[PATCH] sound/soc/fsl/fsl_dma.c: add missing of_node_put

[PATCH] sound/soc/fsl/fsl_dma.c: add missing of_node_put

[Julia Lawall]

From: Julia Lawall <julia@diku.dk>

of_parse_phandle increments the reference count of np, so this should be
decremented before trying the next possibility.

The semantic match that finds this problem is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@@
expression e,e1,e2;
@@

*e = of_parse_phandle(...)
... when != of_node_put(e)
    when != true e == NULL
    when != e2 = e
e = e1
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>

---
 sound/soc/fsl/fsl_dma.c |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/sound/soc/fsl/fsl_dma.c b/sound/soc/fsl/fsl_dma.c
index 0efc04a..b33271b 100644
--- a/sound/soc/fsl/fsl_dma.c
+++ b/sound/soc/fsl/fsl_dma.c
@@ -880,10 +880,12 @@ static struct device_node *find_ssi_node(struct device_node *dma_channel_np)
 		np = of_parse_phandle(ssi_np, "fsl,playback-dma", 0);
 		if (np == dma_channel_np)
 			return ssi_np;
+		of_node_put(np);
 
 		np = of_parse_phandle(ssi_np, "fsl,capture-dma", 0);
 		if (np == dma_channel_np)
 			return ssi_np;
+		of_node_put(np);
 	}
 
 	return NULL;

Re: [PATCH] sound/soc/fsl/fsl_dma.c: add missing of_node_put

[Liam Girdwood]

On 20/08/11 08:23, Julia Lawall wrote:
> From: Julia Lawall <julia@diku.dk>
> 
> of_parse_phandle increments the reference count of np, so this should be
> decremented before trying the next possibility.
> 
> The semantic match that finds this problem is as follows:
> (http://coccinelle.lip6.fr/)
> 
> // <smpl>
> @@
> expression e,e1,e2;
> @@
> 
> *e = of_parse_phandle(...)
> ... when != of_node_put(e)
>     when != true e == NULL
>     when != e2 = e
> e = e1
> // </smpl>
> 
> Signed-off-by: Julia Lawall <julia@diku.dk>
> 
> ---
>  sound/soc/fsl/fsl_dma.c |    2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/sound/soc/fsl/fsl_dma.c b/sound/soc/fsl/fsl_dma.c
> index 0efc04a..b33271b 100644
> --- a/sound/soc/fsl/fsl_dma.c
> +++ b/sound/soc/fsl/fsl_dma.c
> @@ -880,10 +880,12 @@ static struct device_node *find_ssi_node(struct device_node *dma_channel_np)
>  		np = of_parse_phandle(ssi_np, "fsl,playback-dma", 0);
>  		if (np == dma_channel_np)
>  			return ssi_np;
> +		of_node_put(np);
>  
>  		np = of_parse_phandle(ssi_np, "fsl,capture-dma", 0);
>  		if (np == dma_channel_np)
>  			return ssi_np;
> +		of_node_put(np);
>  	}
>  
>  	return NULL;
> 

Acked-by: Liam Girdwood <lrg@ti.com>

Re: [PATCH] sound/soc/fsl/fsl_dma.c: add missing of_node_put

[Timur Tabi]

Julia Lawall wrote:
> diff --git a/sound/soc/fsl/fsl_dma.c b/sound/soc/fsl/fsl_dma.c
> index 0efc04a..b33271b 100644
> --- a/sound/soc/fsl/fsl_dma.c
> +++ b/sound/soc/fsl/fsl_dma.c
> @@ -880,10 +880,12 @@ static struct device_node *find_ssi_node(struct device_node *dma_channel_np)
>  		np = of_parse_phandle(ssi_np, "fsl,playback-dma", 0);
>  		if (np == dma_channel_np)
>  			return ssi_np;
> +		of_node_put(np);
>  
>  		np = of_parse_phandle(ssi_np, "fsl,capture-dma", 0);
>  		if (np == dma_channel_np)
>  			return ssi_np;
> +		of_node_put(np);
>  	}

Thanks for catching the problem, Julia, but the fix is not quite correct.  My
code assumes that of_parse_phandle() doesn't claim the node, but it doesn't
actually use the node pointer, either.  All I care about is whether 'np' is
equal to dma_channel_np.  I'm not going to use 'np'.  So I think the real fix is
this:

@@ -880,10 +880,12 @@ static struct device_node *find_ssi_node(struct
device_node *dma_channel_np)
 		np = of_parse_phandle(ssi_np, "fsl,playback-dma", 0);
+		of_node_put(np);
 		if (np == dma_channel_np)
 			return ssi_np;

 		np = of_parse_phandle(ssi_np, "fsl,capture-dma", 0);
+		of_node_put(np);
 		if (np == dma_channel_np)
 			return ssi_np;
 	}

 	return NULL;

-- 
Timur Tabi
Linux kernel developer at Freescale

Re: [PATCH] sound/soc/fsl/fsl_dma.c: add missing of_node_put

[Julia Lawall]

On Mon, 22 Aug 2011, Timur Tabi wrote:

> Julia Lawall wrote:
> > diff --git a/sound/soc/fsl/fsl_dma.c b/sound/soc/fsl/fsl_dma.c
> > index 0efc04a..b33271b 100644
> > --- a/sound/soc/fsl/fsl_dma.c
> > +++ b/sound/soc/fsl/fsl_dma.c
> > @@ -880,10 +880,12 @@ static struct device_node *find_ssi_node(struct device_node *dma_channel_np)
> >  		np = of_parse_phandle(ssi_np, "fsl,playback-dma", 0);
> >  		if (np == dma_channel_np)
> >  			return ssi_np;
> > +		of_node_put(np);
> >  
> >  		np = of_parse_phandle(ssi_np, "fsl,capture-dma", 0);
> >  		if (np == dma_channel_np)
> >  			return ssi_np;
> > +		of_node_put(np);
> >  	}
> 
> Thanks for catching the problem, Julia, but the fix is not quite correct.  My
> code assumes that of_parse_phandle() doesn't claim the node, but it doesn't
> actually use the node pointer, either.  All I care about is whether 'np' is
> equal to dma_channel_np.  I'm not going to use 'np'.  So I think the real fix is
> this:
> 
> @@ -880,10 +880,12 @@ static struct device_node *find_ssi_node(struct
> device_node *dma_channel_np)
>  		np = of_parse_phandle(ssi_np, "fsl,playback-dma", 0);
> +		of_node_put(np);
>  		if (np == dma_channel_np)
>  			return ssi_np;
> 
>  		np = of_parse_phandle(ssi_np, "fsl,capture-dma", 0);
> +		of_node_put(np);
>  		if (np == dma_channel_np)
>  			return ssi_np;
>  	}
> 
>  	return NULL;

OK, that looks reasonable.

julia