soreuseport: TCP/IPv6 implementation

Motivation for soreuseport would be something like a web server
binding to port 80 running with multiple threads, where each thread
might have it's own listener socket.  This could be done as an
alternative to other models: 1) have one listener thread which
dispatches completed connections to workers. 2) accept on a single
listener socket from multiple threads.  In case #1 the listener thread
can easily become the bottleneck with high connection turn-over rate.
In case #2, the proportion of connections accepted per thread tends
to be uneven under high connection load (assuming simple event loop:
while (1) { accept(); process() }, wakeup does not promote fairness
among the sockets.  We have seen the  disproportion to be as high
as 3:1 ratio between thread accepting most connections and the one
accepting the fewest.  With so_reusport the distribution is
uniform.

Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 5 insertions, 1 deletions

diff --git a/include/net/inet6_hashtables.h b/include/net/inet6_hashtables.h
index 9e34c877a770..7ca75cbbf75e 100644
--- a/include/net/inet6_hashtables.h
+++ b/include/net/inet6_hashtables.h
@@ -71,6 +71,8 @@ extern struct sock *__inet6_lookup_established(struct net *net,
 
 extern struct sock *inet6_lookup_listener(struct net *net,
                                           struct inet_hashinfo *hashinfo,
+                                          const struct in6_addr *saddr,
+                                          const __be16 sport,
                                           const struct in6_addr *daddr,
                                           const unsigned short hnum,
                                           const int dif);
@@ -88,7 +90,8 @@ static inline struct sock *__inet6_lookup(struct net *net,
         if (sk)
                 return sk;
 
-        return inet6_lookup_listener(net, hashinfo, daddr, hnum, dif);
+        return inet6_lookup_listener(net, hashinfo, saddr, sport,
+                                     daddr, hnum, dif);
 }
 
 static inline struct sock *__inet6_lookup_skb(struct inet_hashinfo *hashinfo,
diff --git a/include/net/netfilter/nf_tproxy_core.h b/include/net/netfilter/nf_tproxy_core.h
index 193796445642..36d9379d4c4b 100644
--- a/include/net/netfilter/nf_tproxy_core.h
+++ b/include/net/netfilter/nf_tproxy_core.h
@@ -152,6 +152,7 @@ nf_tproxy_get_sock_v6(struct net *net, const u8 protocol,
                         break;
                 case NFT_LOOKUP_LISTENER:
                         sk = inet6_lookup_listener(net, &tcp_hashinfo,
+                                                   saddr, sport,
                                                    daddr, ntohs(dport),
                                                    in->ifindex);