Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S967076AbbLQPJZ (ORCPT ); Thu, 17 Dec 2015 10:09:25 -0500 Received: from bombadil.infradead.org ([198.137.202.9]:50680 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964850AbbLQPJY (ORCPT ); Thu, 17 Dec 2015 10:09:24 -0500 Date: Thu, 17 Dec 2015 16:09:17 +0100 From: Peter Zijlstra To: "Michael S. Tsirkin" Cc: linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Jason Wang , qemu-devel@nongnu.org, Alexander Duyck , Will Deacon Subject: Re: [PATCH] virtio_ring: use smp_store_mb Message-ID: <20151217150917.GP6373@twins.programming.kicks-ass.net> References: <1450347932-16325-1-git-send-email-mst@redhat.com> <20151217112222.GC6375@twins.programming.kicks-ass.net> <20151217151705-mutt-send-email-mst@redhat.com> <20151217140212.GB6344@twins.programming.kicks-ass.net> <20151217163412-mutt-send-email-mst@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20151217163412-mutt-send-email-mst@redhat.com> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1039 Lines: 26 On Thu, Dec 17, 2015 at 04:34:57PM +0200, Michael S. Tsirkin wrote: > On Thu, Dec 17, 2015 at 03:02:12PM +0100, Peter Zijlstra wrote: > > > commit 9e1a27ea42691429e31f158cce6fc61bc79bb2e9 > > > Author: Alexander Duyck > > > Date: Mon Apr 13 21:03:49 2015 +0930 > > > > > > virtio_ring: Update weak barriers to use dma_wmb/rmb > > > > That commit doesn't make any sense. dma_*mb() explicitly does _NOT_ > > cover the smp_*mb() part. > > > > Again, look at the ARM definitions, the smp_*mb() primitives use the > > inner coherence stuff, while the dma_*mb() primitives use the outer > > coherent stuff. > > Does outer coherent imply inner coherent? > > > the *mb() primitives cover both. I do not think so, but lets add Will, he dreams this stuff. -- 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/