From 80b9d236ec56ecc18da4a43bd79e8ec9ac5036ff Mon Sep 17 00:00:00 2001 From: dingtianhong Date: Thu, 24 Oct 2013 11:09:25 +0800 Subject: [PATCH] bonding: remove bond read lock for bond_activebackup_arp_mon() 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 have 3 ways 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 existing 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 move the rtnl lock to protect the whole monitor function. Signed-off-by: Ding Tianhong Signed-off-by: David S. Miller --- drivers/net/bonding/bond_main.c | 46 ++++++++++++----------------------------- 1 file changed, 13 insertions(+), 33 deletions(-) diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c index a620dfa..535570e 100644 --- a/drivers/net/bonding/bond_main.c +++ b/drivers/net/bonding/bond_main.c @@ -2726,51 +2726,31 @@ void bond_activebackup_arp_mon(struct work_struct *work) struct bonding *bond = container_of(work, struct bonding, arp_work.work); bool should_notify_peers = false; - int delta_in_ticks; - read_lock(&bond->lock); - - delta_in_ticks = msecs_to_jiffies(bond->params.arp_interval); + if (!rtnl_trylock()) + goto re_arm; - if (!bond_has_slaves(bond)) + if (!bond_has_slaves(bond)) { + rtnl_unlock(); goto re_arm; + } should_notify_peers = bond_should_notify_peers(bond); - if (bond_ab_arp_inspect(bond)) { - read_unlock(&bond->lock); - - /* Race avoidance with bond_close flush of workqueue */ - if (!rtnl_trylock()) { - read_lock(&bond->lock); - delta_in_ticks = 1; - should_notify_peers = false; - goto re_arm; - } - - read_lock(&bond->lock); - + if (bond_ab_arp_inspect(bond)) bond_ab_arp_commit(bond); - read_unlock(&bond->lock); - rtnl_unlock(); - read_lock(&bond->lock); - } - bond_ab_arp_probe(bond); -re_arm: - if (bond->params.arp_interval) - queue_delayed_work(bond->wq, &bond->arp_work, delta_in_ticks); + if (should_notify_peers) + call_netdevice_notifiers(NETDEV_NOTIFY_PEERS, bond->dev); - read_unlock(&bond->lock); + rtnl_unlock(); - if (should_notify_peers) { - if (!rtnl_trylock()) - return; - call_netdevice_notifiers(NETDEV_NOTIFY_PEERS, bond->dev); - rtnl_unlock(); - } +re_arm: + if (bond->params.arp_interval) + queue_delayed_work(bond->wq, &bond->arp_work, + msecs_to_jiffies(bond->params.arp_interval)); } /*-------------------------- netdev event handling --------------------------*/ -- 2.7.4