tcp/dccp: install syn_recv requests into ehash table

In this patch, we insert request sockets into TCP/DCCP
regular ehash table (where ESTABLISHED and TIMEWAIT sockets
are) instead of using the per listener hash table.

ACK packets find SYN_RECV pseudo sockets without having
to find and lock the listener.

In nominal conditions, this halves pressure on listener lock.

Note that this will allow for SO_REUSEPORT refinements,
so that we can select a listener using cpu/numa affinities instead
of the prior 'consistent hash', since only SYN packets will
apply this selection logic.

We will shrink listen_sock in the following patch to ease
code review.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Ying Cai <ycai@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 88 deletions

diff --git a/net/ipv4/inet_diag.c b/net/ipv4/inet_diag.c
index 0ac1d68dc8a6..ab9f8a66615d 100644
--- a/net/ipv4/inet_diag.c
+++ b/net/ipv4/inet_diag.c
@@ -730,91 +730,21 @@ static void twsk_build_assert(void)
 #endif
 }
 
-static int inet_diag_dump_reqs(struct sk_buff *skb, struct sock *sk,
-			       struct netlink_callback *cb,
-			       const struct inet_diag_req_v2 *r,
-			       const struct nlattr *bc)
-{
-	struct inet_connection_sock *icsk = inet_csk(sk);
-	struct inet_sock *inet = inet_sk(sk);
-	struct inet_diag_entry entry;
-	int j, s_j, reqnum, s_reqnum;
-	struct listen_sock *lopt;
-	int err = 0;
-
-	s_j = cb->args[3];
-	s_reqnum = cb->args[4];
-
-	if (s_j > 0)
-		s_j--;
-
-	entry.family = sk->sk_family;
-
-	spin_lock(&icsk->icsk_accept_queue.syn_wait_lock);
-
-	lopt = icsk->icsk_accept_queue.listen_opt;
-	if (!lopt || !reqsk_queue_len(&icsk->icsk_accept_queue))
-		goto out;
-
-	if (bc) {
-		entry.sport = inet->inet_num;
-		entry.userlocks = sk->sk_userlocks;
-	}
-
-	for (j = s_j; j < lopt->nr_table_entries; j++) {
-		struct request_sock *req, *head = lopt->syn_table[j];
-
-		reqnum = 0;
-		for (req = head; req; reqnum++, req = req->dl_next) {
-			struct inet_request_sock *ireq = inet_rsk(req);
-
-			if (reqnum < s_reqnum)
-				continue;
-			if (r->id.idiag_dport != ireq->ir_rmt_port &&
-			    r->id.idiag_dport)
-				continue;
-
-			if (bc) {
-				/* Note: entry.sport and entry.userlocks are already set */
-				entry_fill_addrs(&entry, req_to_sk(req));
-				entry.dport = ntohs(ireq->ir_rmt_port);
-
-				if (!inet_diag_bc_run(bc, &entry))
-					continue;
-			}
-
-			err = inet_req_diag_fill(req_to_sk(req), skb,
-						 NETLINK_CB(cb->skb).portid,
-						 cb->nlh->nlmsg_seq,
-						 NLM_F_MULTI, cb->nlh);
-			if (err < 0) {
-				cb->args[3] = j + 1;
-				cb->args[4] = reqnum;
-				goto out;
-			}
-		}
-
-		s_reqnum = 0;
-	}
-
-out:
-	spin_unlock(&icsk->icsk_accept_queue.syn_wait_lock);
-
-	return err;
-}
-
 void inet_diag_dump_icsk(struct inet_hashinfo *hashinfo, struct sk_buff *skb,
 			 struct netlink_callback *cb,
 			 const struct inet_diag_req_v2 *r, struct nlattr *bc)
 {
 	struct net *net = sock_net(skb->sk);
 	int i, num, s_i, s_num;
+	u32 idiag_states = r->idiag_states;
 
+	if (idiag_states & TCPF_SYN_RECV)
+		idiag_states |= TCPF_NEW_SYN_RECV;
 	s_i = cb->args[1];
 	s_num = num = cb->args[2];
 
 	if (cb->args[0] == 0) {
-		if (!(r->idiag_states & (TCPF_LISTEN | TCPF_SYN_RECV)))
+		if (!(idiag_states & TCPF_LISTEN))
 			goto skip_listen_ht;
 
 		for (i = s_i; i < INET_LHTABLE_SIZE; i++) {
@@ -844,21 +774,11 @@ void inet_diag_dump_icsk(struct inet_hashinfo *hashinfo, struct sk_buff *skb,
 				    r->id.idiag_sport)
 					goto next_listen;
 
-				if (!(r->idiag_states & TCPF_LISTEN) ||
-				    r->id.idiag_dport ||
+				if (r->id.idiag_dport ||
 				    cb->args[3] > 0)
-					goto syn_recv;
-
-				if (inet_csk_diag_dump(sk, skb, cb, r, bc) < 0) {
-					spin_unlock_bh(&ilb->lock);
-					goto done;
-				}
-
-syn_recv:
-				if (!(r->idiag_states & TCPF_SYN_RECV))
 					goto next_listen;
 
-				if (inet_diag_dump_reqs(skb, sk, cb, r, bc) < 0) {
+				if (inet_csk_diag_dump(sk, skb, cb, r, bc) < 0) {
 					spin_unlock_bh(&ilb->lock);
 					goto done;
 				}
@@ -879,7 +799,7 @@ skip_listen_ht:
 		s_i = num = s_num = 0;
 	}
 
-	if (!(r->idiag_states & ~(TCPF_LISTEN | TCPF_SYN_RECV)))
+	if (!(idiag_states & ~TCPF_LISTEN))
 		goto out;
 
 	for (i = s_i; i <= hashinfo->ehash_mask; i++) {
@@ -906,7 +826,7 @@ skip_listen_ht:
 				goto next_normal;
 			state = (sk->sk_state == TCP_TIME_WAIT) ?
 				inet_twsk(sk)->tw_substate : sk->sk_state;
-			if (!(r->idiag_states & (1 << state)))
+			if (!(idiag_states & (1 << state)))
 				goto next_normal;
 			if (r->sdiag_family != AF_UNSPEC &&
 			    sk->sk_family != r->sdiag_family)