[PATCH net-next v3 2/3] bonding: modify the old and add new xmit hash policies

Nikolay Aleksandrov
2013-09-26T14:13:23Z

This patch adds two new hash policy modes which use skb_flow_dissect:
3 - Encapsulated layer 2+3
4 - Encapsulated layer 3+4
There should be a good improvement for tunnel users in those modes.
It also changes the old hash functions to:
hash ^= (__force u32)flow.dst ^ (__force u32)flow.src;
hash ^= (hash >> 16);
hash ^= (hash >> 8);

Where hash will be initialized either to L2 hash, that is
SRCMAC[5] XOR DSTMAC[5], or to flow->ports which should be extracted
from the upper layer. Flow's dst and src are also extracted based on the
xmit policy either directly from the buffer or by using skb_flow_dissect,
but in both cases if the protocol is IPv6 then dst and src are obtained by
ipv6_addr_hash() on the real addresses. In case of a non-dissectable
packet, the algorithms fall back to L2 hashing.
The bond_set_mode_ops() function is now obsolete and thus deleted
because it was used only to set the proper hash policy. Also we trim a
pointer from struct bonding because we no longer need to keep the hash
function, now there's only a single hash function - bond_xmit_hash that
works based on bond->params.xmit_policy.

The hash function and skb_flow_dissect were suggested by Eric Dumazet.
The layer names were suggested by Andy Gospodarek, because I suck at
semantics.

Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
---
v2: fix a bug in bond_flow_dissect which might've caused the use of
uninitalized flow_keys and make use of skb_flow_get_ports
v3: no change
One line is intentionally left at 82 chars since it's the whole function
and IMO looks better that way.

drivers/net/bonding/bond_3ad.c | 2 +-
drivers/net/bonding/bond_main.c | 197 ++++++++++++++-------------------------
drivers/net/bonding/bond_sysfs.c | 2 -
drivers/net/bonding/bonding.h | 3 +-
include/uapi/linux/if_bonding.h | 2 +
5 files changed, 72 insertions(+), 134 deletions(-)

diff --git a/drivers/net/bonding/bond_3ad.c b/drivers/net/bonding/bond_3ad.c
index 0d8f427..b3ab703 100644
--- a/drivers/net/bonding/bond_3ad.c
+++ b/drivers/net/bonding/bond_3ad.c
@@ -2442,7 +2442,7 @@ int bond_3ad_xmit_xor(struct sk_buff *skb, struct net_device *dev)
goto out;
}

- slave_agg_no = bond->xmit_hash_policy(skb, slaves_in_agg);
+ slave_agg_no = bond_xmit_hash(bond, skb, slaves_in_agg);

bond_for_each_slave(bond, slave) {
struct aggregator *agg = SLAVE_AD_INFO(slave).port.aggregator;
diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 55bbb8b..498e9e1 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -78,6 +78,7 @@
#include <net/netns/generic.h>
#include <net/pkt_sched.h>
#include <linux/rculist.h>
+#include <net/flow_keys.h>
#include "bonding.h"
#include "bond_3ad.h"
#include "bond_alb.h"
@@ -159,7 +160,8 @@ MODULE_PARM_DESC(min_links, "Minimum number of available links before turning on
module_param(xmit_hash_policy, charp, 0);
MODULE_PARM_DESC(xmit_hash_policy, "balance-xor and 802.3ad hashing method; "
"0 for layer 2 (default), 1 for layer 3+4, "
- "2 for layer 2+3");
+ "2 for layer 2+3, 3 for encap layer 2+3, "
+ "4 for encap layer 3+4");
module_param(arp_interval, int, 0);
MODULE_PARM_DESC(arp_interval, "arp interval in milliseconds");
module_param_array(arp_ip_target, charp, NULL, 0);
@@ -217,6 +219,8 @@ const struct bond_parm_tbl xmit_hashtype_tbl[] = {
{ "layer2", BOND_XMIT_POLICY_LAYER2},
{ "layer3+4", BOND_XMIT_POLICY_LAYER34},
{ "layer2+3", BOND_XMIT_POLICY_LAYER23},
+{ "encap2+3", BOND_XMIT_POLICY_ENCAP23},
+{ "encap3+4", BOND_XMIT_POLICY_ENCAP34},
{ NULL, -1},
};

