From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ding Tianhong Subject: [PATCH net-next v2 3/5] bonding: remove bond read lock for bond_loadbalance_arp_mon() Date: Thu, 24 Oct 2013 11:09:17 +0800 Message-ID: <52688F5D.1010400@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit To: Jay Vosburgh , Andy Gospodarek , "David S. Miller" , Nikolay Aleksandrov , Veaceslav Falico , Netdev Return-path: Received: from szxga02-in.huawei.com ([119.145.14.65]:39660 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753719Ab3JXDMM (ORCPT ); Wed, 23 Oct 2013 23:12:12 -0400 Sender: netdev-owner@vger.kernel.org List-ID: The bond slave list may change when the monitor is running, the slave list is no longer protected by bond->lock, only protected by rtnl lock(), so we has 3 way to modify it: 1.add bond_master_upper_dev_link() and bond_upper_dev_unlink() in bond->lock, but it is unsafe to call call_netdevice_notifiers() in write lock. 2.remove unused bond->lock for monitor function, only use the exist rtnl lock(). 3.use rcu_read_lock() to protect it, of course, it will transform bond_for_each_slave to bond_for_each_slave_rcu() and performance is better, but in slow path, it is ignored. so I remove the bond->lock and add the rtnl lock to protect the whole monitor function. Signed-off-by: Ding Tianhong --- drivers/net/bonding/bond_main.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c index ba90f45..149f4b9 100644 --- a/drivers/net/bonding/bond_main.c +++ b/drivers/net/bonding/bond_main.c @@ -2433,10 +2433,13 @@ void bond_loadbalance_arp_mon(struct work_struct *work) struct list_head *iter; int do_failover = 0; - read_lock(&bond->lock); + if (!rtnl_trylock()) + goto re_arm; - if (!bond_has_slaves(bond)) + if (!bond_has_slaves(bond)) { + rtnl_unlock(); goto re_arm; + } oldcurrent = bond->curr_active_slave; /* see if any of the previous devices are up now (i.e. they have @@ -2518,13 +2521,12 @@ void bond_loadbalance_arp_mon(struct work_struct *work) write_unlock_bh(&bond->curr_slave_lock); unblock_netpoll_tx(); } + rtnl_unlock(); re_arm: if (bond->params.arp_interval) queue_delayed_work(bond->wq, &bond->arp_work, msecs_to_jiffies(bond->params.arp_interval)); - - read_unlock(&bond->lock); } /* -- 1.8.2.1