From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ding Tianhong Subject: [PATCH net-next v2 4/10] bonding: rebuild the lock use for bond_loadbalance_arp_mon() Date: Fri, 8 Nov 2013 10:07:56 +0800 Message-ID: <527C477C.9050008@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]:1763 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753806Ab3KHCI1 (ORCPT ); Thu, 7 Nov 2013 21:08:27 -0500 Sender: netdev-owner@vger.kernel.org List-ID: The bond_loadbalance_arp_mon() use the bond lock to protect the bond slave list, it is no effect, so I could use RTNL or RCU to replace it, considering the performance impact, the RCU is more better here, so the bond lock replace with the RCU. The bond_select_active_slave() need RTNL and curr_slave_lock together, but there is no RTNL lock here, so add a rtnl_rtylock. Suggested-by: Jay Vosburgh Suggested-by: Veaceslav Falico Signed-off-by: Ding Tianhong --- drivers/net/bonding/bond_main.c | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-) diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c index def489d..759dcd0 100644 --- a/drivers/net/bonding/bond_main.c +++ b/drivers/net/bonding/bond_main.c @@ -2407,12 +2407,14 @@ void bond_loadbalance_arp_mon(struct work_struct *work) struct list_head *iter; int do_failover = 0; - read_lock(&bond->lock); + rcu_read_lock(); - if (!bond_has_slaves(bond)) + if (!bond_has_slaves_rcu(bond)) { + rcu_read_unlock(); goto re_arm; + } - oldcurrent = bond->curr_active_slave; + oldcurrent = ACCESS_ONCE(bond->curr_active_slave); /* see if any of the previous devices are up now (i.e. they have * xmt and rcv traffic). the curr_active_slave does not come into * the picture unless it is null. also, slave->jiffies is not needed @@ -2421,7 +2423,7 @@ void bond_loadbalance_arp_mon(struct work_struct *work) * TODO: what about up/down delay in arp mode? it wasn't here before * so it can wait */ - bond_for_each_slave(bond, slave, iter) { + bond_for_each_slave_rcu(bond, slave, iter) { unsigned long trans_start = dev_trans_start(slave->dev); if (slave->link != BOND_LINK_UP) { @@ -2483,7 +2485,14 @@ void bond_loadbalance_arp_mon(struct work_struct *work) bond_arp_send_all(bond, slave); } + rcu_read_unlock(); + if (do_failover) { + /* the bond_select_active_slave must hold RTNL + * and curr_slave_lock for write. + */ + if (!rtnl_trylock()) + goto re_arm; block_netpoll_tx(); write_lock_bh(&bond->curr_slave_lock); @@ -2491,14 +2500,13 @@ 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