From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8877CC433DF for ; Sun, 2 Aug 2020 03:42:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 610CD2072A for ; Sun, 2 Aug 2020 03:42:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727779AbgHBDlv (ORCPT ); Sat, 1 Aug 2020 23:41:51 -0400 Received: from out30-56.freemail.mail.aliyun.com ([115.124.30.56]:53699 "EHLO out30-56.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725883AbgHBDlu (ORCPT ); Sat, 1 Aug 2020 23:41:50 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R131e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04394;MF=wenan.mao@linux.alibaba.com;NM=1;PH=DS;RN=6;SR=0;TI=SMTPD_---0U4S33z6_1596339685; Received: from VM20200710-3.tbsite.net(mailfrom:wenan.mao@linux.alibaba.com fp:SMTPD_---0U4S33z6_1596339685) by smtp.aliyun-inc.com(127.0.0.1); Sun, 02 Aug 2020 11:41:37 +0800 From: Mao Wenan To: mst@redhat.com, jasowang@redhat.com, davem@davemloft.net, kuba@kernel.org Cc: netdev@vger.kernel.org, Mao Wenan Subject: [PATCH -next] virtio_net: Avoid loop in virtnet_poll Date: Sun, 2 Aug 2020 11:41:23 +0800 Message-Id: <1596339683-117617-1-git-send-email-wenan.mao@linux.alibaba.com> X-Mailer: git-send-email 1.8.3.1 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The loop may exist if vq->broken is true, virtqueue_get_buf_ctx_packed or virtqueue_get_buf_ctx_split will return NULL, so virtnet_poll will reschedule napi to receive packet, it will lead cpu usage(si) to 100%. call trace as below: virtnet_poll virtnet_receive virtqueue_get_buf_ctx virtqueue_get_buf_ctx_packed virtqueue_get_buf_ctx_split virtqueue_napi_complete virtqueue_napi_schedule //it will reschedule napi Signed-off-by: Mao Wenan --- drivers/net/virtio_net.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index ba38765..a058da1 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -327,7 +327,8 @@ static void virtqueue_napi_complete(struct napi_struct *napi, opaque = virtqueue_enable_cb_prepare(vq); if (napi_complete_done(napi, processed)) { - if (unlikely(virtqueue_poll(vq, opaque))) + if (unlikely(virtqueue_poll(vq, opaque)) && + unlikely(!virtqueue_is_broken(vq))) virtqueue_napi_schedule(napi, vq); } else { virtqueue_disable_cb(vq); -- 1.8.3.1