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bonding: do not discard lowest hash bit for non layer3+4 hashing 

Commit b5f862180d was introduced to discard lowest hash bit for layer3+4 hashing
but it also removes last bit from non layer3+4 hashing

Below script shows layer2+3 hashing will result in same slave to be used with above commit.
$ cat hash.py
#/usr/bin/python3.6

h_dests=[0xa0, 0xa1]
h_source=0xe3
hproto=0x8
saddr=0x1e7aa8c0
daddr=0x17aa8c0

for h_dest in h_dests:
    hash = (h_dest ^ h_source ^ hproto ^ saddr ^ daddr)
    hash ^= hash >> 16
    hash ^= hash >> 8
    print(hash)

print("with last bit removed")
for h_dest in h_dests:
    hash = (h_dest ^ h_source ^ hproto ^ saddr ^ daddr)
    hash ^= hash >> 16
    hash ^= hash >> 8
    hash = hash >> 1
    print(hash)

Output:
$ python3.6 hash.py
522133332
522133333   <-------------- will result in both slaves being used

with last bit removed
261066666
261066666   <-------------- only single slave used

Signed-off-by: suresh kumar <suresh2514@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
suresh kumar 2022-04-16 16:44:10 +05:30 committed by David S. Miller
parent d08ed85256
commit 49aefd1317
1 changed files with 9 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
drivers/net/bonding/bond_main.c
View File

@ -4027,14 +4027,19 @@ static bool bond_flow_dissect(struct bonding *bond, struct sk_buff *skb, const v
return true;
}
static u32 bond_ip_hash(u32 hash, struct flow_keys *flow)
static u32 bond_ip_hash(u32 hash, struct flow_keys *flow, int xmit_policy)
{
hash ^= (__force u32)flow_get_u32_dst(flow) ^
(__force u32)flow_get_u32_src(flow);
hash ^= (hash >> 16);
hash ^= (hash >> 8);
/* discard lowest hash bit to deal with the common even ports pattern */
return hash >> 1;
if (xmit_policy == BOND_XMIT_POLICY_LAYER34 ||
xmit_policy == BOND_XMIT_POLICY_ENCAP34)
return hash >> 1;
return hash;
}
/* Generate hash based on xmit policy. If @skb is given it is used to linearize
@ -4064,7 +4069,7 @@ static u32 __bond_xmit_hash(struct bonding *bond, struct sk_buff *skb, const voi
memcpy(&hash, &flow.ports.ports, sizeof(hash));
}
return bond_ip_hash(hash, &flow);
return bond_ip_hash(hash, &flow, bond->params.xmit_policy);
}
/**
@ -5259,7 +5264,7 @@ static u32 bond_sk_hash_l34(struct sock *sk)
/* L4 */
memcpy(&hash, &flow.ports.ports, sizeof(hash));
/* L3 */
return bond_ip_hash(hash, &flow);
return bond_ip_hash(hash, &flow, BOND_XMIT_POLICY_LAYER34);
}
static struct net_device *__bond_sk_get_lower_dev(struct bonding *bond,