From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Snook Subject: [PATCH 16/24] make atomic_read() behave consistently on s390 Date: Thu, 9 Aug 2007 10:06:55 -0400 Message-ID: <20070809140655.GA17731@shell.boston.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii 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 To: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, torvalds@linux-foundation.org Return-path: Received: from mx1.redhat.com ([66.187.233.31]:52284 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S938318AbXHIOHZ (ORCPT ); Thu, 9 Aug 2007 10:07:25 -0400 Content-Disposition: inline Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org From: Chris Snook Make atomic[64]_read() volatile on s390, to ensure memory is actually read each time. Signed-off-by: Chris Snook --- linux-2.6.23-rc2-orig/include/asm-s390/atomic.h 2007-08-08 17:48:53.000000000 -0400 +++ linux-2.6.23-rc2/include/asm-s390/atomic.h 2007-08-09 07:18:56.000000000 -0400 @@ -67,7 +67,11 @@ typedef struct { #endif /* __GNUC__ */ -#define atomic_read(v) ((v)->counter) +/* + * 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) #define atomic_set(v,i) (((v)->counter) = (i)) static __inline__ int atomic_add_return(int i, atomic_t * v) @@ -182,7 +186,7 @@ typedef struct { #endif /* __GNUC__ */ -#define atomic64_read(v) ((v)->counter) +#define atomic64_read(v) (*(volatile long long *)&(v)->counter) #define atomic64_set(v,i) (((v)->counter) = (i)) static __inline__ long long atomic64_add_return(long long i, atomic64_t * v)