From patchwork Thu May 6 01:57:44 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yunsheng Lin X-Patchwork-Id: 432040 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable 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 DD4A0C43462 for ; Thu, 6 May 2021 01:57:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C238D613BC for ; Thu, 6 May 2021 01:57:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231213AbhEFB6s (ORCPT ); Wed, 5 May 2021 21:58:48 -0400 Received: from szxga05-in.huawei.com ([45.249.212.191]:17465 "EHLO szxga05-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230245AbhEFB6n (ORCPT ); Wed, 5 May 2021 21:58:43 -0400 Received: from DGGEMS406-HUB.china.huawei.com (unknown [172.30.72.58]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4FbGqc5TBczkWpf; Thu, 6 May 2021 09:55:08 +0800 (CST) Received: from localhost.localdomain (10.69.192.56) by DGGEMS406-HUB.china.huawei.com (10.3.19.206) with Microsoft SMTP Server id 14.3.498.0; Thu, 6 May 2021 09:57:38 +0800 From: Yunsheng Lin To: , CC: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , Subject: [PATCH net v5 3/3] net: sched: fix tx action reschedule issue with stopped queue Date: Thu, 6 May 2021 09:57:44 +0800 Message-ID: <1620266264-48109-4-git-send-email-linyunsheng@huawei.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1620266264-48109-1-git-send-email-linyunsheng@huawei.com> References: <1620266264-48109-1-git-send-email-linyunsheng@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.69.192.56] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The netdev qeueue might be stopped when byte queue limit has reached or tx hw ring is full, net_tx_action() may still be rescheduled endlessly if STATE_MISSED is set, which consumes a lot of cpu without dequeuing and transmiting any skb because the netdev queue is stopped, see qdisc_run_end(). This patch fixes it by checking the netdev queue state before calling qdisc_run() and clearing STATE_MISSED if netdev queue is stopped during qdisc_run(), the net_tx_action() is recheduled again when netdev qeueue is restarted, see netif_tx_wake_queue(). As q->enqueue() may return NET_XMIT_DROP when there is no enough space, running qdisc_run() will likely consume unnecessary cpu, so avoid calling qdisc_run() when q->enqueue() returns NET_XMIT_DROP too. Fixes: 6b3ba9146fe6 ("net: sched: allow qdiscs to handle locking") Reported-by: Michal Kubecek Signed-off-by: Yunsheng Lin --- net/core/dev.c | 4 +++- net/sched/sch_generic.c | 8 +++++++- 2 files changed, 10 insertions(+), 2 deletions(-) diff --git a/net/core/dev.c b/net/core/dev.c index d596cd7..005bc3e 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -3853,7 +3853,9 @@ static inline int __dev_xmit_skb(struct sk_buff *skb, struct Qdisc *q, if (q->flags & TCQ_F_NOLOCK) { rc = q->enqueue(skb, q, &to_free) & NET_XMIT_MASK; - qdisc_run(q); + if (likely(rc != NET_XMIT_DROP && + !netif_xmit_frozen_or_stopped(txq))) + qdisc_run(q); if (unlikely(to_free)) kfree_skb_list(to_free); diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c index c32ac5b..2bb829ea 100644 --- a/net/sched/sch_generic.c +++ b/net/sched/sch_generic.c @@ -74,6 +74,7 @@ static inline struct sk_buff *__skb_dequeue_bad_txq(struct Qdisc *q) } } else { skb = SKB_XOFF_MAGIC; + clear_bit(__QDISC_STATE_MISSED, &q->state); } } @@ -242,6 +243,7 @@ static struct sk_buff *dequeue_skb(struct Qdisc *q, bool *validate, } } else { skb = NULL; + clear_bit(__QDISC_STATE_MISSED, &q->state); } if (lock) spin_unlock(lock); @@ -251,8 +253,10 @@ static struct sk_buff *dequeue_skb(struct Qdisc *q, bool *validate, *validate = true; if ((q->flags & TCQ_F_ONETXQUEUE) && - netif_xmit_frozen_or_stopped(txq)) + netif_xmit_frozen_or_stopped(txq)) { + clear_bit(__QDISC_STATE_MISSED, &q->state); return skb; + } skb = qdisc_dequeue_skb_bad_txq(q); if (unlikely(skb)) { @@ -311,6 +315,8 @@ bool sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q, HARD_TX_LOCK(dev, txq, smp_processor_id()); if (!netif_xmit_frozen_or_stopped(txq)) skb = dev_hard_start_xmit(skb, dev, txq, &ret); + else + clear_bit(__QDISC_STATE_MISSED, &q->state); HARD_TX_UNLOCK(dev, txq); } else {