From patchwork Fri Aug 30 04:29:21 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jason Wang X-Patchwork-Id: 271099 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 2FF0E2C008E for ; Fri, 30 Aug 2013 14:42:23 +1000 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756189Ab3H3Elf (ORCPT ); Fri, 30 Aug 2013 00:41:35 -0400 Received: from mx1.redhat.com ([209.132.183.28]:11923 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755803Ab3H3ElY (ORCPT ); Fri, 30 Aug 2013 00:41:24 -0400 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r7U4fLHA005467 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Fri, 30 Aug 2013 00:41:21 -0400 Received: from amd-6168-8-1.englab.nay.redhat.com (amd-6168-8-1.englab.nay.redhat.com [10.66.104.52]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id r7U4ev01013964; Fri, 30 Aug 2013 00:41:18 -0400 From: Jason Wang To: mst@redhat.com, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Jason Wang Subject: [PATCH V2 5/6] vhost_net: poll vhost queue after marking DMA is done Date: Fri, 30 Aug 2013 12:29:21 +0800 Message-Id: <1377836962-49780-6-git-send-email-jasowang@redhat.com> In-Reply-To: <1377836962-49780-1-git-send-email-jasowang@redhat.com> References: <1377836962-49780-1-git-send-email-jasowang@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.24 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org We used to poll vhost queue before making DMA is done, this is racy if vhost thread were waked up before marking DMA is done which can result the signal to be missed. Fix this by always poll the vhost thread before DMA is done. Signed-off-by: Jason Wang --- drivers/vhost/net.c | 9 +++++---- 1 files changed, 5 insertions(+), 4 deletions(-) diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index ff60c2a..d09c17c 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -308,6 +308,11 @@ static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success) struct vhost_virtqueue *vq = ubufs->vq; int cnt = atomic_read(&ubufs->kref.refcount); + /* set len to mark this desc buffers done DMA */ + vq->heads[ubuf->desc].len = success ? + VHOST_DMA_DONE_LEN : VHOST_DMA_FAILED_LEN; + vhost_net_ubuf_put(ubufs); + /* * Trigger polling thread if guest stopped submitting new buffers: * in this case, the refcount after decrement will eventually reach 1 @@ -318,10 +323,6 @@ static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success) */ if (cnt <= 2 || !(cnt % 16)) vhost_poll_queue(&vq->poll); - /* set len to mark this desc buffers done DMA */ - vq->heads[ubuf->desc].len = success ? - VHOST_DMA_DONE_LEN : VHOST_DMA_FAILED_LEN; - vhost_net_ubuf_put(ubufs); } /* Expects to be always run from workqueue - which acts as