From 72289b96c943757220ccc681fe2e22b46e21aced Mon Sep 17 00:00:00 2001 From: Tom Herbert Date: Tue, 22 Jan 2013 09:50:44 +0000 Subject: [PATCH] soreuseport: UDP/IPv6 implementation MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Motivation for soreuseport would be something like a DNS server.  An alternative would be to recv on the same socket from multiple threads. As in the case of TCP, the load across these threads tends to be disproportionate and we also see a lot of contection on the socket lock. Note that SO_REUSEADDR already allows multiple UDP sockets to bind to the same port, however there is no provision to prevent hijacking and nothing to distribute packets across all the sockets sharing the same bound port.  This patch does not change the semantics of SO_REUSEADDR, but provides usable functionality of it for unicast. Signed-off-by: Tom Herbert Signed-off-by: David S. Miller --- net/ipv6/udp.c | 30 +++++++++++++++++++++++++++--- 1 file changed, 27 insertions(+), 3 deletions(-) diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c index 1afb635d9b5..cb5bf497c09 100644 --- a/net/ipv6/udp.c +++ b/net/ipv6/udp.c @@ -45,6 +45,7 @@ #include #include #include +#include #include #include @@ -203,7 +204,8 @@ static struct sock *udp6_lib_lookup2(struct net *net, { struct sock *sk, *result; struct hlist_nulls_node *node; - int score, badness; + int score, badness, matches = 0, reuseport = 0; + u32 hash = 0; begin: result = NULL; @@ -214,8 +216,18 @@ begin: if (score > badness) { result = sk; badness = score; - if (score == SCORE2_MAX) + reuseport = sk->sk_reuseport; + if (reuseport) { + hash = inet6_ehashfn(net, daddr, hnum, + saddr, sport); + matches = 1; + } else if (score == SCORE2_MAX) goto exact_match; + } else if (score == badness && reuseport) { + matches++; + if (((u64)hash * matches) >> 32 == 0) + result = sk; + hash = next_pseudo_random32(hash); } } /* @@ -249,7 +261,8 @@ struct sock *__udp6_lib_lookup(struct net *net, unsigned short hnum = ntohs(dport); unsigned int hash2, slot2, slot = udp_hashfn(net, hnum, udptable->mask); struct udp_hslot *hslot2, *hslot = &udptable->hash[slot]; - int score, badness; + int score, badness, matches = 0, reuseport = 0; + u32 hash = 0; rcu_read_lock(); if (hslot->count > 10) { @@ -284,6 +297,17 @@ begin: if (score > badness) { result = sk; badness = score; + reuseport = sk->sk_reuseport; + if (reuseport) { + hash = inet6_ehashfn(net, daddr, hnum, + saddr, sport); + matches = 1; + } + } else if (score == badness && reuseport) { + matches++; + if (((u64)hash * matches) >> 32 == 0) + result = sk; + hash = next_pseudo_random32(hash); } } /* -- 2.41.0