bonding: remove bond read lock for bond_activebackup_arp_mon()
Subsystems (3)
PATCH v2 4/5 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 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 move the rtnl lock to protect the whole monitor function.
Signed-off-by Ding Tianhong <[email protected]>
--- drivers/net/bonding/bond_main.c | 46 ++++++++++++----------------------------- 1 file changed, 13 insertions(+), 33 deletions(-)
drivers/net/bonding/bond_main.c +13 -33
@@ -2763,51 +2763,31 @@ 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 --------------------------*/
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1.8.2.1