Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S939778AbXHIN0L (ORCPT ); Thu, 9 Aug 2007 09:26:11 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S939002AbXHINZv (ORCPT ); Thu, 9 Aug 2007 09:25:51 -0400 Received: from mx1.redhat.com ([66.187.233.31]:36931 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S936159AbXHINZu (ORCPT ); Thu, 9 Aug 2007 09:25:50 -0400 Date: Thu, 9 Aug 2007 09:24:42 -0400 From: Chris Snook To: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, torvalds@linux-foundation.org Cc: netdev@vger.kernel.org, akpm@linux-foundation.org, ak@suse.de, heiko.carstens@de.ibm.com, davem@davemloft.net, schwidefsky@de.ibm.com, wensong@linux-vs.org, horms@verge.net.au, wjiang@resilience.com, cfriesen@nortel.com, zlynx@acm.org, rpjday@mindspring.com, jesper.juhl@gmail.com Subject: [PATCH 1/24] make atomic_read() behave consistently on alpha Message-ID: <20070809132442.GA13042@shell.boston.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1723 Lines: 43 From: Chris Snook Purify volatile use for atomic[64]_t on alpha. Signed-off-by: Chris Snook --- linux-2.6.23-rc2-orig/include/asm-alpha/atomic.h 2007-07-08 19:32:17.000000000 -0400 +++ linux-2.6.23-rc2/include/asm-alpha/atomic.h 2007-08-09 09:19:00.000000000 -0400 @@ -14,18 +14,22 @@ /* - * Counter is volatile to make sure gcc doesn't try to be clever - * and move things around on us. We need to use _exactly_ the address - * the user gave us, not some alias that contains the same information. + * Make sure gcc doesn't try to be clever and move things around + * on us. We need to use _exactly_ the address the user gave us, + * not some alias that contains the same information. */ -typedef struct { volatile int counter; } atomic_t; -typedef struct { volatile long counter; } atomic64_t; +typedef struct { int counter; } atomic_t; +typedef struct { long counter; } atomic64_t; #define ATOMIC_INIT(i) ( (atomic_t) { (i) } ) #define ATOMIC64_INIT(i) ( (atomic64_t) { (i) } ) -#define atomic_read(v) ((v)->counter + 0) -#define atomic64_read(v) ((v)->counter + 0) +/* + * Casting to volatile here minimizes the need for barriers, + * without having to declare the type itself as volatile. + */ +#define atomic_read(v) (*(volatile int *)&(v)->counter + 0) +#define atomic64_read(v) (*(volatile long *)&(v)->counter + 0) #define atomic_set(v,i) ((v)->counter = (i)) #define atomic64_set(v,i) ((v)->counter = (i)) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/