linux-kernel - Re: [PATCH 6/24] make atomic_read() behave consistently on frv

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Message-ID: <20070814072617.GA8766@gondor.apana.org.au>
Date:	Tue, 14 Aug 2007 15:26:17 +0800
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	Nick Piggin <nickpiggin@...oo.com.au>
Cc:	paulmck@...ux.vnet.ibm.com, csnook@...hat.com, dhowells@...hat.com,
	linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
	torvalds@...ux-foundation.org, netdev@...r.kernel.org,
	akpm@...ux-foundation.org, ak@...e.de, heiko.carstens@...ibm.com,
	davem@...emloft.net, schwidefsky@...ibm.com, wensong@...ux-vs.org,
	horms@...ge.net.au, wjiang@...ilience.com, cfriesen@...tel.com,
	zlynx@....org, rpjday@...dspring.com, jesper.juhl@...il.com
Subject: Re: [PATCH 6/24] make atomic_read() behave consistently on frv

On Tue, Aug 14, 2007 at 03:34:25PM +1000, Nick Piggin wrote:
>
> What do you think of this crazy idea?
> 
> /* Enforce a compiler barrier for only operations to location X.
>  * Call multiple times to provide an ordering between multiple
>  * memory locations. Other memory operations can be assumed by
>  * the compiler to remain unchanged and may be reordered
>  */
> #define order(x) asm volatile("" : "+m" (x))

Yes this is a very good idea.  This also makes it explicit
that the coder is depending on this rather than the more
vague connotations of atomic_read.

Cheers,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
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