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Date: Fri, 22 Feb 2002 12:08:25 +0100
From: Steffen Persvold <sp@scali.com>
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To: "Jeff V. Merkey" <jmerkey@vger.timpanogas.org>
CC: linux-kernel@vger.kernel.org, jmerkey@timpanogas.org
Subject: Re: ioremap()/PCI sickness in 2.4.18-rc2 (FIXED ALMOST)
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"Jeff V. Merkey" wrote:
> 
> On Wed, Feb 20, 2002 at 02:54:49PM -0700, Jeff V. Merkey wrote:
> 
> > struct vm_struct * get_vm_area(unsigned long size, unsigned long flags)
> > {
> >       unsigned long addr;
> >       struct vm_struct **p, *tmp, *area;
> >
> >       area = (struct vm_struct *) kmalloc(sizeof(*area), GFP_KERNEL);
> >       if (!area)
> >               return NULL;
> >       size += PAGE_SIZE;
> >       addr = VMALLOC_START;
> >       write_lock(&vmlist_lock);
> >       for (p = &vmlist; (tmp = *p) ; p = &tmp->next) {
> >
> > ===============>  we barf here since the size + addr wraps
> >
> 
> Also, this function should be moved to the /arch/i386/mm area since
> it is doing pointer arithmetic with 32 bit assumptions (i.e.
> unsigned long + unsigned long)  Last time I checked, unsigned long
> was a construct for a 32 bit value in any gcc compiler version, ia64
> or not.
> 

Jeff,

I think you'll have to check again. In LP64 programming models (used on most
64-bit OS'es) 'long' is 64 bit. Thus a 'unsigned long' is always safe to use
for pointer arithmetic since it will be 32 bit on 32bit machines and 64bit on
64bit machines.

Regards,
-- 
  Steffen Persvold   | Scalable Linux Systems |   Try out the world's best
 mailto:sp@scali.com |  http://www.scali.com  | performing MPI implementation:
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