From patchwork Thu Dec 29 10:43:15 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Rusty Russell X-Patchwork-Id: 133537 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 F3AD1B6F9B for ; Thu, 29 Dec 2011 21:44:51 +1100 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752839Ab1L2Koo (ORCPT ); Thu, 29 Dec 2011 05:44:44 -0500 Received: from ozlabs.org ([203.10.76.45]:38216 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752696Ab1L2Koo (ORCPT ); Thu, 29 Dec 2011 05:44:44 -0500 Received: by ozlabs.org (Postfix, from userid 1011) id 44443B6FC4; Thu, 29 Dec 2011 21:44:43 +1100 (EST) From: Rusty Russell To: netdev Cc: "Michael S. Tsirkin" , Tejun Heo Subject: [PATCH] virtio_net: use non-reentrant workqueue. References: <87ehvogitg.fsf@rustcorp.com.au> User-Agent: Notmuch/0.6.1-1 (http://notmuchmail.org) Emacs/23.3.1 (i686-pc-linux-gnu) Date: Thu, 29 Dec 2011 21:13:15 +1030 Message-ID: <87mxabfykc.fsf@rustcorp.com.au> MIME-Version: 1.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Michael S. Tsirkin also noticed that we could run the refill work multiple CPUs: if we kick off a refill on one CPU and then on another, they would both manipulate the queue at the same time (they use napi_disable to avoid racing against the receive handler itself). Tejun points out that this is what the WQ_NON_REENTRANT flag is for, and that there is a convenient system kthread we can use. Signed-off-by: Rusty Russell --- drivers/net/virtio_net.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -507,7 +507,7 @@ static void refill_work(struct work_stru /* In theory, this can happen: if we don't get any buffers in * we will *never* try to fill again. */ if (still_empty) - schedule_delayed_work(&vi->refill, HZ/2); + queue_delayed_work(system_nrt_wq, &vi->refill, HZ/2); } static int virtnet_poll(struct napi_struct *napi, int budget) @@ -526,7 +526,7 @@ again: if (vi->num < vi->max / 2) { if (!try_fill_recv(vi, GFP_ATOMIC)) - schedule_delayed_work(&vi->refill, 0); + queue_delayed_work(system_nrt_wq, &vi->refill, 0); } /* Out of packets? */ @@ -727,7 +727,7 @@ static int virtnet_open(struct net_devic /* Make sure we have some buffers: if oom use wq. */ if (!try_fill_recv(vi, GFP_KERNEL)) - schedule_delayed_work(&vi->refill, 0); + queue_delayed_work(system_nrt_wq, &vi->refill, 0); virtnet_napi_enable(vi); return 0;