Subject: [PATCH net-next v5 7/11] bonding: rebuild the lock use for bond_3ad_state_machine_handler()

From: Ding Tianhong <[email-masked]>
Date: Wed, 11 Dec 2013 13:00:58 +0800

The bond_3ad_state_machine_handler() use the bond lock to protect
the bond slave list and slave port, so as the before patch said,
I remove bond lock and replace with RCU.

There was a lot of function need RCU protect, I have two choice
to make the function in RCU-safe, (1) create new similar functions
and make the bond slave list in RCU. (2) modify the existed functions
and make them in read-side critical section, because the RCU
read-side critical sections may be nested.

I choose (2) because it is no need to create more similar functions.

The nots in the function is still too old, clean up the nots.

Suggested-by: Nikolay Aleksandrov <[email-masked]>
Suggested-by: Jay Vosburgh <[email-masked]>
Suggested-by: Veaceslav Falico <[email-masked]>
Signed-off-by: Ding Tianhong <[email-masked]>
---
 drivers/net/bonding/bond_3ad.c | 53 ++++++++++++++++++++++++------------------
 1 file changed, 31 insertions(+), 22 deletions(-)

diff --git a/drivers/net/bonding/bond_3ad.c b/drivers/net/bonding/bond_3ad.c
index 187b1b7..d935da5 100644
--- a/drivers/net/bonding/bond_3ad.c
+++ b/drivers/net/bonding/bond_3ad.c
@@ -147,11 +147,12 @@ static inline struct aggregator *__get_first_agg(struct port *port)
 	struct bonding *bond = __get_bond_by_port(port);
 	struct slave *first_slave;
 
-	// If there's no bond for this port, or bond has no slaves
+	/* If there's no bond for this port, or bond has no slaves */
 	if (bond == NULL)
 		return NULL;
-	first_slave = bond_first_slave(bond);
-
+	rcu_read_lock();
+	first_slave = bond_first_slave_rcu(bond);
+	rcu_read_unlock();
 	return first_slave ? &(SLAVE_AD_INFO(first_slave).aggregator) : NULL;
 }
 
@@ -702,9 +703,13 @@ static struct aggregator *__get_active_agg(struct aggregator *aggregator)
 	struct list_head *iter;
 	struct slave *slave;
 
-	bond_for_each_slave(bond, slave, iter)
-		if (SLAVE_AD_INFO(slave).aggregator.is_active)
+	rcu_read_lock();
+	bond_for_each_slave_rcu(bond, slave, iter)
+		if (SLAVE_AD_INFO(slave).aggregator.is_active) {
+			rcu_read_unlock();
 			return &(SLAVE_AD_INFO(slave).aggregator);
+		}
+	rcu_read_unlock();
 
 	return NULL;
 }
@@ -1471,7 +1476,8 @@ static void ad_agg_selection_logic(struct aggregator *agg)
 	active = __get_active_agg(agg);
 	best = (active && agg_device_up(active)) ? active : NULL;
 
-	bond_for_each_slave(bond, slave, iter) {
+	rcu_read_lock();
+	bond_for_each_slave_rcu(bond, slave, iter) {
 		agg = &(SLAVE_AD_INFO(slave).aggregator);
 
 		agg->is_active = 0;
@@ -1505,7 +1511,7 @@ static void ad_agg_selection_logic(struct aggregator *agg)
 		active->is_active = 1;
 	}
 
-	// if there is new best aggregator, activate it
+	/* if there is new best aggregator, activate it */
 	if (best) {
 		pr_debug("best Agg=%d; P=%d; a k=%d; p k=%d; Ind=%d; Act=%d\n",
 			 best->aggregator_identifier, best->num_of_ports,
@@ -1516,7 +1522,7 @@ static void ad_agg_selection_logic(struct aggregator *agg)
 			 best->lag_ports, best->slave,
 			 best->slave ? best->slave->dev->name : "NULL");
 
