soreuseport: TCP/IPv4 implementation
Allow multiple listener sockets to bind to the same port. Motivation for soresuseport 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>
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@ -81,7 +81,9 @@ struct inet_bind_bucket {
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struct net *ib_net;
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#endif
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unsigned short port;
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signed short fastreuse;
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signed char fastreuse;
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signed char fastreuseport;
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kuid_t fastuid;
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int num_owners;
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struct hlist_node node;
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struct hlist_head owners;
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@ -257,15 +259,19 @@ extern void inet_unhash(struct sock *sk);
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extern struct sock *__inet_lookup_listener(struct net *net,
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struct inet_hashinfo *hashinfo,
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const __be32 saddr,
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const __be16 sport,
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const __be32 daddr,
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const unsigned short hnum,
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const int dif);
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static inline struct sock *inet_lookup_listener(struct net *net,
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struct inet_hashinfo *hashinfo,
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__be32 saddr, __be16 sport,
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__be32 daddr, __be16 dport, int dif)
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{
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return __inet_lookup_listener(net, hashinfo, daddr, ntohs(dport), dif);
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return __inet_lookup_listener(net, hashinfo, saddr, sport,
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daddr, ntohs(dport), dif);
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}
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/* Socket demux engine toys. */
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@ -358,7 +364,8 @@ static inline struct sock *__inet_lookup(struct net *net,
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struct sock *sk = __inet_lookup_established(net, hashinfo,
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saddr, sport, daddr, hnum, dif);
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return sk ? : __inet_lookup_listener(net, hashinfo, daddr, hnum, dif);
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return sk ? : __inet_lookup_listener(net, hashinfo, saddr, sport,
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daddr, hnum, dif);
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}
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static inline struct sock *inet_lookup(struct net *net,
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@ -82,6 +82,7 @@ nf_tproxy_get_sock_v4(struct net *net, const u8 protocol,
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break;
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case NFT_LOOKUP_LISTENER:
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sk = inet_lookup_listener(net, &tcp_hashinfo,
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saddr, sport,
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daddr, dport,
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in->ifindex);
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@ -59,6 +59,8 @@ int inet_csk_bind_conflict(const struct sock *sk,
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struct sock *sk2;
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struct hlist_node *node;
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int reuse = sk->sk_reuse;
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int reuseport = sk->sk_reuseport;
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kuid_t uid = sock_i_uid((struct sock *)sk);
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/*
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* Unlike other sk lookup places we do not check
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@ -73,8 +75,11 @@ int inet_csk_bind_conflict(const struct sock *sk,
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(!sk->sk_bound_dev_if ||
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!sk2->sk_bound_dev_if ||
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sk->sk_bound_dev_if == sk2->sk_bound_dev_if)) {
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if (!reuse || !sk2->sk_reuse ||
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sk2->sk_state == TCP_LISTEN) {
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if ((!reuse || !sk2->sk_reuse ||
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sk2->sk_state == TCP_LISTEN) &&
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(!reuseport || !sk2->sk_reuseport ||
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(sk2->sk_state != TCP_TIME_WAIT &&
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!uid_eq(uid, sock_i_uid(sk2))))) {
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const __be32 sk2_rcv_saddr = sk_rcv_saddr(sk2);
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if (!sk2_rcv_saddr || !sk_rcv_saddr(sk) ||
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sk2_rcv_saddr == sk_rcv_saddr(sk))
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@ -106,6 +111,7 @@ int inet_csk_get_port(struct sock *sk, unsigned short snum)
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int ret, attempts = 5;
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struct net *net = sock_net(sk);
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int smallest_size = -1, smallest_rover;
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kuid_t uid = sock_i_uid(sk);
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local_bh_disable();
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if (!snum) {
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@ -125,9 +131,12 @@ again:
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spin_lock(&head->lock);
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inet_bind_bucket_for_each(tb, node, &head->chain)
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if (net_eq(ib_net(tb), net) && tb->port == rover) {
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if (tb->fastreuse > 0 &&
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sk->sk_reuse &&
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sk->sk_state != TCP_LISTEN &&
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if (((tb->fastreuse > 0 &&
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sk->sk_reuse &&
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sk->sk_state != TCP_LISTEN) ||
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(tb->fastreuseport > 0 &&
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sk->sk_reuseport &&
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uid_eq(tb->fastuid, uid))) &&
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(tb->num_owners < smallest_size || smallest_size == -1)) {
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smallest_size = tb->num_owners;
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smallest_rover = rover;
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@ -185,14 +194,17 @@ tb_found:
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if (sk->sk_reuse == SK_FORCE_REUSE)
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goto success;
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if (tb->fastreuse > 0 &&
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sk->sk_reuse && sk->sk_state != TCP_LISTEN &&
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if (((tb->fastreuse > 0 &&
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sk->sk_reuse && sk->sk_state != TCP_LISTEN) ||
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(tb->fastreuseport > 0 &&
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sk->sk_reuseport && uid_eq(tb->fastuid, uid))) &&
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smallest_size == -1) {
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goto success;
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} else {
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ret = 1;
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if (inet_csk(sk)->icsk_af_ops->bind_conflict(sk, tb, true)) {
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if (sk->sk_reuse && sk->sk_state != TCP_LISTEN &&
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if (((sk->sk_reuse && sk->sk_state != TCP_LISTEN) ||
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(sk->sk_reuseport && uid_eq(tb->fastuid, uid))) &&
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smallest_size != -1 && --attempts >= 0) {
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spin_unlock(&head->lock);
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goto again;
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@ -212,9 +224,23 @@ tb_not_found:
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tb->fastreuse = 1;
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else
