From patchwork Fri Jun 28 01:13:19 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yunsheng Lin X-Patchwork-Id: 11020911 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 68AAD14E5 for ; Fri, 28 Jun 2019 01:14:47 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4D89928758 for ; Fri, 28 Jun 2019 01:14:47 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 3D9A828762; Fri, 28 Jun 2019 01:14:47 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 9151628758 for ; Fri, 28 Jun 2019 01:14:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726657AbfF1BOl (ORCPT ); Thu, 27 Jun 2019 21:14:41 -0400 Received: from szxga07-in.huawei.com ([45.249.212.35]:52498 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726605AbfF1BOl (ORCPT ); Thu, 27 Jun 2019 21:14:41 -0400 Received: from DGGEMS410-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id D1238800C514BC90051C; Fri, 28 Jun 2019 09:14:38 +0800 (CST) Received: from localhost.localdomain (10.67.212.75) by DGGEMS410-HUB.china.huawei.com (10.3.19.210) with Microsoft SMTP Server id 14.3.439.0; Fri, 28 Jun 2019 09:14:35 +0800 From: Yunsheng Lin To: CC: , , , , , , , Subject: [PATCH v3 net-next] net: link_watch: prevent starvation when processing linkwatch wq Date: Fri, 28 Jun 2019 09:13:19 +0800 Message-ID: <1561684399-235123-1-git-send-email-linyunsheng@huawei.com> X-Mailer: git-send-email 2.8.1 MIME-Version: 1.0 X-Originating-IP: [10.67.212.75] X-CFilter-Loop: Reflected Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP When user has configured a large number of virtual netdev, such as 4K vlans, the carrier on/off operation of the real netdev will also cause it's virtual netdev's link state to be processed in linkwatch. Currently, the processing is done in a work queue, which may cause rtnl locking starvation problem and worker starvation problem for other work queue, such as irqfd_inject wq. This patch releases the cpu when link watch worker has processed a fixed number of netdev' link watch event, and schedule the work queue again when there is still link watch event remaining. Signed-off-by: Yunsheng Lin --- V2: use cond_resched and rtnl_unlock after processing a fixed number of events V3: fall back to v1 and change commit log to reflect that. --- --- net/core/link_watch.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/net/core/link_watch.c b/net/core/link_watch.c index 04fdc95..f153e06 100644 --- a/net/core/link_watch.c +++ b/net/core/link_watch.c @@ -163,9 +163,16 @@ static void linkwatch_do_dev(struct net_device *dev) static void __linkwatch_run_queue(int urgent_only) { +#define MAX_DO_DEV_PER_LOOP 100 + + int do_dev = MAX_DO_DEV_PER_LOOP; struct net_device *dev; LIST_HEAD(wrk); + /* Give urgent case more budget */ + if (urgent_only) + do_dev += MAX_DO_DEV_PER_LOOP; + /* * Limit the number of linkwatch events to one * per second so that a runaway driver does not @@ -184,7 +191,7 @@ static void __linkwatch_run_queue(int urgent_only) spin_lock_irq(&lweventlist_lock); list_splice_init(&lweventlist, &wrk); - while (!list_empty(&wrk)) { + while (!list_empty(&wrk) && do_dev > 0) { dev = list_first_entry(&wrk, struct net_device, link_watch_list); list_del_init(&dev->link_watch_list); @@ -195,9 +202,13 @@ static void __linkwatch_run_queue(int urgent_only) } spin_unlock_irq(&lweventlist_lock); linkwatch_do_dev(dev); + do_dev--; spin_lock_irq(&lweventlist_lock); } + /* Add the remaining work back to lweventlist */ + list_splice_init(&wrk, &lweventlist); + if (!list_empty(&lweventlist)) linkwatch_schedule_work(0); spin_unlock_irq(&lweventlist_lock);