Subject: [PATCH net-next v2 3/10] bonding: rebuild the lock use for bond_alb_monitor()

From: Ding Tianhong <[email-masked]>
Date: Fri, 8 Nov 2013 10:07:52 +0800

The bond_alb_monitor use bond lock to protect the bond slave list,
it is no effect here, we need to use RTNL or RCU to replace bond lock,
the bond_alb_monitor will called 10 times one second, RTNL may loss
performance here, so the bond lock replace with RCU to protect the
bond slave list, also the RTNL is preserved, the logic of the monitor
did not changed.

Suggested-by: Jay Vosburgh <[email-masked]>
Suggested-by: Veaceslav Falico <[email-masked]>
Signed-off-by: Ding Tianhong <[email-masked]>
---
 drivers/net/bonding/bond_alb.c | 21 +++++++++------------
 1 file changed, 9 insertions(+), 12 deletions(-)

diff --git a/drivers/net/bonding/bond_alb.c b/drivers/net/bonding/bond_alb.c
index 1fae915..ffdb91b 100644
--- a/drivers/net/bonding/bond_alb.c
+++ b/drivers/net/bonding/bond_alb.c
@@ -816,7 +816,7 @@ static void rlb_rebalance(struct bonding *bond)
 	for (; hash_index != RLB_NULL_INDEX;
 	     hash_index = client_info->used_next) {
 		client_info = &(bond_info->rx_hashtbl[hash_index]);
-		assigned_slave = rlb_next_rx_slave(bond);
+		assigned_slave = __rlb_next_rx_slave(bond);
 		if (assigned_slave && (client_info->slave != assigned_slave)) {
 			client_info->slave = assigned_slave;
 			client_info->ntt = 1;
@@ -1495,9 +1495,10 @@ void bond_alb_monitor(struct work_struct *work)
 	struct list_head *iter;
 	struct slave *slave;
 
-	read_lock(&bond->lock);
+	rcu_read_lock();
 
-	if (!bond_has_slaves(bond)) {
+	if (!bond_has_slaves_rcu(bond)) {
+		rcu_read_unlock();
 		bond_info->tx_rebalance_counter = 0;
 		bond_info->lp_counter = 0;
 		goto re_arm;
@@ -1528,7 +1529,7 @@ void bond_alb_monitor(struct work_struct *work)
 
 		read_lock(&bond->curr_slave_lock);
 
-		bond_for_each_slave(bond, slave, iter) {
+		bond_for_each_slave_rcu(bond, slave, iter) {
 			tlb_clear_slave(bond, slave, 1);
 			if (slave == bond->curr_active_slave) {
 				SLAVE_TLB_INFO(slave).load =
@@ -1552,11 +1553,9 @@ void bond_alb_monitor(struct work_struct *work)
 			 * dev_set_promiscuity requires rtnl and
 			 * nothing else.  Avoid race with bond_close.
 			 */
-			read_unlock(&bond->lock);
-			if (!rtnl_trylock()) {
-				read_lock(&bond->lock);
+			rcu_read_unlock();
+			if (!rtnl_trylock())
 				goto re_arm;
-			}
 
 			bond_info->rlb_promisc_timeout_counter = 0;
 
@@ -1568,7 +1567,7 @@ void bond_alb_monitor(struct work_struct *work)
 			bond_info->primary_is_promisc = 0;
 
 			rtnl_unlock();
-			read_lock(&bond->lock);
+			rcu_read_lock();
 		}
 
 		if (bond_info->rlb_rebalance) {
@@ -1590,11 +1589,9 @@ void bond_alb_monitor(struct work_struct *work)
 			}
 		}
 	}
-
+	rcu_read_unlock();
 re_arm:
 	queue_delayed_work(bond->wq, &bond->alb_work, alb_delta_in_ticks);
-
-	read_unlock(&bond->lock);
 }
 
 /* assumption: called before the slave is attached to the bond
-- 
1.8.2.1