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tb->fastreuse = 0;
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} else if (tb->fastreuse &&
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(!sk->sk_reuse || sk->sk_state == TCP_LISTEN))
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tb->fastreuse = 0;
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if (sk->sk_reuseport) {
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tb->fastreuseport = 1;
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tb->fastuid = uid;
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} else {
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tb->fastreuseport = 0;
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tb->fastuid = 0;
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}
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} else {
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if (tb->fastreuse &&
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(!sk->sk_reuse || sk->sk_state == TCP_LISTEN))
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tb->fastreuse = 0;
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if (tb->fastreuseport &&
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(!sk->sk_reuseport || !uid_eq(tb->fastuid, uid))) {
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tb->fastreuseport = 0;
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tb->fastuid = 0;
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}
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}
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success:
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if (!inet_csk(sk)->icsk_bind_hash)
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inet_bind_hash(sk, tb, snum);
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@ -39,6 +39,7 @@ struct inet_bind_bucket *inet_bind_bucket_create(struct kmem_cache *cachep,
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write_pnet(&tb->ib_net, hold_net(net));
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tb->port = snum;
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tb->fastreuse = 0;
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tb->fastreuseport = 0;
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tb->num_owners = 0;
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INIT_HLIST_HEAD(&tb->owners);
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hlist_add_head(&tb->node, &head->chain);
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@ -151,16 +152,16 @@ static inline int compute_score(struct sock *sk, struct net *net,
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if (net_eq(sock_net(sk), net) && inet->inet_num == hnum &&
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!ipv6_only_sock(sk)) {
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__be32 rcv_saddr = inet->inet_rcv_saddr;
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score = sk->sk_family == PF_INET ? 1 : 0;
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score = sk->sk_family == PF_INET ? 2 : 1;
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if (rcv_saddr) {
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if (rcv_saddr != daddr)
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return -1;
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score += 2;
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score += 4;
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}
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if (sk->sk_bound_dev_if) {
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if (sk->sk_bound_dev_if != dif)
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return -1;
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score += 2;
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score += 4;
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}
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}
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return score;
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@ -176,6 +177,7 @@ static inline int compute_score(struct sock *sk, struct net *net,
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struct sock *__inet_lookup_listener(struct net *net,
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struct inet_hashinfo *hashinfo,
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const __be32 saddr, __be16 sport,
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const __be32 daddr, const unsigned short hnum,
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const int dif)
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{
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@ -183,17 +185,29 @@ struct sock *__inet_lookup_listener(struct net *net,
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struct hlist_nulls_node *node;
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unsigned int hash = inet_lhashfn(net, hnum);
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struct inet_listen_hashbucket *ilb = &hashinfo->listening_hash[hash];
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int score, hiscore;
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int score, hiscore, matches = 0, reuseport = 0;
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u32 phash = 0;
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rcu_read_lock();
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begin:
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result = NULL;
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hiscore = -1;
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hiscore = 0;
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sk_nulls_for_each_rcu(sk, node, &ilb->head) {
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score = compute_score(sk, net, hnum, daddr, dif);
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if (score > hiscore) {
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result = sk;
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hiscore = score;
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reuseport = sk->sk_reuseport;
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if (reuseport) {
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phash = inet_ehashfn(net, daddr, hnum,
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saddr, sport);
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matches = 1;
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}
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} else if (score == hiscore && reuseport) {
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matches++;
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if (((u64)phash * matches) >> 32 == 0)
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result = sk;
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phash = next_pseudo_random32(phash);
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}
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}
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/*
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inet_bind_bucket_for_each(tb, node, &head->chain) {
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if (net_eq(ib_net(tb), net) &&
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tb->port == port) {
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if (tb->fastreuse >= 0)
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if (tb->fastreuse >= 0 ||
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tb->fastreuseport >= 0)
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goto next_port;
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WARN_ON(hlist_empty(&tb->owners));
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if (!check_established(death_row, sk,
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break;
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}
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tb->fastreuse = -1;
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tb->fastreuseport = -1;
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goto ok;
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next_port:
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@ -657,7 +657,8 @@ static void tcp_v4_send_reset(struct sock *sk, struct sk_buff *skb)
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* no RST generated if md5 hash doesn't match.
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*/
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sk1 = __inet_lookup_listener(dev_net(skb_dst(skb)->dev),
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&tcp_hashinfo, ip_hdr(skb)->daddr,
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&tcp_hashinfo, ip_hdr(skb)->saddr,
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th->source, ip_hdr(skb)->daddr,
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ntohs(th->source), inet_iif(skb));
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/* don't send rst if it can't find key */
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if (!sk1)
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case TCP_TW_SYN: {
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struct sock *sk2 = inet_lookup_listener(dev_net(skb->dev),
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&tcp_hashinfo,
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iph->saddr, th->source,
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iph->daddr, th->dest,
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inet_iif(skb));
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if (sk2) {
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