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Commit 5ba24953 authored by Tom Herbert's avatar Tom Herbert Committed by David S. Miller
Browse files

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: default avatarTom Herbert <therbert@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ba418fa3

include/net/inet6_hashtables.h

+4 −1
Original line number Diff line number Diff line
@@ -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,

include/net/netfilter/nf_tproxy_core.h

+1 −0
Original line number Diff line number Diff line
@@ -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);

net/ipv6/inet6_connection_sock.c

+14 −5
Original line number Diff line number Diff line
@@ -32,6 +32,9 @@ int inet6_csk_bind_conflict(const struct sock *sk, 
{

	const struct sock *sk2;

	const struct hlist_node *node;

	int reuse = sk->sk_reuse;

	int reuseport = sk->sk_reuseport;

	int uid = sock_i_uid((struct sock *)sk);



	/* We must walk the whole port owner list in this case. -DaveM */

	/*
@@ -42,12 +45,18 @@ int inet6_csk_bind_conflict(const struct sock *sk, 
		if (sk != sk2 &&

		    (!sk->sk_bound_dev_if ||

		     !sk2->sk_bound_dev_if ||

		     sk->sk_bound_dev_if == sk2->sk_bound_dev_if) &&

		    (!sk->sk_reuse || !sk2->sk_reuse ||

		     sk->sk_bound_dev_if == sk2->sk_bound_dev_if)) {

			if ((!reuse || !sk2->sk_reuse ||

			     sk2->sk_state == TCP_LISTEN) &&

		     ipv6_rcv_saddr_equal(sk, sk2))

			    (!reuseport || !sk2->sk_reuseport ||

			     (sk2->sk_state != TCP_TIME_WAIT &&

			      !uid_eq(uid,

				      sock_i_uid((struct sock *)sk2))))) {

				if (ipv6_rcv_saddr_equal(sk, sk2))

					break;

			}

		}

	}



	return node != NULL;

}

net/ipv6/inet6_hashtables.c

+16 −3
Original line number Diff line number Diff line
@@ -158,25 +158,38 @@ static inline int compute_score(struct sock *sk, struct net *net, 
}



struct sock *inet6_lookup_listener(struct net *net,

		struct inet_hashinfo *hashinfo, const struct in6_addr *daddr,

		struct inet_hashinfo *hashinfo, const struct in6_addr *saddr,

		const __be16 sport, const struct in6_addr *daddr,

		const unsigned short hnum, const int dif)

{

	struct sock *sk;

	const struct hlist_nulls_node *node;

	struct sock *result;

	int score, hiscore;

	int score, hiscore, matches = 0, reuseport = 0;

	u32 phash = 0;

	unsigned int hash = inet_lhashfn(net, hnum);

	struct inet_listen_hashbucket *ilb = &hashinfo->listening_hash[hash];



	rcu_read_lock();

begin:

	result = NULL;

	hiscore = -1;

	hiscore = 0;

	sk_nulls_for_each(sk, node, &ilb->head) {

		score = compute_score(sk, net, hnum, daddr, dif);

		if (score > hiscore) {

			hiscore = score;

			result = sk;

			reuseport = sk->sk_reuseport;

			if (reuseport) {

				phash = inet6_ehashfn(net, daddr, hnum,

						      saddr, sport);

				matches = 1;

			}

		} else if (score == hiscore && reuseport) {

			matches++;

			if (((u64)phash * matches) >> 32 == 0)

				result = sk;

			phash = next_pseudo_random32(phash);

		}

	}

	/*

net/ipv6/tcp_ipv6.c

+3 −1
Original line number Diff line number Diff line
@@ -834,7 +834,8 @@ static void tcp_v6_send_reset(struct sock *sk, struct sk_buff *skb) 
		 * no RST generated if md5 hash doesn't match.

		 */

		sk1 = inet6_lookup_listener(dev_net(skb_dst(skb)->dev),

					   &tcp_hashinfo, &ipv6h->daddr,

					   &tcp_hashinfo, &ipv6h->saddr,

					   th->source, &ipv6h->daddr,

					   ntohs(th->source), inet6_iif(skb));

		if (!sk1)

			return;
@@ -1598,6 +1599,7 @@ static int tcp_v6_rcv(struct sk_buff *skb) 
		struct sock *sk2;



		sk2 = inet6_lookup_listener(dev_net(skb->dev), &tcp_hashinfo,

					    &ipv6_hdr(skb)->saddr, th->source,

					    &ipv6_hdr(skb)->daddr,

					    ntohs(th->dest), inet6_iif(skb));

		if (sk2 != NULL) {