[PATCH] OSS: mpu401, fix deadlock

[PATCH] OSS: mpu401, fix deadlock

[Jiri Slaby]

If somebody cares about oss at all.
--
mpu401_chk_version is called with a spin lock already held. Don't take it
again.

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
---
 sound/oss/mpu401.c |   16 +++-------------
 1 files changed, 3 insertions(+), 13 deletions(-)

diff --git a/sound/oss/mpu401.c b/sound/oss/mpu401.c
index 6c0a770..1b2316f 100644
--- a/sound/oss/mpu401.c
+++ b/sound/oss/mpu401.c
@@ -926,31 +926,21 @@ static struct midi_operations mpu401_midi_operations[MAX_MIDI_DEV];
 static void mpu401_chk_version(int n, struct mpu_config *devc)
 {
 	int tmp;
-	unsigned long flags;
 
 	devc->version = devc->revision = 0;
 
-	spin_lock_irqsave(&devc->lock,flags);
-	if ((tmp = mpu_cmd(n, 0xAC, 0)) < 0)
-	{
-		spin_unlock_irqrestore(&devc->lock,flags);
+	tmp = mpu_cmd(n, 0xAC, 0);
+	if (tmp < 0)
 		return;
-	}
 	if ((tmp & 0xf0) > 0x20)	/* Why it's larger than 2.x ??? */
-	{
-		spin_unlock_irqrestore(&devc->lock,flags);
 		return;
-	}
 	devc->version = tmp;
 
-	if ((tmp = mpu_cmd(n, 0xAD, 0)) < 0)
-	{
+	if ((tmp = mpu_cmd(n, 0xAD, 0)) < 0) {
 		devc->version = 0;
-		spin_unlock_irqrestore(&devc->lock,flags);
 		return;
 	}
 	devc->revision = tmp;
-	spin_unlock_irqrestore(&devc->lock,flags);
 }
 
 int attach_mpu401(struct address_info *hw_config, struct module *owner)
-- 
1.6.3.2

Re: [PATCH] OSS: mpu401, fix deadlock

[Takashi Iwai]

At Mon, 29 Jun 2009 18:03:34 +0200,
Jiri Slaby wrote:
> 
> If somebody cares about oss at all.

... or want to save somebody else's time to find out the same bug :)

> --
> mpu401_chk_version is called with a spin lock already held. Don't take it
> again.
> 
> Signed-off-by: Jiri Slaby <jirislaby@gmail.com>

Applied now.  Thanks.


Takashi

> ---
>  sound/oss/mpu401.c |   16 +++-------------
>  1 files changed, 3 insertions(+), 13 deletions(-)
> 
> diff --git a/sound/oss/mpu401.c b/sound/oss/mpu401.c
> index 6c0a770..1b2316f 100644
> --- a/sound/oss/mpu401.c
> +++ b/sound/oss/mpu401.c
> @@ -926,31 +926,21 @@ static struct midi_operations mpu401_midi_operations[MAX_MIDI_DEV];
>  static void mpu401_chk_version(int n, struct mpu_config *devc)
>  {
>  	int tmp;
> -	unsigned long flags;
>  
>  	devc->version = devc->revision = 0;
>  
> -	spin_lock_irqsave(&devc->lock,flags);
> -	if ((tmp = mpu_cmd(n, 0xAC, 0)) < 0)
> -	{
> -		spin_unlock_irqrestore(&devc->lock,flags);
> +	tmp = mpu_cmd(n, 0xAC, 0);
> +	if (tmp < 0)
>  		return;
> -	}
>  	if ((tmp & 0xf0) > 0x20)	/* Why it's larger than 2.x ??? */
> -	{
> -		spin_unlock_irqrestore(&devc->lock,flags);
>  		return;
> -	}
>  	devc->version = tmp;
>  
> -	if ((tmp = mpu_cmd(n, 0xAD, 0)) < 0)
> -	{
> +	if ((tmp = mpu_cmd(n, 0xAD, 0)) < 0) {
>  		devc->version = 0;
> -		spin_unlock_irqrestore(&devc->lock,flags);
>  		return;
>  	}
>  	devc->revision = tmp;
> -	spin_unlock_irqrestore(&devc->lock,flags);
>  }
>  
>  int attach_mpu401(struct address_info *hw_config, struct module *owner)
> -- 
> 1.6.3.2
>