inet: drop prev pointer handling in request sock

When request sock are put in ehash table, the whole notion
of having a previous request to update dl_next is pointless.

Also, following patch will get rid of big purge timer,
so we want to delete a request sock without holding listener lock.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 23 insertions, 23 deletions

diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index f0f91858aecf..4f57a017928c 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -480,18 +480,17 @@ static inline u32 inet_synq_hash(const __be32 raddr, const __be16 rport,
 #endif
 
 struct request_sock *inet_csk_search_req(const struct sock *sk,
-					 struct request_sock ***prevp,
 					 const __be16 rport, const __be32 raddr,
 					 const __be32 laddr)
 {
 	const struct inet_connection_sock *icsk = inet_csk(sk);
 	struct listen_sock *lopt = icsk->icsk_accept_queue.listen_opt;
-	struct request_sock *req, **prev;
+	struct request_sock *req;
 
-	for (prev = &lopt->syn_table[inet_synq_hash(raddr, rport, lopt->hash_rnd,
-						    lopt->nr_table_entries)];
-	     (req = *prev) != NULL;
-	     prev = &req->dl_next) {
+	for (req = lopt->syn_table[inet_synq_hash(raddr, rport, lopt->hash_rnd,
+						  lopt->nr_table_entries)];
+	     req != NULL;
+	     req = req->dl_next) {
 		const struct inet_request_sock *ireq = inet_rsk(req);
 
 		if (ireq->ir_rmt_port == rport &&
@@ -499,7 +498,6 @@ struct request_sock *inet_csk_search_req(const struct sock *sk,
 		    ireq->ir_loc_addr == laddr &&
 		    AF_INET_FAMILY(req->rsk_ops->family)) {
 			WARN_ON(req->sk);
-			*prevp = prev;
 			break;
 		}
 	}
@@ -610,7 +608,10 @@ void inet_csk_reqsk_queue_prune(struct sock *parent,
 	i = lopt->clock_hand;
 
 	do {
-		reqp=&lopt->syn_table[i];
+		reqp = &lopt->syn_table[i];
+		if (!*reqp)
+			goto next_bucket;
+		write_lock(&queue->syn_wait_lock);
 		while ((req = *reqp) != NULL) {
 			if (time_after_eq(now, req->expires)) {
 				int expire = 0, resend = 0;
@@ -635,14 +636,15 @@ void inet_csk_reqsk_queue_prune(struct sock *parent,
 				}
 
 				/* Drop this request */
-				inet_csk_reqsk_queue_unlink(parent, req, reqp);
+				*reqp = req->dl_next;
 				reqsk_queue_removed(queue, req);
 				reqsk_put(req);
 				continue;
 			}
 			reqp = &req->dl_next;
 		}
-
+		write_unlock(&queue->syn_wait_lock);
+next_bucket:
 		i = (i + 1) & (lopt->nr_table_entries - 1);
 
 	} while (--budget > 0);
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 1dfbaee3554e..95caea707f54 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -5694,7 +5694,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
 		WARN_ON_ONCE(sk->sk_state != TCP_SYN_RECV &&
 		    sk->sk_state != TCP_FIN_WAIT1);
 
-		if (tcp_check_req(sk, skb, req, NULL, true) == NULL)
+		if (tcp_check_req(sk, skb, req, true) == NULL)
 			goto discard;
 	}
 
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index ddd0b1f25b96..19c3770f1e97 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -458,12 +458,12 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
 	}
 
 	switch (sk->sk_state) {
-		struct request_sock *req, **prev;
+		struct request_sock *req;
 	case TCP_LISTEN:
 		if (sock_owned_by_user(sk))
 			goto out;
 
-		req = inet_csk_search_req(sk, &prev, th->dest,
+		req = inet_csk_search_req(sk, th->dest,
 					  iph->daddr, iph->saddr);
 		if (!req)
 			goto out;
@@ -484,7 +484,7 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
 		 * created socket, and POSIX does not want network
 		 * errors returned from accept().
 		 */
-		inet_csk_reqsk_queue_drop(sk, req, prev);
+		inet_csk_reqsk_queue_drop(sk, req);
 		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
 		goto out;
 
@@ -1392,15 +1392,14 @@ EXPORT_SYMBOL(tcp_v4_syn_recv_sock);
 
 static struct sock *tcp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
 {
-	struct tcphdr *th = tcp_hdr(skb);
+	const struct tcphdr *th = tcp_hdr(skb);
 	const struct iphdr *iph = ip_hdr(skb);
+	struct request_sock *req;
 	struct sock *nsk;
-	struct request_sock **prev;
-	/* Find possible connection requests. */
-	struct request_sock *req = inet_csk_search_req(sk, &prev, th->source,
-						       iph->saddr, iph->daddr);
+
+	req = inet_csk_search_req(sk, th->source, iph->saddr, iph->daddr);
 	if (req)
-		return tcp_check_req(sk, skb, req, prev, false);
+		return tcp_check_req(sk, skb, req, false);
 
 	nsk = inet_lookup_established(sock_net(sk), &tcp_hashinfo, iph->saddr,
 			th->source, iph->daddr, th->dest, inet_iif(skb));
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index dd11ac7798c6..848bcab358e4 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -572,7 +572,6 @@ EXPORT_SYMBOL(tcp_create_openreq_child);
 
 struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
 			   struct request_sock *req,
-			   struct request_sock **prev,
 			   bool fastopen)
 {
 	struct tcp_options_received tmp_opt;
@@ -766,7 +765,7 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
 	if (child == NULL)
 		goto listen_overflow;
 
-	inet_csk_reqsk_queue_unlink(sk, req, prev);
+	inet_csk_reqsk_queue_unlink(sk, req);
 	inet_csk_reqsk_queue_removed(sk, req);
 
 	inet_csk_reqsk_queue_add(sk, req, child);
@@ -791,7 +790,7 @@ embryonic_reset:
 		tcp_reset(sk);
 	}
 	if (!fastopen) {
-		inet_csk_reqsk_queue_drop(sk, req, prev);
+		inet_csk_reqsk_queue_drop(sk, req);
 		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_EMBRYONICRSTS);
 	}
 	return NULL;