From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from netops-testserver-3-out.sgi.com ([192.48.171.28]:51794 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751393AbXHNWbQ (ORCPT ); Tue, 14 Aug 2007 18:31:16 -0400 Date: Tue, 14 Aug 2007 15:31:12 -0700 (PDT) From: Christoph Lameter Subject: Re: [PATCH 0/24] make atomic_read() behave consistently across all architectures In-Reply-To: <20070809131423.GA9927@shell.boston.redhat.com> Message-ID: References: <20070809131423.GA9927@shell.boston.redhat.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-arch-owner@vger.kernel.org To: Chris Snook Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, torvalds@linux-foundation.org, 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 List-ID: On Thu, 9 Aug 2007, Chris Snook wrote: > This patchset makes the behavior of atomic_read uniform by removing the > volatile keyword from all atomic_t and atomic64_t definitions that currently > have it, and instead explicitly casts the variable as volatile in > atomic_read(). This leaves little room for creative optimization by the > compiler, and is in keeping with the principles behind "volatile considered > harmful". volatile is generally harmful even in atomic_read(). Barriers control visibility and AFAICT things are fine.