[3/4] drivers/net/can/mscan/mpc5xxx_can.c: Add of_node_put to avoid memory leak

Add a call to of_node_put in the error handling code following a call to
of_find_matching_node.

This patch also moves the existing call to of_node_put after the call to
iounmap in the error handling code, to make it possible to jump to
of_node_put without doing iounmap.  These appear to be disjoint operations,
so the ordering doesn't matter.

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

// <smpl>
@r exists@
local idexpression x;
expression E,E1,E2;
statement S;
@@

*x = 
(of_find_node_by_path
|of_find_node_by_name
|of_find_node_by_phandle
|of_get_parent
|of_get_next_parent
|of_get_next_child
|of_find_compatible_node
|of_match_node
|of_find_node_by_type
|of_find_node_with_property
|of_find_matching_node
|of_parse_phandle
)(...);
...
if (x == NULL) S
<... when != x = E
*if (...) {
  ... when != of_node_put(x)
      when != if (...) { ... of_node_put(x); ... }
(
  return <+...x...+>;
|
*  return ...;
)
}
...>
(
E2 = x;
|
of_node_put(x);
)
// </smpl>

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

---
 drivers/net/can/mscan/mpc5xxx_can.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)


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On Tue, Aug 31, 2010 at 05:48:57PM +0200, Julia Lawall wrote:
> Add a call to of_node_put in the error handling code following a call to
> of_find_matching_node.
> 
> This patch also moves the existing call to of_node_put after the call to
> iounmap in the error handling code, to make it possible to jump to
> of_node_put without doing iounmap.  These appear to be disjoint operations,
> so the ordering doesn't matter.

Hmm, the function you change returns -ENODEV if a clock cannot be found, but
the return type is u32. This should better be 0. Can you take care of this as
well? You could then add my

Reviewed-by: Wolfram Sang <w.sang@pengutronix.de>

> 
> The semantic match that finds this problem is as follows:
> (http://coccinelle.lip6.fr/)
> 
> // <smpl>
> @r exists@
> local idexpression x;
> expression E,E1,E2;
> statement S;
> @@
> 
> *x = 
> (of_find_node_by_path
> |of_find_node_by_name
> |of_find_node_by_phandle
> |of_get_parent
> |of_get_next_parent
> |of_get_next_child
> |of_find_compatible_node
> |of_match_node
> |of_find_node_by_type
> |of_find_node_with_property
> |of_find_matching_node
> |of_parse_phandle
> )(...);
> ...
> if (x == NULL) S
> <... when != x = E
> *if (...) {
>   ... when != of_node_put(x)
>       when != if (...) { ... of_node_put(x); ... }
> (
>   return <+...x...+>;
> |
> *  return ...;
> )
> }
> ...>
> (
> E2 = x;
> |
> of_node_put(x);
> )
> // </smpl>
> 
> Signed-off-by: Julia Lawall <julia@diku.dk>
> 
> ---
>  drivers/net/can/mscan/mpc5xxx_can.c |    6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/can/mscan/mpc5xxx_can.c b/drivers/net/can/mscan/mpc5xxx_can.c
> index b1bdc90..883959c 100644
> --- a/drivers/net/can/mscan/mpc5xxx_can.c
> +++ b/drivers/net/can/mscan/mpc5xxx_can.c
> @@ -148,7 +148,7 @@ static u32 __devinit mpc512x_can_get_clock(struct platform_device *ofdev,
>  	clockctl = of_iomap(np_clock, 0);
>  	if (!clockctl) {
>  		dev_err(&ofdev->dev, "couldn't map clock registers\n");
> -		return 0;
> +		goto exit_put;
>  	}
>  
>  	/* Determine the MSCAN device index from the physical address */
> @@ -233,9 +233,9 @@ static u32 __devinit mpc512x_can_get_clock(struct platform_device *ofdev,
>  		clocksrc == 1 ? "ref_clk" : "sys_clk", clockdiv);
>  
>  exit_unmap:
> -	of_node_put(np_clock);
>  	iounmap(clockctl);
> -
> +exit_put:
> +	of_node_put(np_clock);
>  	return freq;
>  }
>  #else /* !CONFIG_PPC_MPC512x */
> 
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On Tue, 31 Aug 2010, Wolfram Sang wrote:

> On Tue, Aug 31, 2010 at 05:48:57PM +0200, Julia Lawall wrote:
> > Add a call to of_node_put in the error handling code following a call to
> > of_find_matching_node.
> > 
> > This patch also moves the existing call to of_node_put after the call to
> > iounmap in the error handling code, to make it possible to jump to
> > of_node_put without doing iounmap.  These appear to be disjoint operations,
> > so the ordering doesn't matter.
> 
> Hmm, the function you change returns -ENODEV if a clock cannot be found, but
> the return type is u32. This should better be 0. Can you take care of this as
> well?

I'll look at it.  I was trying to make the returned value be signed, which 
seemed to have some slightly complicated repercussions, but a return value 
of 0 may work out much better.

julia
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