From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH 3/3] kvm-s390: streamline memslot handling - rebased Date: Mon, 08 Jun 2009 14:10:26 +0300 Message-ID: <4A2CF1A2.8090904@redhat.com> References: <1243952771-32428-1-git-send-email-ehrhardt@linux.vnet.ibm.com> <1243952771-32428-4-git-send-email-ehrhardt@linux.vnet.ibm.com> <20090605205312.GA13471@amt.cnet> <4A2CED2E.6030904@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Marcelo Tosatti , kvm@vger.kernel.org, borntraeger@de.ibm.com, cotte@de.ibm.com, heiko.carstens@de.ibm.com, schwidefsky@de.ibm.com To: Christian Ehrhardt Return-path: Received: from mx2.redhat.com ([66.187.237.31]:56134 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754193AbZFHLK2 (ORCPT ); Mon, 8 Jun 2009 07:10:28 -0400 In-Reply-To: <4A2CED2E.6030904@linux.vnet.ibm.com> Sender: kvm-owner@vger.kernel.org List-ID: Christian Ehrhardt wrote: >> >> Really need that smp_mb__after_clear_bit ? AFAIK test_and_clear_bit >> implies a barrier? >> > > Well I agree that practically test_and_clear_bit has a barrier on > s390, but as far as I read Documentation/atomic_ops.txt at line > 339-360 I think the interface does not imply it so I wanted to add it > explicitly. I would be happy if someone really knows the in depth > details here and corrects me :-) IIUC rmw bitops are full memory barriers. The non-rmw (from the caller's perspective), clear_bit() and set_bit(), are not. -- error compiling committee.c: too many arguments to function