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=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 44C7AC433B4 for ; Mon, 26 Apr 2021 15:22:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 11BF1613A9 for ; Mon, 26 Apr 2021 15:22:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234087AbhDZPXa convert rfc822-to-8bit (ORCPT ); Mon, 26 Apr 2021 11:23:30 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:55586 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234058AbhDZPX3 (ORCPT ); Mon, 26 Apr 2021 11:23:29 -0400 Received: from 1.general.jvosburgh.us.vpn ([10.172.68.206] helo=famine.localdomain) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1lb34L-0006HG-0u; Mon, 26 Apr 2021 15:22:41 +0000 Received: by famine.localdomain (Postfix, from userid 1000) id 9A1AF5FDD5; Mon, 26 Apr 2021 08:22:37 -0700 (PDT) Received: from famine (localhost [127.0.0.1]) by famine.localdomain (Postfix) with ESMTP id 930239FC56; Mon, 26 Apr 2021 08:22:37 -0700 (PDT) From: Jay Vosburgh To: David Miller cc: jinyiting@huawei.com, vfalico@gmail.com, andy@greyhouse.net, kuba@kernel.org, netdev@vger.kernel.org, security@kernel.org, linux-kernel@vger.kernel.org, xuhanbing@huawei.com, wangxiaogang3@huawei.com Subject: Re: [PATCH] bonding: 3ad: Fix the conflict between bond_update_slave_arr and the state machine In-reply-to: <20210423.130748.1071901004935481894.davem@davemloft.net> References: <1618994301-1186-1-git-send-email-jinyiting@huawei.com> <20210423.130748.1071901004935481894.davem@davemloft.net> Comments: In-reply-to David Miller message dated "Fri, 23 Apr 2021 13:07:48 -0700." X-Mailer: MH-E 8.6+git; nmh 1.6; GNU Emacs 27.0.50 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT Date: Mon, 26 Apr 2021 08:22:37 -0700 Message-ID: <20034.1619450557@famine> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org David Miller wrote: >From: jinyiting >Date: Wed, 21 Apr 2021 16:38:21 +0800 > >> The bond works in mode 4, and performs down/up operations on the bond >> that is normally negotiated. The probability of bond-> slave_arr is NULL >> >> Test commands: >> ifconfig bond1 down >> ifconfig bond1 up >> >> The conflict occurs in the following process： >> >> __dev_open (CPU A) >> --bond_open >> --queue_delayed_work(bond->wq,&bond->ad_work,0); >> --bond_update_slave_arr >> --bond_3ad_get_active_agg_info >> >> ad_work(CPU B) >> --bond_3ad_state_machine_handler >> --ad_agg_selection_logic >> >> ad_work runs on cpu B. In the function ad_agg_selection_logic, all >> agg->is_active will be cleared. Before the new active aggregator is >> selected on CPU B, bond_3ad_get_active_agg_info failed on CPU A, >> bond->slave_arr will be set to NULL. The best aggregator in >> ad_agg_selection_logic has not changed, no need to update slave arr. >> >> The conflict occurred in that ad_agg_selection_logic clears >> agg->is_active under mode_lock, but bond_open -> bond_update_slave_arr >> is inspecting agg->is_active outside the lock. >> >> Also, bond_update_slave_arr is normal for potential sleep when >> allocating memory, so replace the WARN_ON with a call to might_sleep. >> >> Signed-off-by: jinyiting >> --- >> >> Previous versions: >> * https://lore.kernel.org/netdev/612b5e32-ea11-428e-0c17-e2977185f045@huawei.com/ >> >> drivers/net/bonding/bond_main.c | 7 ++++--- >> 1 file changed, 4 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c >> index 74cbbb2..83ef62d 100644 >> --- a/drivers/net/bonding/bond_main.c >> +++ b/drivers/net/bonding/bond_main.c >> @@ -4406,7 +4404,9 @@ int bond_update_slave_arr(struct bonding *bond, struct slave *skipslave) >> if (BOND_MODE(bond) == BOND_MODE_8023AD) { >> struct ad_info ad_info; >> >> + spin_lock_bh(&bond->mode_lock); > >The code paths that call this function with mode_lock held will now deadlock. No path should be calling bond_update_slave_arr with mode_lock already held (it expects RTNL only); did you find one? My concern is that there's something else that does the opposite order, i.e., mode_lock first, then RTNL, but I haven't found an example. -J --- -Jay Vosburgh, jay.vosburgh@canonical.com