bonding: Convert locks to _bh, rework alb locking for new locking

	Convert locking-related activity to new & improved system.
Convert some lock acquisitions to _bh and rework parts of ALB mode, both
to avoid deadlocks with workqueue activity.

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

1 files changed, 63 insertions, 6 deletions

diff --git a/drivers/net/bonding/bond_alb.c b/drivers/net/bonding/bond_alb.c
index eb320c3cbdde..f2e2872c9b17 100644
--- a/drivers/net/bonding/bond_alb.c
+++ b/drivers/net/bonding/bond_alb.c
@@ -959,19 +959,34 @@ static int alb_set_slave_mac_addr(struct slave *slave, u8 addr[], int hw)
         return 0;
 }
 
-/* Caller must hold bond lock for write or curr_slave_lock for write*/
+/*
+ * Swap MAC addresses between two slaves.
+ *
+ * Called with RTNL held, and no other locks.
+ *
+ */
+
 static void alb_swap_mac_addr(struct bonding *bond, struct slave *slave1, struct slave *slave2)
 {
-        struct slave *disabled_slave = NULL;
         u8 tmp_mac_addr[ETH_ALEN];
-        int slaves_state_differ;
-
-        slaves_state_differ = (SLAVE_IS_OK(slave1) != SLAVE_IS_OK(slave2));
 
         memcpy(tmp_mac_addr, slave1->dev->dev_addr, ETH_ALEN);
         alb_set_slave_mac_addr(slave1, slave2->dev->dev_addr, bond->alb_info.rlb_enabled);
         alb_set_slave_mac_addr(slave2, tmp_mac_addr, bond->alb_info.rlb_enabled);
 
+}
+
+/*
+ * Send learning packets after MAC address swap.
+ *
+ * Called with RTNL and bond->lock held for read.
+ */
+static void alb_fasten_mac_swap(struct bonding *bond, struct slave *slave1,
+                                struct slave *slave2)
+{
+        int slaves_state_differ = (SLAVE_IS_OK(slave1) != SLAVE_IS_OK(slave2));
+        struct slave *disabled_slave = NULL;
+
         /* fasten the change in the switch */
         if (SLAVE_IS_OK(slave1)) {
                 alb_send_learning_packets(slave1, slave1->dev->dev_addr);
@@ -1044,7 +1059,9 @@ static void alb_change_hw_addr_on_detach(struct bonding *bond, struct slave *sla
                 }
 
                 if (found) {
+                        /* locking: needs RTNL and nothing else */
                         alb_swap_mac_addr(bond, slave, tmp_slave);
+                        alb_fasten_mac_swap(bond, slave, tmp_slave);
                 }
         }
 }
@@ -1571,13 +1588,21 @@ void bond_alb_handle_link_change(struct bonding *bond, struct slave *slave, char
  * Set the bond->curr_active_slave to @new_slave and handle
  * mac address swapping and promiscuity changes as needed.
  *
- * Caller must hold bond curr_slave_lock for write (or bond lock for write)
+ * If new_slave is NULL, caller must hold curr_slave_lock or
+ * bond->lock for write.
+ *
+ * If new_slave is not NULL, caller must hold RTNL, bond->lock for
+ * read and curr_slave_lock for write.  Processing here may sleep, so
+ * no other locks may be held.
  */
 void bond_alb_handle_active_change(struct bonding *bond, struct slave *new_slave)
 {
         struct slave *swap_slave;
         int i;
 
+        if (new_slave)
+                ASSERT_RTNL();
+
         if (bond->curr_active_slave == new_slave) {
                 return;
         }
@@ -1610,6 +1635,19 @@ void bond_alb_handle_active_change(struct bonding *bond, struct slave *new_slave
                 }
         }
 
+        /*
+         * Arrange for swap_slave and new_slave to temporarily be
+         * ignored so we can mess with their MAC addresses without
+         * fear of interference from transmit activity.
+         */
+        if (swap_slave) {
+                tlb_clear_slave(bond, swap_slave, 1);
+        }
+        tlb_clear_slave(bond, new_slave, 1);
+
+        write_unlock_bh(&bond->curr_slave_lock);
+        read_unlock(&bond->lock);
+
         /* curr_active_slave must be set before calling alb_swap_mac_addr */
         if (swap_slave) {
                 /* swap mac address */
@@ -1618,11 +1656,23 @@ void bond_alb_handle_active_change(struct bonding *bond, struct slave *new_slave
                 /* set the new_slave to the bond mac address */
                 alb_set_slave_mac_addr(new_slave, bond->dev->dev_addr,
                                        bond->alb_info.rlb_enabled);
+        }
+
+        read_lock(&bond->lock);
+
+        if (swap_slave) {
+                alb_fasten_mac_swap(bond, swap_slave, new_slave);
+        } else {
                 /* fasten bond mac on new current slave */
                 alb_send_learning_packets(new_slave, bond->dev->dev_addr);
         }
+
+        write_lock_bh(&bond->curr_slave_lock);
 }
 
+/*
+ * Called with RTNL
+ */
 int bond_alb_set_mac_address(struct net_device *bond_dev, void *addr)
 {
         struct bonding *bond = bond_dev->priv;
@@ -1659,8 +1709,12 @@ int bond_alb_set_mac_address(struct net_device *bond_dev, void *addr)
                 }
         }
 
+        write_unlock_bh(&bond->curr_slave_lock);
+        read_unlock(&bond->lock);
+
         if (swap_slave) {
                 alb_swap_mac_addr(bond, swap_slave, bond->curr_active_slave);
+                alb_fasten_mac_swap(bond, swap_slave, bond->curr_active_slave);
         } else {
                 alb_set_slave_mac_addr(bond->curr_active_slave, bond_dev->dev_addr,
                                        bond->alb_info.rlb_enabled);
@@ -1672,6 +1726,9 @@ int bond_alb_set_mac_address(struct net_device *bond_dev, void *addr)
                 }
         }
 
+        read_lock(&bond->lock);
+        write_lock_bh(&bond->curr_slave_lock);
+
         return 0;
 }