Commit da210f55 authored by Jiri Bohac's avatar Jiri Bohac Committed by David S. Miller
Browse files

bonding: add some slack to arp monitoring time limits 



Currently, all the time limits in the bonding ARP monitor are in
multiples of arp_interval -- the time interval at which the ARP
monitor is periodically scheduled.

With a fast network round-trip and a little scheduling latency
of the ARP monitor work, a limit of n*delta_in_ticks may
effectively mean (n-1)*delta_in_ticks.

This is fatal in case of n==1  (the link will stay down
forever) and makes the behaviour non-deterministic in all the
other cases.

Add a delta_in_ticks/2 time slack to all the time limits.

Signed-off-by: default avatarJiri Bohac <jbohac@suse.cz>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent eb7e0575

drivers/net/bonding/bond_main.c

+20 −11
Original line number Diff line number Diff line
@@ -2811,12 +2811,13 @@ void bond_loadbalance_arp_mon(struct work_struct *work) 
					    arp_work.work);

	struct slave *slave, *oldcurrent;

	int do_failover = 0;

	int delta_in_ticks;

	int delta_in_ticks, extra_ticks;

	int i;



	read_lock(&bond->lock);



	delta_in_ticks = msecs_to_jiffies(bond->params.arp_interval);

	extra_ticks = delta_in_ticks / 2;



	if (bond->slave_cnt == 0)

		goto re_arm;
@@ -2839,10 +2840,10 @@ void bond_loadbalance_arp_mon(struct work_struct *work) 
		if (slave->link != BOND_LINK_UP) {

			if (time_in_range(jiffies,

				trans_start - delta_in_ticks,

				trans_start + delta_in_ticks) &&

				trans_start + delta_in_ticks + extra_ticks) &&

			    time_in_range(jiffies,

				slave->dev->last_rx - delta_in_ticks,

				slave->dev->last_rx + delta_in_ticks)) {

				slave->dev->last_rx + delta_in_ticks + extra_ticks)) {



				slave->link  = BOND_LINK_UP;

				bond_set_active_slave(slave);
@@ -2872,10 +2873,10 @@ void bond_loadbalance_arp_mon(struct work_struct *work) 
			 */

			if (!time_in_range(jiffies,

				trans_start - delta_in_ticks,

				trans_start + 2 * delta_in_ticks) ||

				trans_start + 2 * delta_in_ticks + extra_ticks) ||

			    !time_in_range(jiffies,

				slave->dev->last_rx - delta_in_ticks,

				slave->dev->last_rx + 2 * delta_in_ticks)) {

				slave->dev->last_rx + 2 * delta_in_ticks + extra_ticks)) {



				slave->link  = BOND_LINK_DOWN;

				bond_set_backup_slave(slave);
@@ -2933,6 +2934,14 @@ static int bond_ab_arp_inspect(struct bonding *bond, int delta_in_ticks) 
	struct slave *slave;

	int i, commit = 0;

	unsigned long trans_start;

	int extra_ticks;



	/* All the time comparisons below need some extra time. Otherwise, on

	 * fast networks the ARP probe/reply may arrive within the same jiffy

	 * as it was sent.  Then, the next time the ARP monitor is run, one

	 * arp_interval will already have passed in the comparisons.

	 */

	extra_ticks = delta_in_ticks / 2;



	bond_for_each_slave(bond, slave, i) {

		slave->new_link = BOND_LINK_NOCHANGE;
@@ -2940,7 +2949,7 @@ static int bond_ab_arp_inspect(struct bonding *bond, int delta_in_ticks) 
		if (slave->link != BOND_LINK_UP) {

			if (time_in_range(jiffies,

				slave_last_rx(bond, slave) - delta_in_ticks,

				slave_last_rx(bond, slave) + delta_in_ticks)) {

				slave_last_rx(bond, slave) + delta_in_ticks + extra_ticks)) {



				slave->new_link = BOND_LINK_UP;

				commit++;
@@ -2956,7 +2965,7 @@ static int bond_ab_arp_inspect(struct bonding *bond, int delta_in_ticks) 
		 */

		if (time_in_range(jiffies,

				  slave->jiffies - delta_in_ticks,

				  slave->jiffies + 2 * delta_in_ticks))

				  slave->jiffies + 2 * delta_in_ticks + extra_ticks))

			continue;



		/*
@@ -2976,7 +2985,7 @@ static int bond_ab_arp_inspect(struct bonding *bond, int delta_in_ticks) 
		    !bond->current_arp_slave &&

		    !time_in_range(jiffies,

			slave_last_rx(bond, slave) - delta_in_ticks,

			slave_last_rx(bond, slave) + 3 * delta_in_ticks)) {

			slave_last_rx(bond, slave) + 3 * delta_in_ticks + extra_ticks)) {



			slave->new_link = BOND_LINK_DOWN;

			commit++;
@@ -2992,10 +3001,10 @@ static int bond_ab_arp_inspect(struct bonding *bond, int delta_in_ticks) 
		if (bond_is_active_slave(slave) &&

		    (!time_in_range(jiffies,

			trans_start - delta_in_ticks,

			trans_start + 2 * delta_in_ticks) ||

			trans_start + 2 * delta_in_ticks + extra_ticks) ||

		     !time_in_range(jiffies,

			slave_last_rx(bond, slave) - delta_in_ticks,

			slave_last_rx(bond, slave) + 2 * delta_in_ticks))) {

			slave_last_rx(bond, slave) + 2 * delta_in_ticks + extra_ticks))) {



			slave->new_link = BOND_LINK_DOWN;

			commit++;
@@ -3027,7 +3036,7 @@ static void bond_ab_arp_commit(struct bonding *bond, int delta_in_ticks) 
			if ((!bond->curr_active_slave &&

			     time_in_range(jiffies,

					   trans_start - delta_in_ticks,

					   trans_start + delta_in_ticks)) ||

					   trans_start + delta_in_ticks + delta_in_ticks / 2)) ||

			    bond->curr_active_slave != slave) {

				slave->link = BOND_LINK_UP;

				if (bond->current_arp_slave) {

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