Commit f2ebd477 authored by Veaceslav Falico's avatar Veaceslav Falico Committed by David S. Miller
Browse files

bonding: restructure locking of bond_ab_arp_probe() 



Currently we're calling it from under RCU context, however we're using some
functions that require rtnl to be held.

Fix this by restructuring the locking - don't call it under any locks,
aquire rcu_read_lock() if we're sending _only_ (i.e. we have the active
slave present), and use rtnl locking otherwise - if we need to modify
(in)active flags of a slave.

CC: Jay Vosburgh <fubar@us.ibm.com>
CC: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: default avatarVeaceslav Falico <vfalico@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 98b90f26

drivers/net/bonding/bond_main.c

+36 −21
Original line number Diff line number Diff line
@@ -2599,17 +2599,18 @@ do_failover: 


/*

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

 *

 * Called with rcu_read_lock hold.

 */

static void bond_ab_arp_probe(struct bonding *bond)

static bool bond_ab_arp_probe(struct bonding *bond)

{

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

		     *curr_arp_slave = rcu_dereference(bond->current_arp_slave),

		     *curr_active_slave = rcu_dereference(bond->curr_active_slave);

		     *curr_arp_slave, *curr_active_slave;

	struct list_head *iter;

	bool found = false;



	rcu_read_lock();

	curr_arp_slave = rcu_dereference(bond->current_arp_slave);

	curr_active_slave = rcu_dereference(bond->curr_active_slave);



	if (curr_arp_slave && curr_active_slave)

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

			curr_arp_slave->dev->name,
@@ -2617,23 +2618,32 @@ static void bond_ab_arp_probe(struct bonding *bond) 


	if (curr_active_slave) {

		bond_arp_send_all(bond, curr_active_slave);

		return;

		rcu_read_unlock();

		return true;

	}

	rcu_read_unlock();



	/* if we don't have a curr_active_slave, search for the next available

	 * backup slave from the current_arp_slave and make it the candidate

	 * for becoming the curr_active_slave

	 */



	if (!rtnl_trylock())

		return false;

	/* curr_arp_slave might have gone away */

	curr_arp_slave = ACCESS_ONCE(bond->current_arp_slave);



	if (!curr_arp_slave) {

		curr_arp_slave = bond_first_slave_rcu(bond);

		if (!curr_arp_slave)

			return;

		curr_arp_slave = bond_first_slave(bond);

		if (!curr_arp_slave) {

			rtnl_unlock();

			return true;

		}

	}



	bond_set_slave_inactive_flags(curr_arp_slave);



	bond_for_each_slave_rcu(bond, slave, iter) {

	bond_for_each_slave(bond, slave, iter) {

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

			before = slave;
@@ -2663,21 +2673,26 @@ static void bond_ab_arp_probe(struct bonding *bond) 
	if (!new_slave && before)

		new_slave = before;



	if (!new_slave)

		return;

	if (!new_slave) {

		rtnl_unlock();

		return true;

	}



	new_slave->link = BOND_LINK_BACK;

	bond_set_slave_active_flags(new_slave);

	bond_arp_send_all(bond, new_slave);

	new_slave->jiffies = jiffies;

	rcu_assign_pointer(bond->current_arp_slave, new_slave);

	rtnl_unlock();



	return true;

}



static 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;

	bool should_notify_peers = false, should_commit = false;

	int delta_in_ticks;



	delta_in_ticks = msecs_to_jiffies(bond->params.arp_interval);
@@ -2686,12 +2701,11 @@ static void bond_activebackup_arp_mon(struct work_struct *work) 
		goto re_arm;



	rcu_read_lock();



	should_notify_peers = bond_should_notify_peers(bond);



	if (bond_ab_arp_inspect(bond)) {

	should_commit = bond_ab_arp_inspect(bond);

	rcu_read_unlock();



	if (should_commit) {

		/* Race avoidance with bond_close flush of workqueue */

		if (!rtnl_trylock()) {

			delta_in_ticks = 1;
@@ -2700,13 +2714,14 @@ static void bond_activebackup_arp_mon(struct work_struct *work) 
		}



		bond_ab_arp_commit(bond);



		rtnl_unlock();

		rcu_read_lock();

	}



	bond_ab_arp_probe(bond);

	rcu_read_unlock();

	if (!bond_ab_arp_probe(bond)) {

		/* rtnl locking failed, re-arm */

		delta_in_ticks = 1;

		should_notify_peers = false;

	}



re_arm:

	if (bond->params.arp_interval)

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