linux-kernel - Re: [PATCH] x86: fix inline assembly constraints

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Date:	Wed, 29 Oct 2008 20:54:58 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Jike Song <albcamus@...il.com>
CC:	Ingo Molnar <mingo@...e.hu>, tglx@...utronix.de, mingo@...hat.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86: fix inline assembly constraints

Jike Song wrote:
> 
> Besides, by looking at the inline assembly in kernel,  I found lots of
> codes like this:
> 
>         static inline void atomic_add(int i, atomic_t *v)
>         {
> 	        asm volatile(LOCK_PREFIX "addl %1,%0"
> 		             : "=m" (v->counter)
> 		             : "ir" (i), "m" (v->counter));
>         }
> 
> 
> Yes, it works. But a little ugly..  Should this be cleaned-up with the
> following?
> 
>         : "+m" (v->counter)
>         : "ir" (i)
> 
> If you agrees, I'll send out the patch; otherwise I won't wasting your time ;-)
> 

Please don't change them just to change them, if there is no actual
error.  You never know when you're going to trigger a new bug in some
weird version of gcc.

	-hpa
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