@@ -3026,99 +3030,85 @@ static struct notifier_block bond_netdev_notifier = {

/*---------------------------- Hashing Policies -----------------------------*/

-/*
- * Hash for the output device based upon layer 2 data
- */
-static int bond_xmit_hash_policy_l2(struct sk_buff *skb, int count)
+/* L2 hash helper */
+static inline u32 bond_eth_hash(struct sk_buff *skb)
{
struct ethhdr *data = (struct ethhdr *)skb->data;

if (skb_headlen(skb) >= offsetof(struct ethhdr, h_proto))
- return (data->h_dest[5] ^ data->h_source[5]) % count;
+ return data->h_dest[5] ^ data->h_source[5];

return 0;
}

-/*
- * Hash for the output device based upon layer 2 and layer 3 data. If
- * the packet is not IP, fall back on bond_xmit_hash_policy_l2()
- */
-static int bond_xmit_hash_policy_l23(struct sk_buff *skb, int count)
+/* Extract the appropriate headers based on bond's xmit policy */
+static bool bond_flow_dissect(struct bonding *bond, struct sk_buff *skb,
+ struct flow_keys *fk)
{
- const struct ethhdr *data;
+ const struct ipv6hdr *iph6;
const struct iphdr *iph;
- const struct ipv6hdr *ipv6h;
- u32 v6hash;
- const __be32 *s, *d;
+ int noff, proto = -1;

- if (skb->protocol == htons(ETH_P_IP) &&
- pskb_network_may_pull(skb, sizeof(*iph))) {
+ if (bond->params.xmit_policy > BOND_XMIT_POLICY_LAYER23)
+ return skb_flow_dissect(skb, fk);
+
+ fk->ports = 0;
+ noff = skb_network_offset(skb);
+ if (skb->protocol == htons(ETH_P_IP)) {
+ if (!pskb_may_pull(skb, noff + sizeof(*iph)))
+ return false;
iph = ip_hdr(skb);
- data = (struct ethhdr *)skb->data;
- return ((ntohl(iph->saddr ^ iph->daddr) & 0xffff) ^
- (data->h_dest[5] ^ data->h_source[5])) % count;
- } else if (skb->protocol == htons(ETH_P_IPV6) &&
- pskb_network_may_pull(skb, sizeof(*ipv6h))) {
- ipv6h = ipv6_hdr(skb);
- data = (struct ethhdr *)skb->data;
- s = &ipv6h->saddr.s6_addr32[0];
- d = &ipv6h->daddr.s6_addr32[0];
- v6hash = (s[1] ^ d[1]) ^ (s[2] ^ d[2]) ^ (s[3] ^ d[3]);
- v6hash ^= (v6hash >> 24) ^ (v6hash >> 16) ^ (v6hash >> 8);
- return (v6hash ^ data->h_dest[5] ^ data->h_source[5]) % count;
- }
-
- return bond_xmit_hash_policy_l2(skb, count);
+ fk->src = iph->saddr;
+ fk->dst = iph->daddr;
+ noff += iph->ihl << 2;
+ if (!ip_is_fragment(iph))
+ proto = iph->protocol;
+ } else if (skb->protocol == htons(ETH_P_IPV6)) {
+ if (!pskb_may_pull(skb, noff + sizeof(*iph6)))
+ return false;
+ iph6 = ipv6_hdr(skb);
+ fk->src = (__force __be32)ipv6_addr_hash(&iph6->saddr);
+ fk->dst = (__force __be32)ipv6_addr_hash(&iph6->daddr);
+ noff += sizeof(*iph6);
+ proto = iph6->nexthdr;
+ } else {
+ return false;
+ }
+ if (bond->params.xmit_policy == BOND_XMIT_POLICY_LAYER34 && proto >= 0)
+ fk->ports = skb_flow_get_ports(skb, &noff, proto);
+
+ return true;
}

-/*
- * 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, fall back on bond_xmit_hash_policy_l2()
+/**
+ * bond_xmit_hash - generate a hash value based on the xmit policy
+ * @bond: bonding device
+ * @skb: buffer to use for headers
+ * @count: modulo value
+ *
+ * This function will extract the necessary headers from the skb buffer and use
+ * them to generate a hash based on the xmit_policy set in the bonding device
+ * which will be reduced modulo count before returning.
*/
-static int bond_xmit_hash_policy_l34(struct sk_buff *skb, int count)
+int bond_xmit_hash(struct bonding *bond, struct sk_buff *skb, int count)
{
- u32 layer4_xor = 0;
- const struct iphdr *iph;
- const struct ipv6hdr *ipv6h;
- const __be32 *s, *d;
- const __be16 *l4 = NULL;
- __be16 _l4[2];
- int noff = skb_network_offset(skb);
- int poff;
-
- if (skb->protocol == htons(ETH_P_IP) &&
- pskb_may_pull(skb, noff + sizeof(*iph))) {
- iph = ip_hdr(skb);
- poff = proto_ports_offset(iph->protocol);
+ struct flow_keys flow;
+ u32 hash;

