From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([66.187.233.31]:26053 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S932234AbWCHSfZ (ORCPT ); Wed, 8 Mar 2006 13:35:25 -0500 From: David Howells In-Reply-To: <20060308173605.GB13063@devserv.devel.redhat.com> References: <20060308173605.GB13063@devserv.devel.redhat.com> <20060308145506.GA5095@devserv.devel.redhat.com> <31492.1141753245@warthog.cambridge.redhat.com> <29826.1141828678@warthog.cambridge.redhat.com> <9834.1141837491@warthog.cambridge.redhat.com> Subject: Re: [PATCH] Document Linux's memory barriers [try #2] Date: Wed, 08 Mar 2006 18:35:07 +0000 Message-ID: <11922.1141842907@warthog.cambridge.redhat.com> Sender: linux-arch-owner@vger.kernel.org To: Alan Cox Cc: David Howells , torvalds@osdl.org, akpm@osdl.org, mingo@redhat.com, linux-arch@vger.kernel.org, linuxppc64-dev@ozlabs.org, linux-kernel@vger.kernel.org List-ID: Alan Cox wrote: > spin_unlock ensures that local CPU writes before the lock are visible > to all processors before the lock is dropped but it has no effect on > I/O ordering. Just a need for clarity. So I can't use spinlocks in my driver to make sure two different CPUs don't interfere with each other when trying to communicate with a device because the spinlocks don't guarantee that I/O operations will stay in effect within the locking section? David