From 08dcdbf6a7b9d14c2302c5bd0c5390ddf122f664 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 21 Feb 2013 12:18:52 +0000 Subject: ipv6: use a stronger hash for tcp It looks like its possible to open thousands of TCP IPv6 sessions on a server, all landing in a single slot of TCP hash table. Incoming packets have to lookup sockets in a very long list. We should hash all bits from foreign IPv6 addresses, using a salt and hash mix, not a simple XOR. inet6_ehashfn() can also separately use the ports, instead of xoring them. Reported-by: Neal Cardwell Signed-off-by: Eric Dumazet Cc: Yuchung Cheng Signed-off-by: David S. Miller --- include/net/inet6_hashtables.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'include/net/inet6_hashtables.h') diff --git a/include/net/inet6_hashtables.h b/include/net/inet6_hashtables.h index 7ca75cbbf75e..fd4ee016ba5c 100644 --- a/include/net/inet6_hashtables.h +++ b/include/net/inet6_hashtables.h @@ -28,16 +28,16 @@ struct inet_hashinfo; -/* I have no idea if this is a good hash for v6 or not. -DaveM */ static inline unsigned int inet6_ehashfn(struct net *net, const struct in6_addr *laddr, const u16 lport, const struct in6_addr *faddr, const __be16 fport) { - u32 ports = (lport ^ (__force u16)fport); + u32 ports = (((u32)lport) << 16) | (__force u32)fport; return jhash_3words((__force u32)laddr->s6_addr32[3], - (__force u32)faddr->s6_addr32[3], - ports, inet_ehash_secret + net_hash_mix(net)); + ipv6_addr_jhash(faddr), + ports, + inet_ehash_secret + net_hash_mix(net)); } static inline int inet6_sk_ehashfn(const struct sock *sk) -- cgit v1.2.3