bonding: Simplify the xmit function for modes that use xmit_hash

Earlier change to use usable slave array for TLB mode had an additional
performance advantage. So extending the same logic to all other modes
that use xmit-hash for slave selection (viz 802.3AD, and XOR modes).
Also consolidating this with the earlier TLB change.

The main idea is to build the usable slaves array in the control path
and use that array for slave selection during xmit operation.

Measured performance in a setup with a bond of 4x1G NICs with 200
instances of netperf for the modes involved (3ad, xor, tlb)
cmd: netperf -t TCP_RR -H <TargetHost> -l 60 -s 5

Mode        TPS-Before   TPS-After

802.3ad   : 468,694      493,101
TLB (lb=0): 392,583      392,965
XOR       : 475,696      484,517

Signed-off-by: Mahesh Bandewar <maheshb@google.com>
Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 44 deletions

diff --git a/drivers/net/bonding/bond_alb.c b/drivers/net/bonding/bond_alb.c
index 615f3bebd019..d2eadab787c5 100644
--- a/drivers/net/bonding/bond_alb.c
+++ b/drivers/net/bonding/bond_alb.c
@@ -177,7 +177,6 @@ static int tlb_initialize(struct bonding *bond)
 static void tlb_deinitialize(struct bonding *bond)
 {
 	struct alb_bond_info *bond_info = &(BOND_ALB_INFO(bond));
-	struct tlb_up_slave *arr;
 
 	spin_lock_bh(&bond->mode_lock);
 
@@ -185,10 +184,6 @@ static void tlb_deinitialize(struct bonding *bond)
 	bond_info->tx_hashtbl = NULL;
 
 	spin_unlock_bh(&bond->mode_lock);
-
-	arr = rtnl_dereference(bond_info->slave_arr);
-	if (arr)
-		kfree_rcu(arr, rcu);
 }
 
 static long long compute_gap(struct slave *slave)
@@ -1336,39 +1331,9 @@ out:
 	return NETDEV_TX_OK;
 }
 
-static int bond_tlb_update_slave_arr(struct bonding *bond,
-				     struct slave *skipslave)
-{
-	struct alb_bond_info *bond_info = &(BOND_ALB_INFO(bond));
-	struct slave *tx_slave;
-	struct list_head *iter;
-	struct tlb_up_slave *new_arr, *old_arr;
-
-	new_arr = kzalloc(offsetof(struct tlb_up_slave, arr[bond->slave_cnt]),
-			  GFP_ATOMIC);
-	if (!new_arr)
-		return -ENOMEM;
-
-	bond_for_each_slave(bond, tx_slave, iter) {
-		if (!bond_slave_can_tx(tx_slave))
-			continue;
-		if (skipslave == tx_slave)
-			continue;
-		new_arr->arr[new_arr->count++] = tx_slave;
-	}
-
-	old_arr = rtnl_dereference(bond_info->slave_arr);
-	rcu_assign_pointer(bond_info->slave_arr, new_arr);
-	if (old_arr)
-		kfree_rcu(old_arr, rcu);
-
-	return 0;
-}
-
 int bond_tlb_xmit(struct sk_buff *skb, struct net_device *bond_dev)
 {
 	struct bonding *bond = netdev_priv(bond_dev);
-	struct alb_bond_info *bond_info = &(BOND_ALB_INFO(bond));
 	struct ethhdr *eth_data;
 	struct slave *tx_slave = NULL;
 	u32 hash_index;
@@ -1389,12 +1354,14 @@ int bond_tlb_xmit(struct sk_buff *skb, struct net_device *bond_dev)
 							      hash_index & 0xFF,
 							      skb->len);
 			} else {
-				struct tlb_up_slave *slaves;
+				struct bond_up_slave *slaves;
+				unsigned int count;
 
-				slaves = rcu_dereference(bond_info->slave_arr);
-				if (slaves && slaves->count)
+				slaves = rcu_dereference(bond->slave_arr);
+				count = slaves ? ACCESS_ONCE(slaves->count) : 0;
+				if (likely(count))
 					tx_slave = slaves->arr[hash_index %
-							       slaves->count];
+							       count];
 			}
 			break;
 		}
@@ -1641,10 +1608,6 @@ void bond_alb_deinit_slave(struct bonding *bond, struct slave *slave)
 		rlb_clear_slave(bond, slave);
 	}
 
-	if (bond_is_nondyn_tlb(bond))
-		if (bond_tlb_update_slave_arr(bond, slave))
-			pr_err("Failed to build slave-array for TLB mode.\n");
-
 }
 
 void bond_alb_handle_link_change(struct bonding *bond, struct slave *slave, char link)
@@ -1669,7 +1632,7 @@ void bond_alb_handle_link_change(struct bonding *bond, struct slave *slave, char
 	}
 
 	if (bond_is_nondyn_tlb(bond)) {
-		if (bond_tlb_update_slave_arr(bond, NULL))
+		if (bond_update_slave_arr(bond, NULL))
 			pr_err("Failed to build slave-array for TLB mode.\n");
 	}
 }