From patchwork Thu Jan 14 11:55:06 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ivan Vecera X-Patchwork-Id: 12019355 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=-16.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 AD926C433DB for ; Thu, 14 Jan 2021 11:56:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6DBA42310E for ; Thu, 14 Jan 2021 11:56:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728252AbhANL4i (ORCPT ); Thu, 14 Jan 2021 06:56:38 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:37464 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726376AbhANL4i (ORCPT ); Thu, 14 Jan 2021 06:56:38 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1610625311; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=DlZ5F5E1ivwqXZEXGI43ZKr4tUgsk7s+d0KLqvxzOB4=; b=bEkNIqTkpg1xJb+Y8ExCMfHA3XqeoH9jCXdSbQQgeDh6gzTvBN9ol7pPwaOT15me6FS5fg bneUUdOJIqa7rxl+g6xAA9Izk87hb0EXUYVJZ/mQKMskgJ1O+yMXCIMZ4ZSJ15bYZH/Ate a6zDq5QMcV0D+GORbx5DE6JMe7SM+6o= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-588-tQeAeZtZN6mEoNlbbSHbhA-1; Thu, 14 Jan 2021 06:55:09 -0500 X-MC-Unique: tQeAeZtZN6mEoNlbbSHbhA-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 69AD3806675; Thu, 14 Jan 2021 11:55:08 +0000 (UTC) Received: from ceranb.redhat.com (unknown [10.40.195.230]) by smtp.corp.redhat.com (Postfix) with ESMTP id 3EC305D9E2; Thu, 14 Jan 2021 11:55:07 +0000 (UTC) From: Ivan Vecera To: netdev@vger.kernel.org Cc: Jiri Pirko Subject: [PATCH net] team: fix deadlock during setting of MTU Date: Thu, 14 Jan 2021 12:55:06 +0100 Message-Id: <20210114115506.1713330-1-ivecera@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org Team driver protects port list traversal in team_change_mtu() by its team->lock mutex. This causes a deadlock with certain devices that calls netdev_update_features() during their .ndo_change_mtu() callback. In this case netdev_update_features() calls team's netdevice notifier team_device_event() that in case of NETDEV_FEAT_CHANGE tries lock team->lock mutex again. Example (r8169 case): ... [ 6391.348202] __mutex_lock.isra.6+0x2d0/0x4a0 [ 6391.358602] team_device_event+0x9d/0x160 [team] [ 6391.363756] notifier_call_chain+0x47/0x70 [ 6391.368329] netdev_update_features+0x56/0x60 [ 6391.373207] rtl8169_change_mtu+0x14/0x50 [r8169] [ 6391.378457] dev_set_mtu_ext+0xe1/0x1d0 [ 6391.387022] dev_set_mtu+0x52/0x90 [ 6391.390820] team_change_mtu+0x64/0xf0 [team] [ 6391.395683] dev_set_mtu_ext+0xe1/0x1d0 [ 6391.399963] do_setlink+0x231/0xf50 ... To fix the problem the port list traversal in team_change_mtu() can be protected by RCU read lock. In case of failure the failing port is marked and unwind code-path is done also under RCU read lock protection (but not in reverse order). Fixes: 3d249d4ca7d0 ("net: introduce ethernet teaming device") Cc: Jiri Pirko Signed-off-by: Ivan Vecera --- drivers/net/team/team.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) diff --git a/drivers/net/team/team.c b/drivers/net/team/team.c index c19dac21c468..69d4b28beb17 100644 --- a/drivers/net/team/team.c +++ b/drivers/net/team/team.c @@ -1802,35 +1802,35 @@ static int team_set_mac_address(struct net_device *dev, void *p) static int team_change_mtu(struct net_device *dev, int new_mtu) { struct team *team = netdev_priv(dev); - struct team_port *port; + struct team_port *port, *fail_port; int err; - /* - * Alhough this is reader, it's guarded by team lock. It's not possible - * to traverse list in reverse under rcu_read_lock - */ - mutex_lock(&team->lock); + rcu_read_lock(); team->port_mtu_change_allowed = true; - list_for_each_entry(port, &team->port_list, list) { + list_for_each_entry_rcu(port, &team->port_list, list) { err = dev_set_mtu(port->dev, new_mtu); if (err) { netdev_err(dev, "Device %s failed to change mtu", port->dev->name); + fail_port = port; goto unwind; } } team->port_mtu_change_allowed = false; - mutex_unlock(&team->lock); + rcu_read_unlock(); dev->mtu = new_mtu; return 0; unwind: - list_for_each_entry_continue_reverse(port, &team->port_list, list) + list_for_each_entry_rcu(port, &team->port_list, list) { + if (port == fail_port) + break; dev_set_mtu(port->dev, dev->mtu); + } team->port_mtu_change_allowed = false; - mutex_unlock(&team->lock); + rcu_read_unlock(); return err; }