[PATCH 9/9] sound/soc/codecs: Correct code taking the size of a

[PATCH 9/9] sound/soc/codecs: Correct code taking the size of a

[Julia Lawall]

From: Julia Lawall <julia@diku.dk>

sizeof(codec->reg_cache) is just the size of the pointer.  Elsewhere in the
file, codec->reg_cache is used with sizeof(wm8900_reg_defaults), so the
code is changed to do the same here.

A simplified version of the semantic patch that finds this problem is as
follows: (http://coccinelle.lip6.fr/)

// <smpl>
@@
expression *x;
expression f;
type T;
@@

*f(...,(T)x,...)
// </smpl>

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

---
 sound/soc/codecs/wm8900.c           |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/sound/soc/codecs/wm8900.c b/sound/soc/codecs/wm8900.c
index c9438dd..dbc368c 100644
--- a/sound/soc/codecs/wm8900.c
+++ b/sound/soc/codecs/wm8900.c
@@ -199,7 +199,7 @@ static void wm8900_reset(struct snd_soc_codec *codec)
 	snd_soc_write(codec, WM8900_REG_RESET, 0);
 
 	memcpy(codec->reg_cache, wm8900_reg_defaults,
-	       sizeof(codec->reg_cache));
+	       sizeof(wm8900_reg_defaults));
 }
 
 static int wm8900_hp_event(struct snd_soc_dapm_widget *w,

Re: [PATCH 9/9] sound/soc/codecs: Correct code taking the size of

[walter harms]

Julia Lawall schrieb:
> From: Julia Lawall <julia@diku.dk>
> 
> sizeof(codec->reg_cache) is just the size of the pointer.  Elsewhere in the
> file, codec->reg_cache is used with sizeof(wm8900_reg_defaults), so the
> code is changed to do the same here.
> 
> A simplified version of the semantic patch that finds this problem is as
> follows: (http://coccinelle.lip6.fr/)
> 
> // <smpl>
> @@
> expression *x;
> expression f;
> type T;
> @@
> 
> *f(...,(T)x,...)
> // </smpl>
> 
> Signed-off-by: Julia Lawall <julia@diku.dk>
> 
> ---
>  sound/soc/codecs/wm8900.c           |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/sound/soc/codecs/wm8900.c b/sound/soc/codecs/wm8900.c
> index c9438dd..dbc368c 100644
> --- a/sound/soc/codecs/wm8900.c
> +++ b/sound/soc/codecs/wm8900.c
> @@ -199,7 +199,7 @@ static void wm8900_reset(struct snd_soc_codec *codec)
>  	snd_soc_write(codec, WM8900_REG_RESET, 0);
>  
>  	memcpy(codec->reg_cache, wm8900_reg_defaults,
> -	       sizeof(codec->reg_cache));
> +	       sizeof(wm8900_reg_defaults));
>  }

I do not think that this was the intention of the original author,
I guess the idea behind sizeof(*codec->reg_cache) was to protect
the area behind it (in case wm8900_reg_defaults are badly defined).

re,
 wh

Re: [PATCH 9/9] sound/soc/codecs: Correct code taking the size of

[Julia Lawall]

On Sun, 13 Dec 2009, walter harms wrote:

> 
> 
> Julia Lawall schrieb:
> > From: Julia Lawall <julia@diku.dk>
> > 
> > sizeof(codec->reg_cache) is just the size of the pointer.  Elsewhere in the
> > file, codec->reg_cache is used with sizeof(wm8900_reg_defaults), so the
> > code is changed to do the same here.
> > 
> > A simplified version of the semantic patch that finds this problem is as
> > follows: (http://coccinelle.lip6.fr/)
> > 
> > // <smpl>
> > @@
> > expression *x;
> > expression f;
> > type T;
> > @@
> > 
> > *f(...,(T)x,...)
> > // </smpl>
> > 
> > Signed-off-by: Julia Lawall <julia@diku.dk>
> > 
> > ---
> >  sound/soc/codecs/wm8900.c           |    2 +-
> >  1 files changed, 1 insertions(+), 1 deletions(-)
> > 
> > diff --git a/sound/soc/codecs/wm8900.c b/sound/soc/codecs/wm8900.c
> > index c9438dd..dbc368c 100644
> > --- a/sound/soc/codecs/wm8900.c
> > +++ b/sound/soc/codecs/wm8900.c
> > @@ -199,7 +199,7 @@ static void wm8900_reset(struct snd_soc_codec *codec)
> >  	snd_soc_write(codec, WM8900_REG_RESET, 0);
> >  
> >  	memcpy(codec->reg_cache, wm8900_reg_defaults,
> > -	       sizeof(codec->reg_cache));
> > +	       sizeof(wm8900_reg_defaults));
> >  }
> 
> I do not think that this was the intention of the original author,
> I guess the idea behind sizeof(*codec->reg_cache) was to protect
> the area behind it (in case wm8900_reg_defaults are badly defined).

sizeof(codec->reg_cache) is the size of a pointer (void *).  
sizeof(*codec->reg_cache) is then the size of void.  wm8900_reg_defaults 
is a static constant array defined a few lines before this code:

static const u16 wm8900_reg_defaults[WM8900_MAXREG] = { ... };

Later in the same file there is:

 cache = kmemdup(codec->reg_cache, sizeof(wm8900_reg_defaults),
                       GFP_KERNEL);

and codec->reg_cache is initialized as follows:

  codec->reg_cache = &wm8900->reg_cache[0];

The reg_cache field in wm8900 is declared as u16 reg_cache[WM8900_MAXREG];

julia

Re: [PATCH 9/9] sound/soc/codecs: Correct code taking the size of

[Mark Brown]

On Sun, Dec 13, 2009 at 12:43:15PM +0100, Julia Lawall wrote:
> From: Julia Lawall <julia@diku.dk>
> 
> sizeof(codec->reg_cache) is just the size of the pointer.  Elsewhere in the
> file, codec->reg_cache is used with sizeof(wm8900_reg_defaults), so the
> code is changed to do the same here.

Applied, thanks.