- if (!ip_is_fragment(iph) && poff >= 0) {
- l4 = skb_header_pointer(skb, noff + (iph->ihl << 2) + poff,
- sizeof(_l4), &_l4);
- if (l4)
- layer4_xor = ntohs(l4[0] ^ l4[1]);
- }
- return (layer4_xor ^
- ((ntohl(iph->saddr ^ iph->daddr)) & 0xffff)) % count;
- } else if (skb->protocol == htons(ETH_P_IPV6) &&
- pskb_may_pull(skb, noff + sizeof(*ipv6h))) {
- ipv6h = ipv6_hdr(skb);
- poff = proto_ports_offset(ipv6h->nexthdr);
- if (poff >= 0) {
- l4 = skb_header_pointer(skb, noff + sizeof(*ipv6h) + poff,
- sizeof(_l4), &_l4);
- if (l4)
- layer4_xor = ntohs(l4[0] ^ l4[1]);
- }
- s = &ipv6h->saddr.s6_addr32[0];
- d = &ipv6h->daddr.s6_addr32[0];
- layer4_xor ^= (s[1] ^ d[1]) ^ (s[2] ^ d[2]) ^ (s[3] ^ d[3]);
- layer4_xor ^= (layer4_xor >> 24) ^ (layer4_xor >> 16) ^
- (layer4_xor >> 8);
- return layer4_xor % count;
- }
+ if (bond->params.xmit_policy == BOND_XMIT_POLICY_LAYER2 ||
+ !bond_flow_dissect(bond, skb, &flow))
+ return bond_eth_hash(skb) % count;
+
+ if (bond->params.xmit_policy == BOND_XMIT_POLICY_LAYER23 ||
+ bond->params.xmit_policy == BOND_XMIT_POLICY_ENCAP23)
+ hash = bond_eth_hash(skb);
+ else
+ hash = (__force u32)flow.ports;
+ hash ^= (__force u32)flow.dst ^ (__force u32)flow.src;
+ hash ^= (hash >> 16);
+ hash ^= (hash >> 8);

- return bond_xmit_hash_policy_l2(skb, count);
+ return hash % count;
}

/*-------------------------- Device entry points ----------------------------*/
@@ -3700,8 +3690,7 @@ static int bond_xmit_activebackup(struct sk_buff *skb, struct net_device *bond_d
return NETDEV_TX_OK;
}

-/*
- * In bond_xmit_xor() , we determine the output device by using a pre-
+/* In bond_xmit_xor() , we determine the output device by using a pre-
* determined xmit_hash_policy(), If the selected device is not enabled,
* find the next active slave.
*/
@@ -3709,8 +3698,7 @@ static int bond_xmit_xor(struct sk_buff *skb, struct net_device *bond_dev)
{
struct bonding *bond = netdev_priv(bond_dev);

- bond_xmit_slave_id(bond, skb,
- bond->xmit_hash_policy(skb, bond->slave_cnt));
+ bond_xmit_slave_id(bond, skb, bond_xmit_hash(bond, skb, bond->slave_cnt));

return NETDEV_TX_OK;
}
@@ -3746,22 +3734,6 @@ static int bond_xmit_broadcast(struct sk_buff *skb, struct net_device *bond_dev)

/*------------------------- 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;
- }
-}
-
/*
* Lookup the slave that corresponds to a qid
*/
@@ -3871,38 +3843,6 @@ static netdev_tx_t bond_start_xmit(struct sk_buff *skb, struct net_device *dev)
return ret;
}

