From patchwork Fri Jul 30 02:19:11 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yufeng Mo X-Patchwork-Id: 12410219 X-Patchwork-Delegate: kuba@kernel.org 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=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 AC9DEC4338F for ; Fri, 30 Jul 2021 02:23:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8C2AD61019 for ; Fri, 30 Jul 2021 02:23:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235727AbhG3CXK (ORCPT ); Thu, 29 Jul 2021 22:23:10 -0400 Received: from szxga02-in.huawei.com ([45.249.212.188]:7900 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230200AbhG3CXJ (ORCPT ); Thu, 29 Jul 2021 22:23:09 -0400 Received: from dggemv704-chm.china.huawei.com (unknown [172.30.72.54]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4GbWLD65dHz81Z0; Fri, 30 Jul 2021 10:19:16 +0800 (CST) Received: from dggpeml500024.china.huawei.com (7.185.36.10) by dggemv704-chm.china.huawei.com (10.3.19.47) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Fri, 30 Jul 2021 10:22:53 +0800 Received: from localhost.localdomain (10.67.165.24) by dggpeml500024.china.huawei.com (7.185.36.10) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Fri, 30 Jul 2021 10:22:53 +0800 From: Yufeng Mo To: , , , CC: , , , , , , , , , , , Subject: [PATCH V2 net-next] bonding: 3ad: fix the concurrency between __bond_release_one() and bond_3ad_state_machine_handler() Date: Fri, 30 Jul 2021 10:19:11 +0800 Message-ID: <1627611551-33333-1-git-send-email-moyufeng@huawei.com> X-Mailer: git-send-email 2.8.1 MIME-Version: 1.0 X-Originating-IP: [10.67.165.24] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To dggpeml500024.china.huawei.com (7.185.36.10) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org Some time ago, I reported a calltrace issue "did not find a suitable aggregator", please see[1]. After a period of analysis and reproduction, I find that this problem is caused by concurrency. Before the problem occurs, the bond structure is like follows: bond0 - slaver0(eth0) - agg0.lag_ports -> port0 - port1 \ port0 \ slaver1(eth1) - agg1.lag_ports -> NULL \ port1 If we run 'ifenslave bond0 -d eth1', the process is like below: excuting __bond_release_one() | bond_upper_dev_unlink()[step1] | | | | | bond_3ad_lacpdu_recv() | | ->bond_3ad_rx_indication() | | spin_lock_bh() | | ->ad_rx_machine() | | ->__record_pdu()[step2] | | spin_unlock_bh() | | | | bond_3ad_state_machine_handler() | spin_lock_bh() | ->ad_port_selection_logic() | ->try to find free aggregator[step3] | ->try to find suitable aggregator[step4] | ->did not find a suitable aggregator[step5] | spin_unlock_bh() | | | | bond_3ad_unbind_slave() | spin_lock_bh() spin_unlock_bh() step1: already removed slaver1(eth1) from list, but port1 remains step2: receive a lacpdu and update port0 step3: port0 will be removed from agg0.lag_ports. The struct is "agg0.lag_ports -> port1" now, and agg0 is not free. At the same time, slaver1/agg1 has been removed from the list by step1. So we can't find a free aggregator now. step4: can't find suitable aggregator because of step2 step5: cause a calltrace since port->aggregator is NULL To solve this concurrency problem, put bond_upper_dev_unlink() after bond_3ad_unbind_slave(). In this way, we can invalid the port first and skip this port in bond_3ad_state_machine_handler(). This eliminates the situation that the slaver has been removed from the list but the port is still valid. [1]https://lore.kernel.org/netdev/10374.1611947473@famine/ Signed-off-by: Yufeng Mo Acked-by: Jay Vosburgh --- ChangeLogs: V1 -> V2: Modify the method of resolving concurrency because bond_upper_dev_unlink() may sleep and cannot hold mode lock. --- drivers/net/bonding/bond_main.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c index d22d783..c23f39e 100644 --- a/drivers/net/bonding/bond_main.c +++ b/drivers/net/bonding/bond_main.c @@ -2252,7 +2252,6 @@ static int __bond_release_one(struct net_device *bond_dev, /* recompute stats just before removing the slave */ bond_get_stats(bond->dev, &bond->bond_stats); - bond_upper_dev_unlink(bond, slave); /* unregister rx_handler early so bond_handle_frame wouldn't be called * for this slave anymore. */ @@ -2261,6 +2260,8 @@ static int __bond_release_one(struct net_device *bond_dev, if (BOND_MODE(bond) == BOND_MODE_8023AD) bond_3ad_unbind_slave(slave); + bond_upper_dev_unlink(bond, slave); + if (bond_mode_can_use_xmit_hash(bond)) bond_update_slave_arr(bond, slave);