-		bond_for_each_slave(bond, slave, iter) {
+		bond_for_each_slave_rcu(bond, slave, iter) {
 			agg = &(SLAVE_AD_INFO(slave).aggregator);
 
 			pr_debug("Agg=%d; P=%d; a k=%d; p k=%d; Ind=%d; Act=%d\n",
@@ -1526,10 +1532,10 @@ static void ad_agg_selection_logic(struct aggregator *agg)
 				 agg->is_individual, agg->is_active);
 		}
 
-		// check if any partner replys
+		/* check if any partner replys */
 		if (best->is_individual) {
 			pr_warning("%s: Warning: No 802.3ad response from the link partner for any adapters in the bond\n",
-				   best->slave ? best->slave->bond->dev->name : "NULL");
+			best->slave ? best->slave->bond->dev->name : "NULL");
 		}
 
 		best->is_active = 1;
@@ -1541,7 +1547,7 @@ static void ad_agg_selection_logic(struct aggregator *agg)
 			 best->partner_oper_aggregator_key,
 			 best->is_individual, best->is_active);
 
-		// disable the ports that were related to the former active_aggregator
+		/* disable the ports that were related to the former active_aggregator */
 		if (active) {
 			for (port = active->lag_ports; port;
 			     port = port->next_port_in_aggregator) {
@@ -1565,6 +1571,8 @@ static void ad_agg_selection_logic(struct aggregator *agg)
 		}
 	}
 
+	rcu_read_unlock();
+
 	bond_3ad_set_carrier(bond);
 }
 
@@ -2068,18 +2076,18 @@ void bond_3ad_state_machine_handler(struct work_struct *work)
 	struct slave *slave;
 	struct port *port;
 
-	read_lock(&bond->lock);
+	rcu_read_lock();
 
-	//check if there are any slaves
+	/* check if there are any slaves */
 	if (!bond_has_slaves(bond))
 		goto re_arm;
 
-	// check if agg_select_timer timer after initialize is timed out
+	/* check if agg_select_timer timer after initialize is timed out */
 	if (BOND_AD_INFO(bond).agg_select_timer && !(--BOND_AD_INFO(bond).agg_select_timer)) {
-		slave = bond_first_slave(bond);
+		slave = bond_first_slave_rcu(bond);
 		port = slave ? &(SLAVE_AD_INFO(slave).port) : NULL;
 
-		// select the active aggregator for the bond
+		/* select the active aggregator for the bond */
 		if (port) {
 			if (!port->slave) {
 				pr_warning("%s: Warning: bond's first port is uninitialized\n",
@@ -2093,8 +2101,8 @@ void bond_3ad_state_machine_handler(struct work_struct *work)
 		bond_3ad_set_carrier(bond);
 	}
 
-	// for each port run the state machines
-	bond_for_each_slave(bond, slave, iter) {
+	/* for each port run the state machines */
+	bond_for_each_slave_rcu(bond, slave, iter) {
 		port = &(SLAVE_AD_INFO(slave).port);
 		if (!port->slave) {
 			pr_warning("%s: Warning: Found an uninitialized port\n",
@@ -2114,7 +2122,7 @@ void bond_3ad_state_machine_handler(struct work_struct *work)
 		ad_mux_machine(port);
 		ad_tx_machine(port);
 
-		// turn off the BEGIN bit, since we already handled it
+		/* turn off the BEGIN bit, since we already handled it */
 		if (port->sm_vars & AD_PORT_BEGIN)
 			port->sm_vars &= ~AD_PORT_BEGIN;
 
@@ -2122,9 +2130,8 @@ void bond_3ad_state_machine_handler(struct work_struct *work)
 	}
 
 re_arm:
+	rcu_read_unlock();
 	queue_delayed_work(bond->wq, &bond->ad_work, ad_delta_in_ticks);
-
-	read_unlock(&bond->lock);
 }
 
 /**
@@ -2303,7 +2310,9 @@ int bond_3ad_set_carrier(struct bonding *bond)
 	struct aggregator *active;
 	struct slave *first_slave;
 
-	first_slave = bond_first_slave(bond);
+	rcu_read_lock();
+	first_slave = bond_first_slave_rcu(bond);
+	rcu_read_unlock();
 	if (!first_slave)
 		return 0;
 	active = __get_active_agg(&(SLAVE_AD_INFO(first_slave).aggregator));
-- 
1.8.2.1