From patchwork Fri Jan 10 10:59:44 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Veaceslav Falico X-Patchwork-Id: 309254 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 8FD282C00A8 for ; Fri, 10 Jan 2014 22:04:17 +1100 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757287AbaAJLEN (ORCPT ); Fri, 10 Jan 2014 06:04:13 -0500 Received: from mx1.redhat.com ([209.132.183.28]:34611 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756705AbaAJLEE (ORCPT ); Fri, 10 Jan 2014 06:04:04 -0500 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s0AB40TE011376 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Fri, 10 Jan 2014 06:04:00 -0500 Received: from darkmag.usersys.redhat.com (dhcp-27-102.brq.redhat.com [10.34.27.102]) by int-mx01.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id s0AB3tf6026212; Fri, 10 Jan 2014 06:03:58 -0500 From: Veaceslav Falico To: netdev@vger.kernel.org Cc: Veaceslav Falico , dingtianhong@huawei.com, Jay Vosburgh , Andy Gospodarek Subject: [PATCH v4 net-next 2/3] bonding: fix __get_first_agg RCU usage Date: Fri, 10 Jan 2014 11:59:44 +0100 Message-Id: <1389351585-19615-3-git-send-email-vfalico@redhat.com> In-Reply-To: <1389351585-19615-1-git-send-email-vfalico@redhat.com> References: <1389351585-19615-1-git-send-email-vfalico@redhat.com> X-Scanned-By: MIMEDefang 2.67 on 10.5.11.11 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Currently, the RCU read lock usage is just wrong - it gets the slave struct under RCU and continues to use it when RCU lock is released. However, it's still safe to do this cause we didn't need the rcu_read_lock() initially - all of the __get_first_agg() callers are either holding RCU read lock or the RTNL lock, so that we can't sync while in it. Fixes: be79bd048 ("bonding: add RCU for bond_3ad_state_machine_handler()") CC: dingtianhong@huawei.com CC: Jay Vosburgh CC: Andy Gospodarek Signed-off-by: Veaceslav Falico --- Notes: v3 -> v4: add rcu_read_lock() to silence lockdep. v2 -> v3: Use the rcu primitives. v1 -> v2: Don't use RCU primitives as we can hold RTNL. drivers/net/bonding/bond_3ad.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/net/bonding/bond_3ad.c b/drivers/net/bonding/bond_3ad.c index da0d7c5..b49f421 100644 --- a/drivers/net/bonding/bond_3ad.c +++ b/drivers/net/bonding/bond_3ad.c @@ -143,11 +143,13 @@ static inline struct bonding *__get_bond_by_port(struct port *port) * * Return the aggregator of the first slave in @bond, or %NULL if it can't be * found. + * The caller must hold RCU or RTNL lock. */ static inline struct aggregator *__get_first_agg(struct port *port) { struct bonding *bond = __get_bond_by_port(port); struct slave *first_slave; + struct aggregator *agg; /* If there's no bond for this port, or bond has no slaves */ if (bond == NULL) @@ -155,9 +157,10 @@ static inline struct aggregator *__get_first_agg(struct port *port) rcu_read_lock(); first_slave = bond_first_slave_rcu(bond); + agg = first_slave ? &(SLAVE_AD_INFO(first_slave).aggregator) : NULL; rcu_read_unlock(); - return first_slave ? &(SLAVE_AD_INFO(first_slave).aggregator) : NULL; + return agg; } /**