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Commit 80b9d236 authored by dingtianhong's avatar dingtianhong Committed by David S. Miller
Browse files

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: default avatarDing Tianhong <dingtianhong@huawei.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 7f1bb571

drivers/net/bonding/bond_main.c

+13 −33
Original line number Diff line number Diff line
@@ -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 (!bond_has_slaves(bond))

	if (!rtnl_trylock())

		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;

	if (!bond_has_slaves(bond)) {

		rtnl_unlock();

		goto re_arm;

	}



		read_lock(&bond->lock);

	should_notify_peers = bond_should_notify_peers(bond);



	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);



	read_unlock(&bond->lock);



	if (should_notify_peers) {

		if (!rtnl_trylock())

			return;

	if (should_notify_peers)

		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 --------------------------*/