie <rpurdie@...ys.net>
cc:	Rod Whitby <rod@...tby.id.au>, linux-kernel@...r.kernel.org
Subject: [PATCH] leds-fsg: Change order of initialization and
 deinitialization

On initialization, we first do the ioremap and then register the led devices.
On deinitialization, we do it in reverse order. This prevents someone calling
into the brightness_set functions with an invalid latch_address.

Signed-off-by: Sven Wegener <sven.wegener@...aler.net>
Cc: Rod Whitby <rod@...tby.id.au>
---
 drivers/leds/leds-fsg.c |   28 ++++++++++++++--------------
 1 files changed, 14 insertions(+), 14 deletions(-)

I do not own a FSG-3, but it's probably a single CPU device and the chance 
of hitting this race condition is unlikely, but we should do it right 
nontheless. Further looking at the code, we probably also need a lock to 
make changing latch_value fully atomic, but again it is unlikely to hit 
this.

diff --git a/drivers/leds/leds-fsg.c b/drivers/leds/leds-fsg.c
index a7421b8..a26fe36 100644
--- a/drivers/leds/leds-fsg.c
+++ b/drivers/leds/leds-fsg.c
@@ -161,6 +161,16 @@ static int fsg_led_probe(struct platform_device *pdev)
 {
 	int ret;
 
+	/* Map the LED chip select address space */
+	latch_address = (unsigned short *) ioremap(IXP4XX_EXP_BUS_BASE(2), 512);
+	if (!latch_address) {
+		ret = -ENOMEM;
+		goto failremap;
+	}
+
+	latch_value = 0xffff;
+	*latch_address = latch_value;
+
 	ret = led_classdev_register(&pdev->dev, &fsg_wlan_led);
 	if (ret < 0)
 		goto failwlan;
@@ -185,20 +195,8 @@ static int fsg_led_probe(struct platform_device *pdev)
 	if (ret < 0)
 		goto failring;
 
-	/* Map the LED chip select address space */
-	latch_address = (unsigned short *) ioremap(IXP4XX_EXP_BUS_BASE(2), 512);
-	if (!latch_address) {
-		ret = -ENOMEM;
-		goto failremap;
-	}
-
-	latch_value = 0xffff;
-	*latch_address = latch_value;
-
 	return ret;
 
- failremap:
-	led_classdev_unregister(&fsg_ring_led);
  failring:
 	led_classdev_unregister(&fsg_sync_led);
  failsync:
@@ -210,14 +208,14 @@ static int fsg_led_probe(struct platform_device *pdev)
  failwan:
 	led_classdev_unregister(&fsg_wlan_led);
  failwlan:
+	iounmap(latch_address);
+ failremap:
 
 	return ret;
 }
 
 static int fsg_led_remove(struct platform_device *pdev)
 {
-	iounmap(latch_address);
-
 	led_classdev_unregister(&fsg_wlan_led);
 	led_classdev_unregister(&fsg_wan_led);
 	led_classdev_unregister(&fsg_sata_led);
@@ -225,6 +223,8 @@ static int fsg_led_remove(struct platform_device *pdev)
 	led_classdev_unregister(&fsg_sync_led);
 	led_classdev_unregister(&fsg_ring_led);
 
+	iounmap(latch_address);
+
 	return 0;
 }
 
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