bonding: xor/802.3ad improved slave hash

Add support for alternate slave selection algorithms to bonding
balance-xor and 802.3ad modes.  Default mode (what we have now: xor of
MAC addresses) is "layer2", new choice is "layer3+4", using IP and port
information for hashing to select peer.

Originally submitted by Jason Gabler for balance-xor mode;
modified by Jay Vosburgh to additionally support 802.3ad mode.  Jason's
original comment is as follows:

The attached patch to the Linux Etherchannel Bonding driver modifies the
driver's "balance-xor" mode as follows:

      - alternate hashing policy support for mode 2
        * Added kernel parameter "xmit_policy" to allow the specification
          of different hashing policies for mode 2.  The original mode 2
          policy is the default, now found in xmit_hash_policy_layer2().
        * Added xmit_hash_policy_layer34()

This patch was inspired by hashing policies implemented by Cisco,
Foundry and IBM, which are explained in
Foundry documentation found at:
http://www.foundrynet.com/services/documentation/sribcg/Trunking.html#112750

Signed-off-by: Jason Gabler <jygabler@lbl.gov>
Signed-off-by: Jay Vosburgh <fubar@us.ibm.com>

1 files changed, 1 insertions, 2 deletions

diff --git a/drivers/net/bonding/bond_3ad.c b/drivers/net/bonding/bond_3ad.c
index 6233c4ffb805..a2e8dda5afac 100644
--- a/drivers/net/bonding/bond_3ad.c
+++ b/drivers/net/bonding/bond_3ad.c
@@ -2346,7 +2346,6 @@ int bond_3ad_xmit_xor(struct sk_buff *skb, struct net_device *dev)
 {
         struct slave *slave, *start_at;
         struct bonding *bond = dev->priv;
-        struct ethhdr *data = (struct ethhdr *)skb->data;
         int slave_agg_no;
         int slaves_in_agg;
         int agg_id;
@@ -2377,7 +2376,7 @@ int bond_3ad_xmit_xor(struct sk_buff *skb, struct net_device *dev)
                 goto out;
         }
 
-        slave_agg_no = (data->h_dest[5]^bond->dev->dev_addr[5]) % slaves_in_agg;
+        slave_agg_no = bond->xmit_hash_policy(skb, dev, slaves_in_agg);
 
         bond_for_each_slave(bond, slave, i) {
                 struct aggregator *agg = SLAVE_AD_INFO(slave).port.aggregator;