linux-kernel - Re: [PATCH] drivers/rtc/rtc-mrst.c: Use release_mem_region after request_mem

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Message-ID: <Pine.LNX.4.64.1104080657520.16547@ask.diku.dk>
Date:	Fri, 8 Apr 2011 07:14:48 +0200 (CEST)
From:	Julia Lawall <julia@...u.dk>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Alessandro Zummo <a.zummo@...ertech.it>,
	kernel-janitors@...r.kernel.org, rtc-linux@...glegroups.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drivers/rtc/rtc-mrst.c: Use release_mem_region after
 request_mem_region

On Thu, 7 Apr 2011, Andrew Morton wrote:

> On Mon, 14 Mar 2011 22:00:25 +0100
> Julia Lawall <julia@...u.dk> wrote:
> 
> > The memory allocated using request_mem_region should be released using
> > release_mem_region, not release_region.
> > 
> > The semantic patch that fixes part of this problem is as follows:
> > (http://coccinelle.lip6.fr/)
> > 
> > // <smpl>
> > @@
> > expression E1,E2,E3;
> > @@
> > 
> > request_mem_region(E1,E2,E3)
> > ...
> > ?- release_region(E1,E2)
> > + release_mem_region(E1,E2)
> > // </smpl>
> > 
> > Signed-off-by: Julia Lawall <julia@...u.dk>
> > 
> > ---
> >  drivers/rtc/rtc-mrst.c |    4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/rtc/rtc-mrst.c b/drivers/rtc/rtc-mrst.c
> > index b86bc32..558dd7d 100644
> > --- a/drivers/rtc/rtc-mrst.c
> > +++ b/drivers/rtc/rtc-mrst.c
> > @@ -379,7 +379,7 @@ cleanup1:
> >  	mrst_rtc.dev = NULL;
> >  	rtc_device_unregister(mrst_rtc.rtc);
> >  cleanup0:
> > -	release_region(iomem->start, iomem->end + 1 - iomem->start);
> > +	release_mem_region(iomem->start, iomem->end + 1 - iomem->start);
> >  	dev_err(dev, "rtc-mrst: unable to initialise\n");
> >  	return retval;
> >  }
> > @@ -405,7 +405,7 @@ static void __exit rtc_mrst_do_remove(struct device *dev)
> >  	mrst->rtc = NULL;
> >  
> >  	iomem = mrst->iomem;
> > -	release_region(iomem->start, iomem->end + 1 - iomem->start);
> > +	release_mem_region(iomem->start, iomem->end + 1 - iomem->start);
> >  	mrst->iomem = NULL;
> >  
> >  	mrst->dev = NULL;
> 
> We may as well clean this up too.
> 
> --- a/drivers/rtc/rtc-mrst.c~drivers-rtc-rtc-mrstc-use-release_mem_region-after-request_mem_region-fix
> +++ a/drivers/rtc/rtc-mrst.c
> @@ -380,7 +380,7 @@ cleanup1:
>  cleanup0:
>  	dev_set_drvdata(dev, NULL);
>  	mrst_rtc.dev = NULL;
> -	release_mem_region(iomem->start, iomem->end + 1 - iomem->start);
> +	release_mem_region(iomem->start, resource_size(iomem));
>  	dev_err(dev, "rtc-mrst: unable to initialise\n");
>  	return retval;
>  }
> @@ -406,7 +406,7 @@ static void __devexit rtc_mrst_do_remove
>  	mrst->rtc = NULL;
>  
>  	iomem = mrst->iomem;
> -	release_mem_region(iomem->start, iomem->end + 1 - iomem->start);
> +	release_mem_region(iomem->start, resource_size(iomem));
>  	mrst->iomem = NULL;
>  
>  	mrst->dev = NULL;
> _
> 
> which makes one wonder why we don't have
> 
> void release_resource_mem(struct resource *r)
> {
> 	release_mem_region(r->start, resource_size(r));
> }

Perhaps the name is not quite good, because release resource is something 
different from:

void release_resource(struct resource *r)
{
      release_region(r->start, resource_size(r));
}

It would be really nice to have such a wrapper for both of them, since the 
code is so common, and the size computation is so error prone.

julia
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