linux-kernel - Re: [Patch 09/16] Remove unnecessary kmalloc casts in the pci subsystem.

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Message-ID: <20070731161051.GA7490@suse.de>
Date:	Tue, 31 Jul 2007 09:10:51 -0700
From:	Greg KH <gregkh@...e.de>
To:	WANG Cong <xiyou.wangcong@...il.com>
Cc:	Satyam Sharma <satyam@...radead.org>,
	Christian Borntraeger <borntraeger@...ibm.com>,
	jack@...keye.stone.uk.eu.org, linux-kernel@...r.kernel.org,
	trivial@...nel.org
Subject: Re: [Patch 09/16] Remove unnecessary kmalloc casts in the pci
	subsystem.

On Tue, Jul 31, 2007 at 10:46:19PM +0800, WANG Cong wrote:
> On Tue, Jul 31, 2007 at 08:00:12PM +0530, Satyam Sharma wrote:
> >
> >
> >On Tue, 31 Jul 2007, Christian Borntraeger wrote:
> >
> >> Am Dienstag, 31. Juli 2007 schrieb jack@...keye.stone.uk.eu.org:
> >> > --- a/drivers/pci/rom.c
> >> > +++ b/drivers/pci/rom.c
> >> > @@ -185,7 +185,7 @@ void __iomem *pci_map_rom_copy(struct pc
> >> >  			  IORESOURCE_ROM_BIOS_COPY))
> >> >  		return rom;
> >> > 
> >> > -	res->start = (unsigned long)kmalloc(*size, GFP_KERNEL);
> >> > +	res->start = kmalloc(*size, GFP_KERNEL);
> >> 
> >> This looks wrong.
> >
> >Yup, a warning at the very least.
> >
> >> void * doesnt need a cast to a pointer, but res->start is an 
> >> integer u32 type,
> >
> >It better not be, else we have a bug already anyway. Pointers are 64-bit
> >on 64-bit archs. [ it turns out res->start is resource_size_t which is
> >set properly as per CONFIG_RESOURCES_64BIT which itself is set properly
> >as per CONFIG_64BIT, so everything is healthy and fine :-) ]
> >
> 
> I agree.
> 
> However, I think using resource_size_t is a bit better than unsigned long,
> so that we don't need to check the defination of it.
> 
> - res->start = (unsigned long)kmalloc(*size, GFP_KERNEL);
> + res->start = (resource_size_t)kmalloc(*size, GFP_KERNEL);
> 
> Is this change OK?

Yes, that is the proper cast to have here.

thanks,

greg k-h
-
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