linux-kernel - Re: [PATCH 5/5] drivers/i2c/busses/i2c-nuc900.c: Convert release_resource to release_region/release_mem

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Date:	Mon, 14 Feb 2011 17:56:18 +0100
From:	Marek Vasut <marek.vasut@...il.com>
To:	Julia Lawall <julia@...u.dk>
Cc:	ben-linux@...ff.org, kernel-janitors@...r.kernel.org,
	Baruch Siach <baruch@...s.co.il>,
	Dave Airlie <airlied@...ux.ie>, linux-i2c@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/5] drivers/i2c/busses/i2c-nuc900.c: Convert release_resource to release_region/release_mem_region

On Sunday 13 February 2011 13:12:12 Julia Lawall wrote:
> Request_region should be used with release_region, not release_resource.
> 
> The result of request_mem_region is no longer stored.  Instead the field
> ioarea is used to store a pointer to the resource structure that contains
> the start address.  This is the information that is needed later in
> nuc900_i2c_remove to release the region.  The field ioarea is also printed
> in some debugging code.
> 
> The semantic match that finds this problem is as follows:
> (http://coccinelle.lip6.fr/)
> 
> // <smpl>
> @@
> expression x,E;
> @@
> (
> *x = request_region(...)
> 
> *x = request_mem_region(...)
> )
> ... when != release_region(x)
>     when != x = E
> * release_resource(x);
> // </smpl>
> 
> Signed-off-by: Julia Lawall <julia@...u.dk>
> 
> ---
> Not compiled due to incompatible architecture.
> 
>  drivers/i2c/busses/i2c-nuc900.c |   13 +++++--------
>  1 file changed, 5 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-nuc900.c
> b/drivers/i2c/busses/i2c-nuc900.c index 7243426..97b16b7 100644
> --- a/drivers/i2c/busses/i2c-nuc900.c
> +++ b/drivers/i2c/busses/i2c-nuc900.c
> @@ -568,15 +568,13 @@ static int __devinit nuc900_i2c_probe(struct
> platform_device *pdev) goto err_clk;
>  	}
> 
> -	i2c->ioarea = request_mem_region(res->start, resource_size(res),
> -					 pdev->name);
> -
> -	if (i2c->ioarea == NULL) {
> +	if (!request_mem_region(res->start, resource_size(res), pdev->name)) {

I prefer the original version here -- it's clearer and also, doesn't the new 
version violate line-over-80 principle ?

>  		dev_err(&pdev->dev, "cannot request IO\n");
>  		ret = -ENXIO;
>  		goto err_clk;
>  	}
> 
> +	i2c->ioarea = res;
>  	i2c->regs = ioremap(res->start, resource_size(res));
> 
>  	if (i2c->regs == NULL) {
> @@ -645,8 +643,7 @@ static int __devinit nuc900_i2c_probe(struct
> platform_device *pdev) iounmap(i2c->regs);
> 
>   err_ioarea:
> -	release_resource(i2c->ioarea);
> -	kfree(i2c->ioarea);
> +	release_mem_region(res->start, resource_size(res));
> 
>   err_clk:
>  	clk_disable(i2c->clk);
> @@ -665,6 +662,7 @@ static int __devinit nuc900_i2c_probe(struct
> platform_device *pdev) static int __devexit nuc900_i2c_remove(struct
> platform_device *pdev) {
>  	struct nuc900_i2c *i2c = platform_get_drvdata(pdev);
> +	struct resource *res = i2c->ioarea;

No need for this ...
> 
>  	i2c_del_adapter(&i2c->adap);
>  	free_irq(i2c->irq, i2c);
> @@ -674,8 +672,7 @@ static int __devexit nuc900_i2c_remove(struct
> platform_device *pdev)
> 
>  	iounmap(i2c->regs);
> 
> -	release_resource(i2c->ioarea);
> -	kfree(i2c->ioarea);

... the i2c pointer is still available here, why introducing struct resource 
*res. release_mem_region() looks like a sane change to me though.

> +	release_mem_region(res->start, resource_size(res));
>  	kfree(i2c);
> 
>  	return 0;
--
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