From patchwork Fri Jul 23 07:26:11 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yufeng Mo X-Patchwork-Id: 12395381 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 711F9C4338F for ; Fri, 23 Jul 2021 07:29:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5928A60EFD for ; Fri, 23 Jul 2021 07:29:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233286AbhGWGtW (ORCPT ); Fri, 23 Jul 2021 02:49:22 -0400 Received: from szxga01-in.huawei.com ([45.249.212.187]:7047 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233224AbhGWGtV (ORCPT ); Fri, 23 Jul 2021 02:49:21 -0400 Received: from dggemv703-chm.china.huawei.com (unknown [172.30.72.53]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4GWLR74lyXzYcps; Fri, 23 Jul 2021 15:24:03 +0800 (CST) Received: from dggpeml500024.china.huawei.com (7.185.36.10) by dggemv703-chm.china.huawei.com (10.3.19.46) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Fri, 23 Jul 2021 15:29:53 +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, 23 Jul 2021 15:29:52 +0800 From: Yufeng Mo To: , , , CC: , , , , , , , , , , , Subject: [PATCH RFC net-next] bonding: 3ad: fix the conflict between __bond_release_one and bond_3ad_state_machine_handler Date: Fri, 23 Jul 2021 15:26:11 +0800 Message-ID: <1627025171-18480-1-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: dggems701-chm.china.huawei.com (10.3.19.178) 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 X-Patchwork-State: RFC 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() | | ->ad_rx_machine() | | ->__record_pdu()[step2] | | | | bond_3ad_state_machine_handler() | ->ad_port_selection_logic() | ->try to find free aggregator[step3] | ->try to find suitable aggregator[step4] | ->did not find a suitable aggregator[step5] | | | | bond_3ad_unbind_slave() | 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, the range of bond->mode_lock is extended from only bond_3ad_unbind_slave() to both bond_upper_dev_unlink() and bond_3ad_unbind_slave(). [1]https://lore.kernel.org/netdev/10374.1611947473@famine/ Signed-off-by: Yufeng Mo Acked-by: Jay Vosburgh --- drivers/net/bonding/bond_3ad.c | 7 +------ drivers/net/bonding/bond_main.c | 3 +++ 2 files changed, 4 insertions(+), 6 deletions(-) diff --git a/drivers/net/bonding/bond_3ad.c b/drivers/net/bonding/bond_3ad.c index 6908822..f0f5adb 100644 --- a/drivers/net/bonding/bond_3ad.c +++ b/drivers/net/bonding/bond_3ad.c @@ -2099,15 +2099,13 @@ void bond_3ad_unbind_slave(struct slave *slave) struct list_head *iter; bool dummy_slave_update; /* Ignore this value as caller updates array */ - /* Sync against bond_3ad_state_machine_handler() */ - spin_lock_bh(&bond->mode_lock); aggregator = &(SLAVE_AD_INFO(slave)->aggregator); port = &(SLAVE_AD_INFO(slave)->port); /* if slave is null, the whole port is not initialized */ if (!port->slave) { slave_warn(bond->dev, slave->dev, "Trying to unbind an uninitialized port\n"); - goto out; + return; } slave_dbg(bond->dev, slave->dev, "Unbinding Link Aggregation Group %d\n", @@ -2239,9 +2237,6 @@ void bond_3ad_unbind_slave(struct slave *slave) } } port->slave = NULL; - -out: - spin_unlock_bh(&bond->mode_lock); } /** diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c index 0ff7567..00a501c 100644 --- a/drivers/net/bonding/bond_main.c +++ b/drivers/net/bonding/bond_main.c @@ -2129,6 +2129,8 @@ 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); + /* Sync against bond_3ad_state_machine_handler() */ + spin_lock_bh(&bond->mode_lock); bond_upper_dev_unlink(bond, slave); /* unregister rx_handler early so bond_handle_frame wouldn't be called * for this slave anymore. @@ -2137,6 +2139,7 @@ static int __bond_release_one(struct net_device *bond_dev, if (BOND_MODE(bond) == BOND_MODE_8023AD) bond_3ad_unbind_slave(slave); + spin_unlock_bh(&bond->mode_lock); if (bond_mode_can_use_xmit_hash(bond)) bond_update_slave_arr(bond, slave);