bonding: fix locking during alb failover and slave removal

	alb_fasten_mac_swap (actually rlb_teach_disabled_mac_on_primary)
requries RTNL and no other locks.  This could cause dev_set_promiscuity
and/or dev_set_mac_address to be called with improper locking.

	Changed callers to hold only RTNL during calls to alb_fasten_mac_swap
or functions calling it.  Updated header comments in affected functions to
reflect proper reality of locking requirements.

Signed-off-by: Jay Vosburgh <fubar@us.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

2 files changed, 20 insertions, 12 deletions

diff --git a/drivers/net/bonding/bond_alb.c b/drivers/net/bonding/bond_alb.c
index 9b55a123c08f..b57bc9467dbe 100644
--- a/drivers/net/bonding/bond_alb.c
+++ b/drivers/net/bonding/bond_alb.c
@@ -979,7 +979,7 @@ static void alb_swap_mac_addr(struct bonding *bond, struct slave *slave1, struct
 /*
  * Send learning packets after MAC address swap.
  *
- * Called with RTNL and bond->lock held for read.
+ * Called with RTNL and no other locks
  */
 static void alb_fasten_mac_swap(struct bonding *bond, struct slave *slave1,
                                 struct slave *slave2)
@@ -987,6 +987,8 @@ static void alb_fasten_mac_swap(struct bonding *bond, struct slave *slave1,
         int slaves_state_differ = (SLAVE_IS_OK(slave1) != SLAVE_IS_OK(slave2));
         struct slave *disabled_slave = NULL;
 
+        ASSERT_RTNL();
+
         /* fasten the change in the switch */
         if (SLAVE_IS_OK(slave1)) {
                 alb_send_learning_packets(slave1, slave1->dev->dev_addr);
@@ -1031,7 +1033,7 @@ static void alb_fasten_mac_swap(struct bonding *bond, struct slave *slave1,
  * a slave that has @slave's permanet address as its current address.
  * We'll make sure that that slave no longer uses @slave's permanent address.
  *
- * Caller must hold bond lock
+ * Caller must hold RTNL and no other locks
  */
 static void alb_change_hw_addr_on_detach(struct bonding *bond, struct slave *slave)
 {
@@ -1542,7 +1544,12 @@ int bond_alb_init_slave(struct bonding *bond, struct slave *slave)
         return 0;
 }
 
-/* Caller must hold bond lock for write */
+/*
+ * Remove slave from tlb and rlb hash tables, and fix up MAC addresses
+ * if necessary.
+ *
+ * Caller must hold RTNL and no other locks
+ */
 void bond_alb_deinit_slave(struct bonding *bond, struct slave *slave)
 {
         if (bond->slave_cnt > 1) {
@@ -1658,12 +1665,11 @@ void bond_alb_handle_active_change(struct bonding *bond, struct slave *new_slave
                                        bond->alb_info.rlb_enabled);
         }
 
-        read_lock(&bond->lock);
-
         if (swap_slave) {
                 alb_fasten_mac_swap(bond, swap_slave, new_slave);
+                read_lock(&bond->lock);
         } else {
-                /* fasten bond mac on new current slave */
+                read_lock(&bond->lock);
                 alb_send_learning_packets(new_slave, bond->dev->dev_addr);
         }
 
diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index b0b26036266b..77d004d3c554 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -1746,7 +1746,9 @@ int bond_release(struct net_device *bond_dev, struct net_device *slave_dev)
                  * has been cleared (if our_slave == old_current),
                  * but before a new active slave is selected.
                  */
+                write_unlock_bh(&bond->lock);
                 bond_alb_deinit_slave(bond, slave);
+                write_lock_bh(&bond->lock);
         }
 
         if (oldcurrent == slave) {
@@ -1905,6 +1907,12 @@ static int bond_release_all(struct net_device *bond_dev)
                 slave_dev = slave->dev;
                 bond_detach_slave(bond, slave);
 
+                /* now that the slave is detached, unlock and perform
+                 * all the undo steps that should not be called from
+                 * within a lock.
+                 */
+                write_unlock_bh(&bond->lock);
+
                 if ((bond->params.mode == BOND_MODE_TLB) ||
                     (bond->params.mode == BOND_MODE_ALB)) {
                         /* must be called only after the slave
@@ -1915,12 +1923,6 @@ static int bond_release_all(struct net_device *bond_dev)
 
                 bond_compute_features(bond);
 
-                /* now that the slave is detached, unlock and perform
-                 * all the undo steps that should not be called from
-                 * within a lock.
-                 */
-                write_unlock_bh(&bond->lock);
-
                 bond_destroy_slave_symlinks(bond_dev, slave_dev);
                 bond_del_vlans_from_slave(bond, slave_dev);