-/*
- * set bond mode specific net device operations
- */
-void bond_set_mode_ops(struct bonding *bond, int mode)
-{
- struct net_device *bond_dev = bond->dev;
-
- switch (mode) {
- case BOND_MODE_ROUNDROBIN:
- break;
- case BOND_MODE_ACTIVEBACKUP:
- break;
- case BOND_MODE_XOR:
- bond_set_xmit_hash_policy(bond);
- break;
- case BOND_MODE_BROADCAST:
- break;
- case BOND_MODE_8023AD:
- bond_set_xmit_hash_policy(bond);
- break;
- case BOND_MODE_ALB:
- /* FALLTHRU */
- case BOND_MODE_TLB:
- break;
- default:
- /* Should never happen, mode already checked */
- pr_err("%s: Error: Unknown bonding mode %d\n",
- bond_dev->name, mode);
- break;
- }
-}
-
static int bond_ethtool_get_settings(struct net_device *bond_dev,
struct ethtool_cmd *ecmd)
{
@@ -4004,7 +3944,6 @@ static void bond_setup(struct net_device *bond_dev)
ether_setup(bond_dev);
bond_dev->netdev_ops = &bond_netdev_ops;
bond_dev->ethtool_ops = &bond_ethtool_ops;
- bond_set_mode_ops(bond, bond->params.mode);

bond_dev->destructor = bond_destructor;

diff --git a/drivers/net/bonding/bond_sysfs.c b/drivers/net/bonding/bond_sysfs.c
index c29b836..dba3b9b 100644
--- a/drivers/net/bonding/bond_sysfs.c
+++ b/drivers/net/bonding/bond_sysfs.c
@@ -352,7 +352,6 @@ static ssize_t bonding_store_mode(struct device *d,
/* don't cache arp_validate between modes */
bond->params.arp_validate = BOND_ARP_VALIDATE_NONE;
bond->params.mode = new_value;
- bond_set_mode_ops(bond, bond->params.mode);
pr_info("%s: setting mode to %s (%d).\n",
bond->dev->name, bond_mode_tbl[new_value].modename,
new_value);
@@ -392,7 +391,6 @@ static ssize_t bonding_store_xmit_hash(struct device *d,
ret = -EINVAL;
} else {
bond->params.xmit_policy = new_value;
- bond_set_mode_ops(bond, bond->params.mode);
pr_info("%s: setting xmit hash policy to %s (%d).\n",
bond->dev->name,
xmit_hashtype_tbl[new_value].modename, new_value);
diff --git a/drivers/net/bonding/bonding.h b/drivers/net/bonding/bonding.h
index 03cf3fd..4db9ec4 100644
--- a/drivers/net/bonding/bonding.h
+++ b/drivers/net/bonding/bonding.h
@@ -245,7 +245,6 @@ struct bonding {
char proc_file_name[IFNAMSIZ];
#endif /* CONFIG_PROC_FS */
struct list_head bond_list;
- int (*xmit_hash_policy)(struct sk_buff *, int);
u16 rr_tx_counter;
struct ad_bond_info ad_info;
struct alb_bond_info alb_info;
@@ -446,7 +445,7 @@ int bond_release(struct net_device *bond_dev, struct net_device *slave_dev);
void bond_mii_monitor(struct work_struct *);
void bond_loadbalance_arp_mon(struct work_struct *);
void bond_activebackup_arp_mon(struct work_struct *);
-void bond_set_mode_ops(struct bonding *bond, int mode);
+int bond_xmit_hash(struct bonding *bond, struct sk_buff *skb, int count);
int bond_parse_parm(const char *mode_arg, const struct bond_parm_tbl *tbl);
void bond_select_active_slave(struct bonding *bond);
void bond_change_active_slave(struct bonding *bond, struct slave *new_active);
diff --git a/include/uapi/linux/if_bonding.h b/include/uapi/linux/if_bonding.h
index a17edda..9635a62 100644
--- a/include/uapi/linux/if_bonding.h
+++ b/include/uapi/linux/if_bonding.h
@@ -91,6 +91,8 @@
#define BOND_XMIT_POLICY_LAYER2 0 /* layer 2 (MAC only), default */
#define BOND_XMIT_POLICY_LAYER34 1 /* layer 3+4 (IP ^ (TCP || UDP)) */
#define BOND_XMIT_POLICY_LAYER23 2 /* layer 2+3 (IP ^ MAC) */
+#define BOND_XMIT_POLICY_ENCAP23 3 /* encapsulated layer 2+3 */
+#define BOND_XMIT_POLICY_ENCAP34 4 /* encapsulated layer 3+4 */

typedef struct ifbond {
__s32 bond_mode;
--
1.8.1.4