netdev - Re: [PATCH 3/4] drivers/net/can/mscan/mpc5xxx_can.c: Add of_node

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Date:	Tue, 31 Aug 2010 21:10:14 +0200
From:	Wolfram Sang <w.sang@...gutronix.de>
To:	Julia Lawall <julia@...u.dk>
Cc:	Wolfgang Grandegger <wg@...ndegger.com>,
	kernel-janitors@...r.kernel.org,
	Grant Likely <grant.likely@...retlab.ca>,
	socketcan-core@...ts.berlios.de, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, devicetree-discuss@...ts.ozlabs.org
Subject: Re: [PATCH 3/4] drivers/net/can/mscan/mpc5xxx_can.c: Add
	of_node_put to avoid memory leak

On Tue, Aug 31, 2010 at 07:44:00PM +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.
> 
> This patch furthermore changes the -ENODEV result in the error handling
> code for of_find_matching_node to a return of 0, as found in the error
> handling code for of_iomap, because the return type of the function is
> unsigned.
> 
> 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@...u.dk>

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

> 
> ---
>  drivers/net/can/mscan/mpc5xxx_can.c |    8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/can/mscan/mpc5xxx_can.c b/drivers/net/can/mscan/mpc5xxx_can.c
> --- a/drivers/net/can/mscan/mpc5xxx_can.c
> +++ b/drivers/net/can/mscan/mpc5xxx_can.c
> @@ -143,12 +143,12 @@ static u32 __devinit mpc512x_can_get_clock(struct platform_device *ofdev,
>  	np_clock = of_find_matching_node(NULL, mpc512x_clock_ids);
>  	if (!np_clock) {
>  		dev_err(&ofdev->dev, "couldn't find clock node\n");
> -		return -ENODEV;
> +		return 0;
>  	}
>  	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 */

-- 
Pengutronix e.K.                           | Wolfram Sang                |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

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