bonding: Add new layer2+3 hash for xor/802.3ad modes

Add new hash for balance-xor and 802.3ad modes. Originally
submitted by "Glenn Griffin" <[e-mail]>; modified by
Jay Vosburgh to move setting of hash policy out of line, tweak the
documentation update and add version update to 3.2.2.

Glenn's original comment follows:

Included is a patch for a new xmit_hash_policy for the bonding driver
that selects slaves based on MAC and IP information. This is a middle
ground between what currently exists in the layer2 only policy and the
layer3+4 policy. This policy strives to be fully 802.3ad compliant by
transmitting every packet of any particular flow over the same link.
As documented the layer3+4 policy is not fully compliant for extreme
cases such as ip fragmentation, so this policy is a nice compromise
for environments that require full compliance but desire more than the
layer2 only policy.

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

Documentation/networking/bonding.txt

···
 
 		This algorithm is 802.3ad compliant.
 
+	layer2+3
+
+		This policy uses a combination of layer2 and layer3
+		protocol information to generate the hash.
+
+		Uses XOR of hardware MAC addresses and IP addresses to
+		generate the hash.  The formula is
+
+		(((source IP XOR dest IP) AND 0xffff) XOR
+			( source MAC XOR destination MAC ))
+				modulo slave count
+
+		This algorithm will place all traffic to a particular
+		network peer on the same slave.  For non-IP traffic,
+		the formula is the same as for the layer2 transmit
+		hash policy.
+
+		This policy is intended to provide a more balanced
+		distribution of traffic than layer2 alone, especially
+		in environments where a layer3 gateway device is
+		required to reach most destinations.
+
+		This algorithm is 802.3ad complient.
+
 	layer3+4
 
 		This policy uses upper layer protocol information,
···
 		or may not tolerate this noncompliance.
 
 	The default value is layer2.  This option was added in bonding
-version 2.6.3.  In earlier versions of bonding, this parameter does
-not exist, and the layer2 policy is the only policy.
+	version 2.6.3.  In earlier versions of bonding, this parameter
+	does not exist, and the layer2 policy is the only policy.  The
+	layer2+3 value was added for bonding version 3.2.2.
 
 
 3. Configuring Bonding Devices

drivers/net/bonding/bond_main.c

···
 struct bond_parm_tbl xmit_hashtype_tbl[] = {
 {	"layer2",		BOND_XMIT_POLICY_LAYER2},
 {	"layer3+4",		BOND_XMIT_POLICY_LAYER34},
+{	"layer2+3",		BOND_XMIT_POLICY_LAYER23},
 {	NULL,			-1},
 };
 
···
 /*---------------------------- Hashing Policies -----------------------------*/
 
 /*
+ * Hash for the output device based upon layer 2 and layer 3 data. If
+ * the packet is not IP mimic bond_xmit_hash_policy_l2()
+ */
+static int bond_xmit_hash_policy_l23(struct sk_buff *skb,
+				     struct net_device *bond_dev, int count)
+{
+	struct ethhdr *data = (struct ethhdr *)skb->data;
+	struct iphdr *iph = ip_hdr(skb);
+
+	if (skb->protocol == __constant_htons(ETH_P_IP)) {
+		return ((ntohl(iph->saddr ^ iph->daddr) & 0xffff) ^
+			(data->h_dest[5] ^ bond_dev->dev_addr[5])) % count;
+	}
+
+	return (data->h_dest[5] ^ bond_dev->dev_addr[5]) % count;
+}
+
+/*
  * Hash for the output device based upon layer 3 and layer 4 data. If
  * the packet is a frag or not TCP or UDP, just use layer 3 data.  If it is
  * altogether not IP, mimic bond_xmit_hash_policy_l2()
···
 
 /*------------------------- Device initialization ---------------------------*/
 
+static void bond_set_xmit_hash_policy(struct bonding *bond)
+{
+	switch (bond->params.xmit_policy) {
+	case BOND_XMIT_POLICY_LAYER23:
+		bond->xmit_hash_policy = bond_xmit_hash_policy_l23;
+		break;
+	case BOND_XMIT_POLICY_LAYER34:
+		bond->xmit_hash_policy = bond_xmit_hash_policy_l34;
+		break;
+	case BOND_XMIT_POLICY_LAYER2:
+	default:
+		bond->xmit_hash_policy = bond_xmit_hash_policy_l2;
+		break;
+	}
+}
+
 /*
  * set bond mode specific net device operations
  */
···
 		break;
 	case BOND_MODE_XOR:
 		bond_dev->hard_start_xmit = bond_xmit_xor;
-		if (bond->params.xmit_policy == BOND_XMIT_POLICY_LAYER34)
-			bond->xmit_hash_policy = bond_xmit_hash_policy_l34;
-		else
-			bond->xmit_hash_policy = bond_xmit_hash_policy_l2;
+		bond_set_xmit_hash_policy(bond);
 		break;
 	case BOND_MODE_BROADCAST:
 		bond_dev->hard_start_xmit = bond_xmit_broadcast;
···
 	case BOND_MODE_8023AD:
 		bond_set_master_3ad_flags(bond);
 		bond_dev->hard_start_xmit = bond_3ad_xmit_xor;
-		if (bond->params.xmit_policy == BOND_XMIT_POLICY_LAYER34)
-			bond->xmit_hash_policy = bond_xmit_hash_policy_l34;
-		else
-			bond->xmit_hash_policy = bond_xmit_hash_policy_l2;
+		bond_set_xmit_hash_policy(bond);
 		break;
 	case BOND_MODE_ALB:
 		bond_set_master_alb_flags(bond);
···
 	for (i = 0; tbl[i].modename; i++) {
 		if ((isdigit(*mode_arg) &&
 		     tbl[i].mode == simple_strtol(mode_arg, NULL, 0)) ||
-		    (strncmp(mode_arg, tbl[i].modename,
-			     strlen(tbl[i].modename)) == 0)) {
+		    (strcmp(mode_arg, tbl[i].modename) == 0)) {
 			return tbl[i].mode;
 		}
 	}

drivers/net/bonding/bonding.h

···
 #include "bond_3ad.h"
 #include "bond_alb.h"
 
-#define DRV_VERSION	"3.2.1"
-#define DRV_RELDATE	"October 15, 2007"
+#define DRV_VERSION	"3.2.2"
+#define DRV_RELDATE	"December 6, 2007"
 #define DRV_NAME	"bonding"
 #define DRV_DESCRIPTION	"Ethernet Channel Bonding Driver"
 

include/linux/if_bonding.h

···
 
 /* hashing types */
 #define BOND_XMIT_POLICY_LAYER2		0 /* layer 2 (MAC only), default */
-#define BOND_XMIT_POLICY_LAYER34	1 /* layer 3+4 (IP ^ MAC) */
+#define BOND_XMIT_POLICY_LAYER34	1 /* layer 3+4 (IP ^ (TCP || UDP)) */
+#define BOND_XMIT_POLICY_LAYER23	2 /* layer 2+3 (IP ^ MAC) */
 
 typedef struct ifbond {
 	__s32 bond_mode;