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;