From: Maor Gottlieb <maorg@mellanox.com>
Date: Thu, 30 Apr 2020 22:21:35 +0300
Subject: bonding: Add helper function to get the xmit slave based on hash
Patch-mainline: v5.8-rc1
Git-commit: c071d91d2a89b0dac1354673810b36453aed62c4
References: bsc#1176447

Both xor and 802.3ad modes use bond_xmit_hash to get the xmit slave.
Export the logic to helper function so it could be used in the
following patches by the .ndo to get the xmit slave.

Signed-off-by: Maor Gottlieb <maorg@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Reviewed-by: Jay Vosburgh <jay.vosburgh@canonical.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/bonding/bond_main.c |   29 ++++++++++++++++++++++-------
 1 file changed, 22 insertions(+), 7 deletions(-)

--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -4175,6 +4175,23 @@ out:
 	return ret;
 }
 
+static struct slave *bond_xmit_3ad_xor_slave_get(struct bonding *bond,
+						 struct sk_buff *skb,
+						 struct bond_up_slave *slaves)
+{
+	struct slave *slave;
+	unsigned int count;
+	u32 hash;
+
+	hash = bond_xmit_hash(bond, skb);
+	count = slaves ? READ_ONCE(slaves->count) : 0;
+	if (unlikely(!count))
+		return NULL;
+
+	slave = slaves->arr[hash % count];
+	return slave;
+}
+
 /* Use this Xmit function for 3AD as well as XOR modes. The current
  * usable slave array is formed in the control path. The xmit function
  * just calculates hash and sends the packet out.
@@ -4183,16 +4200,14 @@ static netdev_tx_t bond_3ad_xor_xmit(str
 				     struct net_device *dev)
 {
 	struct bonding *bond = netdev_priv(dev);
-	struct slave *slave;
 	struct bond_up_slave *slaves;
-	unsigned int count;
+	struct slave *slave;
 
 	slaves = rcu_dereference(bond->usable_slaves);
-	count = slaves ? READ_ONCE(slaves->count) : 0;
-	if (likely(count)) {
-		slave = slaves->arr[bond_xmit_hash(bond, skb) % count];
-		return bond_dev_queue_xmit(bond, skb, slave->dev);
-	}
+	slave = bond_xmit_3ad_xor_slave_get(bond, skb, slaves);
+	if (likely(slave))
+		bond_dev_queue_xmit(bond, skb, slave->dev);
+
 	return bond_tx_drop(dev, skb);
 }