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>
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index d0670f0..8bb623d 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -59,6 +59,8 @@
struct sock *sk2;
struct hlist_node *node;
int reuse = sk->sk_reuse;
+ int reuseport = sk->sk_reuseport;
+ kuid_t uid = sock_i_uid((struct sock *)sk);
/*
* Unlike other sk lookup places we do not check
@@ -73,8 +75,11 @@
(!sk->sk_bound_dev_if ||
!sk2->sk_bound_dev_if ||
sk->sk_bound_dev_if == sk2->sk_bound_dev_if)) {
- if (!reuse || !sk2->sk_reuse ||
- sk2->sk_state == TCP_LISTEN) {
+ if ((!reuse || !sk2->sk_reuse ||
+ sk2->sk_state == TCP_LISTEN) &&
+ (!reuseport || !sk2->sk_reuseport ||
+ (sk2->sk_state != TCP_TIME_WAIT &&
+ !uid_eq(uid, sock_i_uid(sk2))))) {
const __be32 sk2_rcv_saddr = sk_rcv_saddr(sk2);
if (!sk2_rcv_saddr || !sk_rcv_saddr(sk) ||
sk2_rcv_saddr == sk_rcv_saddr(sk))
@@ -106,6 +111,7 @@
int ret, attempts = 5;
struct net *net = sock_net(sk);
int smallest_size = -1, smallest_rover;
+ kuid_t uid = sock_i_uid(sk);
local_bh_disable();
if (!snum) {
@@ -125,9 +131,12 @@
spin_lock(&head->lock);
inet_bind_bucket_for_each(tb, node, &head->chain)
if (net_eq(ib_net(tb), net) && tb->port == rover) {
- if (tb->fastreuse > 0 &&
- sk->sk_reuse &&
- sk->sk_state != TCP_LISTEN &&
+ if (((tb->fastreuse > 0 &&
+ sk->sk_reuse &&
+ sk->sk_state != TCP_LISTEN) ||
+ (tb->fastreuseport > 0 &&
+ sk->sk_reuseport &&
+ uid_eq(tb->fastuid, uid))) &&
(tb->num_owners < smallest_size || smallest_size == -1)) {
smallest_size = tb->num_owners;
smallest_rover = rover;
@@ -185,14 +194,17 @@
if (sk->sk_reuse == SK_FORCE_REUSE)
goto success;
- if (tb->fastreuse > 0 &&
- sk->sk_reuse && sk->sk_state != TCP_LISTEN &&
+ if (((tb->fastreuse > 0 &&
+ sk->sk_reuse && sk->sk_state != TCP_LISTEN) ||
+ (tb->fastreuseport > 0 &&
+ sk->sk_reuseport && uid_eq(tb->fastuid, uid))) &&
smallest_size == -1) {
goto success;
} else {
ret = 1;
if (inet_csk(sk)->icsk_af_ops->bind_conflict(sk, tb, true)) {
- if (sk->sk_reuse && sk->sk_state != TCP_LISTEN &&
+ if (((sk->sk_reuse && sk->sk_state != TCP_LISTEN) ||
+ (sk->sk_reuseport && uid_eq(tb->fastuid, uid))) &&
smallest_size != -1 && --attempts >= 0) {
spin_unlock(&head->lock);
goto again;
@@ -212,9 +224,23 @@
tb->fastreuse = 1;
else
tb->fastreuse = 0;
- } else if (tb->fastreuse &&
- (!sk->sk_reuse || sk->sk_state == TCP_LISTEN))
- tb->fastreuse = 0;
+ if (sk->sk_reuseport) {
+ tb->fastreuseport = 1;
+ tb->fastuid = uid;
+ } else {
+ tb->fastreuseport = 0;
+ tb->fastuid = 0;
+ }
+ } else {
+ if (tb->fastreuse &&
+ (!sk->sk_reuse || sk->sk_state == TCP_LISTEN))
+ tb->fastreuse = 0;
+ if (tb->fastreuseport &&
+ (!sk->sk_reuseport || !uid_eq(tb->fastuid, uid))) {
+ tb->fastreuseport = 0;
+ tb->fastuid = 0;
+ }
+ }
success:
if (!inet_csk(sk)->icsk_bind_hash)
inet_bind_hash(sk, tb, snum);