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 1C442C433B4 for ; Mon, 26 Apr 2021 19:10:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E346560FE8 for ; Mon, 26 Apr 2021 19:10:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240277AbhDZTJZ (ORCPT ); Mon, 26 Apr 2021 15:09:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53278 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240229AbhDZTJK (ORCPT ); Mon, 26 Apr 2021 15:09:10 -0400 Received: from mail.monkeyblade.net (shards.monkeyblade.net [IPv6:2620:137:e000::1:9]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 98F8FC061574; Mon, 26 Apr 2021 12:08:28 -0700 (PDT) Received: from localhost (unknown [IPv6:2601:601:9f00:477::3d5]) by mail.monkeyblade.net (Postfix) with ESMTPSA id 99DD74F21C303; Mon, 26 Apr 2021 12:08:26 -0700 (PDT) Date: Mon, 26 Apr 2021 12:08:22 -0700 (PDT) Message-Id: <20210426.120822.232032630973964712.davem@davemloft.net> To: jay.vosburgh@canonical.com 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 From: David Miller In-Reply-To: <20034.1619450557@famine> References: <1618994301-1186-1-git-send-email-jinyiting@huawei.com> <20210423.130748.1071901004935481894.davem@davemloft.net> <20034.1619450557@famine> X-Mailer: Mew version 6.8 on Emacs 27.1 Mime-Version: 1.0 Content-Type: Text/Plain; charset=iso-2022-jp Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.6.2 (mail.monkeyblade.net [0.0.0.0]); Mon, 26 Apr 2021 12:08:27 -0700 (PDT) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jay Vosburgh Date: Mon, 26 Apr 2021 08:22:37 -0700 > 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. > This patch is removing a lockdep assertion masking sure that mode_lock was held when this function was called. That should have been triggering all the time, right? Thanks.