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 <[e-mail]>
Signed-off-by: Jay Vosburgh <[e-mail]>
Signed-off-by: Jeff Garzik <[e-mail]>

drivers/net/bonding/bond_alb.c

···
 	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)) {
···
 		}
 
 		if (found) {
+			/* locking: needs RTNL and nothing else */
 			alb_swap_mac_addr(bond, slave, tmp_slave);
+			alb_fasten_mac_swap(bond, slave, tmp_slave);
 		}
 	}
 }
···
  * 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;
···
 		}
 	}
 
+	/*
+	 * 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 */
···
 		/* 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;
···
 		}
 	}
 
+	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);
···
 			rlb_req_update_slave_clients(bond, bond->curr_active_slave);
 		}
 	}
+
+	read_lock(&bond->lock);
+	write_lock_bh(&bond->curr_slave_lock);
 
 	return 0;
 }

drivers/net/bonding/bond_main.c

···
 	case BOND_MODE_TLB:
 	case BOND_MODE_ALB:
 		new_slave->state = BOND_STATE_ACTIVE;
-		if ((!bond->curr_active_slave) &&
-		    (new_slave->link != BOND_LINK_DOWN)) {
-			/* first slave or no active slave yet, and this link
-			 * is OK, so make this interface the active one
-			 */
-			bond_change_active_slave(bond, new_slave);
-		} else {
-			bond_set_slave_inactive_flags(new_slave);
-		}
+		bond_set_slave_inactive_flags(new_slave);
 		break;
 	default:
 		dprintk("This slave is always active in trunk mode\n");
···
 		bond_alb_deinit_slave(bond, slave);
 	}
 
-	if (oldcurrent == slave)
+	if (oldcurrent == slave) {
+		/*
+		 * Note that we hold RTNL over this sequence, so there
+		 * is no concern that another slave add/remove event
+		 * will interfere.
+		 */
+		write_unlock_bh(&bond->lock);
+		read_lock(&bond->lock);
+		write_lock_bh(&bond->curr_slave_lock);
+
 		bond_select_active_slave(bond);
+
+		write_unlock_bh(&bond->curr_slave_lock);
+		read_unlock(&bond->lock);
+		write_lock_bh(&bond->lock);
+	}
 
 	if (bond->slave_cnt == 0) {
 		bond_set_carrier(bond);
···
 		return -EINVAL;
 	}
 
-	write_lock_bh(&bond->lock);
+	read_lock(&bond->lock);
 
+	read_lock(&bond->curr_slave_lock);
 	old_active = bond->curr_active_slave;
+	read_unlock(&bond->curr_slave_lock);
+
 	new_active = bond_get_slave_by_dev(bond, slave_dev);
 
 	/*
 	 * Changing to the current active: do nothing; return success.
 	 */
 	if (new_active && (new_active == old_active)) {
-		write_unlock_bh(&bond->lock);
+		read_unlock(&bond->lock);
 		return 0;
 	}
 
···
 	    (old_active) &&
 	    (new_active->link == BOND_LINK_UP) &&
 	    IS_UP(new_active->dev)) {
+		write_lock_bh(&bond->curr_slave_lock);
 		bond_change_active_slave(bond, new_active);
+		write_unlock_bh(&bond->curr_slave_lock);
 	} else {
 		res = -EINVAL;
 	}
 
-	write_unlock_bh(&bond->lock);
+	read_unlock(&bond->lock);
 
 	return res;
 }
···
 		switch (slave->link) {
 		case BOND_LINK_UP:	/* the link was up */
 			if (link_state == BMSR_LSTATUS) {
-				/* link stays up, nothing more to do */
+				if (!oldcurrent) {
+					if (!have_locks)
+						return 1;
+					do_failover = 1;
+				}
 				break;
 			} else { /* link going down */
 				slave->link  = BOND_LINK_FAIL;
···
 	} /* end of for */
 
 	if (do_failover) {
-		write_lock(&bond->curr_slave_lock);
+		ASSERT_RTNL();
+
+		write_lock_bh(&bond->curr_slave_lock);
 
 		bond_select_active_slave(bond);
 
-		write_unlock(&bond->curr_slave_lock);
+		write_unlock_bh(&bond->curr_slave_lock);
+
 	} else
 		bond_set_carrier(bond);
 
···
 	}
 
 	if (do_failover) {
-		write_lock(&bond->curr_slave_lock);
+		rtnl_lock();
+		write_lock_bh(&bond->curr_slave_lock);
 
 		bond_select_active_slave(bond);
 
-		write_unlock(&bond->curr_slave_lock);
+		write_unlock_bh(&bond->curr_slave_lock);
+		rtnl_unlock();
+
 	}
 
 re_arm:
···
 
 				slave->link = BOND_LINK_UP;
 
-				write_lock(&bond->curr_slave_lock);
+				rtnl_lock();
+
+				write_lock_bh(&bond->curr_slave_lock);
 
 				if ((!bond->curr_active_slave) &&
 				    ((jiffies - slave->dev->trans_start) <= delta_in_ticks)) {
···
 					       slave->dev->name);
 				}
 
-				write_unlock(&bond->curr_slave_lock);
+				write_unlock_bh(&bond->curr_slave_lock);
+				rtnl_unlock();
 			}
 		} else {
 			read_lock(&bond->curr_slave_lock);
···
 			       bond->dev->name,
 			       slave->dev->name);
 
-			write_lock(&bond->curr_slave_lock);
+			rtnl_lock();
+			write_lock_bh(&bond->curr_slave_lock);
 
 			bond_select_active_slave(bond);
 			slave = bond->curr_active_slave;
 
-			write_unlock(&bond->curr_slave_lock);
+			write_unlock_bh(&bond->curr_slave_lock);
+
+			rtnl_unlock();
 
 			bond->current_arp_slave = slave;
 
···
 			       bond->primary_slave->dev->name);
 
 			/* primary is up so switch to it */
-			write_lock(&bond->curr_slave_lock);
+			rtnl_lock();
+			write_lock_bh(&bond->curr_slave_lock);
 			bond_change_active_slave(bond, bond->primary_slave);
-			write_unlock(&bond->curr_slave_lock);
+			write_unlock_bh(&bond->curr_slave_lock);
+
+			rtnl_unlock();
 
 			slave = bond->primary_slave;
 			slave->jiffies = jiffies;