From: Andi Kleen <ak@suse.de>
To: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Subject: Re: [patch] avoid unaligned access when accessing poll stack
Date: Fri, 31 Mar 2006 18:53:32 +0200
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Cc: Jes Sorensen <jes@sgi.com>, Linus Torvalds <torvalds@osdl.org>,
       Andrew Morton <akpm@osdl.org>, linux-kernel@vger.kernel.org,
       linux-ia64@vger.kernel.org
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On Friday 31 March 2006 18:37, OGAWA Hirofumi wrote:
> Jes Sorensen <jes@sgi.com> writes:
> 
> >   	struct poll_list *walk;
> >  	struct fdtable *fdt;
> >  	int max_fdset;
> > -	/* Allocate small arguments on the stack to save memory and be faster */
> > -	char stack_pps[POLL_STACK_ALLOC];
> > +	/* Allocate small arguments on the stack to save memory and be 
> > +	   faster - use long to make sure the buffer is aligned properly
> > +	   on 64 bit archs to avoid unaligned access */
> > +	long stack_pps[POLL_STACK_ALLOC/sizeof(long)];
> >  	struct poll_list *stack_pp = NULL;
> 
> struct poll_list stack_pps[POLL_STACK_ALLOC / sizeof(struct poll_list)];
> 
> is more readable, and probably gcc align it rightly?

Yes, but it would be wrong

-Andi

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