linux-kernel - [PATCH] cris: fix locking in pcf8563.c

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Date:	Wed, 9 Mar 2011 12:55:28 +0100
From:	Arnd Bergmann <arnd@...db.de>
To:	Michael Brumlow <mbrumlow@...il.com>
Cc:	tobiasa@...s.com, linux-kernel@...r.kernel.org
Subject: [PATCH] cris: fix locking in pcf8563.c

The ioctl function was incorrectly converted to unlocked_ioctl,
this fixes the locking.

Reported-by: Michael Brumlow <mbrumlow@...il.com>
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
On Wednesday 09 March 2011, Michael Brumlow wrote:

> I was looking through some code and found an issue in the driver you
> wrote. The problem can be found in
> "arch/cris/arch-v10/drivers/pcf8563.c" function
> "pcf8563_unlocked_ioctl". The function locks a mutex and returns, when
> it should be locking the locking the mutex, storing the return from
> the function called and then unlocking the mutex and finally returning
> the stored value of the function called.
> 
> # in its current state.
>  343 static long pcf8563_unlocked_ioctl(struct file *filp, unsigned
> int cmd, unsigned long arg)
>  344 {
>  345         int ret;
>  346
>  347         mutex_lock(&pcf8563_mutex);
>  348         return pcf8563_ioctl(filp, cmd, arg);
>  349         mutex_unlock(&pcf8563_mutex);
>  350
>  351         return ret;
>  352 }
> 
> # what is suggested.
>  343 static long pcf8563_unlocked_ioctl(struct file *filp, unsigned
> int cmd, unsigned long arg)
>  344 {
>  345         int ret;
>  346
>  347         mutex_lock(&pcf8563_mutex);
>  348         ret = pcf8563_ioctl(filp, cmd, arg);
>  349         mutex_unlock(&pcf8563_mutex);
>  350
>  351         return ret;
>  352 }

You are right. This problem exists in both arch/cris/arch-v10/drivers/pcf8563.c
and arch/cris/arch-v32/drivers/pcf8563.c, and apparently both are my fault.

	Arnd
---
diff --git a/arch/cris/arch-v10/drivers/pcf8563.c b/arch/cris/arch-v10/drivers/pcf8563.c
index ea69fab..1391b73 100644
--- a/arch/cris/arch-v10/drivers/pcf8563.c
+++ b/arch/cris/arch-v10/drivers/pcf8563.c
@@ -345,7 +345,7 @@ static long pcf8563_unlocked_ioctl(struct file *filp, unsigned int cmd, unsigned
 	int ret;
 
 	mutex_lock(&pcf8563_mutex);
-	return pcf8563_ioctl(filp, cmd, arg);
+	ret = pcf8563_ioctl(filp, cmd, arg);
 	mutex_unlock(&pcf8563_mutex);
 
 	return ret;
diff --git a/arch/cris/arch-v32/drivers/pcf8563.c b/arch/cris/arch-v32/drivers/pcf8563.c
index b6e4fc0..208594f 100644
--- a/arch/cris/arch-v32/drivers/pcf8563.c
+++ b/arch/cris/arch-v32/drivers/pcf8563.c
@@ -341,7 +341,7 @@ static long pcf8563_unlocked_ioctl(struct file *filp, unsigned int cmd, unsigned
 	int ret;
 
 	mutex_lock(&pcf8563_mutex);
-	return pcf8563_ioctl(filp, cmd, arg);
+	ret = pcf8563_ioctl(filp, cmd, arg);
 	mutex_unlock(&pcf8563_mutex);
 
 	return ret;
--
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