Commit eb9fa4b0 authored by dingtianhong's avatar dingtianhong Committed by David S. Miller
Browse files

bonding: rebuild the lock use for bond_activebackup_arp_mon() 



The bond_activebackup_arp_mon() use the bond lock for read to
protect the slave list, it is no effect, and the RTNL is only
called for bond_ab_arp_commit() and peer notify, for the performance
better, use RCU to replace with the bond lock, to the bond slave
list need to called in RCU, add a new bond_first_slave_rcu()
to get the first slave in RCU protection.

In bond_ab_arp_probe(), the bond->current_arp_slave may changd
if bond release slave, just like:

        bond_ab_arp_probe()                     bond_release()
        cpu 0                                   cpu 1
        ...
        if (bond->current_arp_slave...)         ...
        ...                             bond->current_arp_slave = NULl
        bond->current_arp_slave->dev->name      ...

So the current_arp_slave need to dereference in the section.

Suggested-by: default avatarNikolay Aleksandrov <nikolay@redhat.com>
Suggested-by: default avatarJay Vosburgh <fubar@us.ibm.com>
Suggested-by: default avatarVeaceslav Falico <vfalico@redhat.com>
Signed-off-by: default avatarDing Tianhong <dingtianhong@huawei.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e001bfad

drivers/net/bonding/bond_main.c

+20 −25
Original line number Diff line number Diff line
@@ -2517,7 +2517,7 @@ re_arm: 
 * place for the slave.  Returns 0 if no changes are found, >0 if changes

 * to link states must be committed.

 *

 * Called with bond->lock held for read.

 * Called with rcu_read_lock hold.

 */

static int bond_ab_arp_inspect(struct bonding *bond)

{
@@ -2526,7 +2526,7 @@ static int bond_ab_arp_inspect(struct bonding *bond) 
	struct slave *slave;

	int commit = 0;



	bond_for_each_slave(bond, slave, iter) {

	bond_for_each_slave_rcu(bond, slave, iter) {

		slave->new_link = BOND_LINK_NOCHANGE;

		last_rx = slave_last_rx(bond, slave);
@@ -2588,7 +2588,7 @@ static int bond_ab_arp_inspect(struct bonding *bond) 
 * Called to commit link state changes noted by inspection step of

 * active-backup mode ARP monitor.

 *

 * Called with RTNL and bond->lock for read.

 * Called with RTNL hold.

 */

static void bond_ab_arp_commit(struct bonding *bond)

{
@@ -2663,19 +2663,20 @@ do_failover: 
/*

 * Send ARP probes for active-backup mode ARP monitor.

 *

 * Called with bond->lock held for read.

 * Called with rcu_read_lock hold.

 */

static void bond_ab_arp_probe(struct bonding *bond)

{

	struct slave *slave, *before = NULL, *new_slave = NULL;

	struct slave *slave, *before = NULL, *new_slave = NULL,

		     *curr_arp_slave = rcu_dereference(bond->current_arp_slave);

	struct list_head *iter;

	bool found = false;



	read_lock(&bond->curr_slave_lock);



	if (bond->current_arp_slave && bond->curr_active_slave)

	if (curr_arp_slave && bond->curr_active_slave)

		pr_info("PROBE: c_arp %s && cas %s BAD\n",

			bond->current_arp_slave->dev->name,

			curr_arp_slave->dev->name,

			bond->curr_active_slave->dev->name);



	if (bond->curr_active_slave) {
@@ -2691,15 +2692,15 @@ static void bond_ab_arp_probe(struct bonding *bond) 
	 * for becoming the curr_active_slave

	 */



	if (!bond->current_arp_slave) {

		bond->current_arp_slave = bond_first_slave(bond);

		if (!bond->current_arp_slave)

	if (!curr_arp_slave) {

		curr_arp_slave = bond_first_slave_rcu(bond);

		if (!curr_arp_slave)

			return;

	}



	bond_set_slave_inactive_flags(bond->current_arp_slave);

	bond_set_slave_inactive_flags(curr_arp_slave);



	bond_for_each_slave(bond, slave, iter) {

	bond_for_each_slave_rcu(bond, slave, iter) {

		if (!found && !before && IS_UP(slave->dev))

			before = slave;
@@ -2722,7 +2723,7 @@ static void bond_ab_arp_probe(struct bonding *bond) 
			pr_info("%s: backup interface %s is now down.\n",

				bond->dev->name, slave->dev->name);

		}

		if (slave == bond->current_arp_slave)

		if (slave == curr_arp_slave)

			found = true;

	}
@@ -2736,8 +2737,7 @@ static void bond_ab_arp_probe(struct bonding *bond) 
	bond_set_slave_active_flags(new_slave);

	bond_arp_send_all(bond, new_slave);

	new_slave->jiffies = jiffies;

	bond->current_arp_slave = new_slave;



	rcu_assign_pointer(bond->current_arp_slave, new_slave);

}



void bond_activebackup_arp_mon(struct work_struct *work)
@@ -2747,43 +2747,38 @@ void bond_activebackup_arp_mon(struct work_struct *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))

		goto re_arm;



	rcu_read_lock();



	should_notify_peers = bond_should_notify_peers(bond);



	if (bond_ab_arp_inspect(bond)) {

		read_unlock(&bond->lock);

		rcu_read_unlock();



		/* 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);



		bond_ab_arp_commit(bond);



		read_unlock(&bond->lock);

		rtnl_unlock();

		read_lock(&bond->lock);

		rcu_read_lock();

	}



	bond_ab_arp_probe(bond);

	rcu_read_unlock();



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;

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