---

yaml
---
r: 315513
b: refs/heads/master
c: 783237e
h: refs/heads/master
i:
  315511: 59c688a
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 1fe4c481ba637660793217769695c146a037bd54
+refs/heads/master: 783237e8daf13481ee234997cbbbb823872ac388

trunk/include/linux/snmp.h

@@ -238,6 +238,7 @@ enum
 	LINUX_MIB_TCPOFOMERGE,			/* TCPOFOMerge */
 	LINUX_MIB_TCPCHALLENGEACK,		/* TCPChallengeACK */
 	LINUX_MIB_TCPSYNCHALLENGE,		/* TCPSYNChallenge */
+	LINUX_MIB_TCPFASTOPENACTIVE,		/* TCPFastOpenActive */
 	__LINUX_MIB_MAX
 };
 

trunk/include/linux/tcp.h

@@ -386,7 +386,8 @@ struct tcp_sock {
 		unused      : 1;
 	u8	repair_queue;
 	u8	do_early_retrans:1,/* Enable RFC5827 early-retransmit  */
-		early_retrans_delayed:1; /* Delayed ER timer installed */
+		early_retrans_delayed:1, /* Delayed ER timer installed */
+		syn_fastopen:1;	/* SYN includes Fast Open option */
 
 /* RTT measurement */
 	u32	srtt;		/* smoothed round trip time << 3	*/
@@ -500,6 +501,9 @@ struct tcp_sock {
 	struct tcp_md5sig_info	__rcu *md5sig_info;
 #endif
 
+/* TCP fastopen related information */
+	struct tcp_fastopen_request *fastopen_req;
+
 	/* When the cookie options are generated and exchanged, then this
 	 * object holds a reference to them (cookie_values->kref).  Also
 	 * contains related tcp_cookie_transactions fields.

trunk/include/net/tcp.h

@@ -1289,6 +1289,15 @@ extern int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff
 extern int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
 			    const struct tcp_md5sig_key *key);
 
+struct tcp_fastopen_request {
+	/* Fast Open cookie. Size 0 means a cookie request */
+	struct tcp_fastopen_cookie	cookie;
+	struct msghdr			*data;  /* data in MSG_FASTOPEN */
+	u16				copied;	/* queued in tcp_connect() */
+};
+
+void tcp_free_fastopen_req(struct tcp_sock *tp);
+
 /* write queue abstraction */
 static inline void tcp_write_queue_purge(struct sock *sk)
 {

trunk/net/ipv4/af_inet.c

@@ -556,11 +556,12 @@ int inet_dgram_connect(struct socket *sock, struct sockaddr *uaddr,
 }
 EXPORT_SYMBOL(inet_dgram_connect);
 
-static long inet_wait_for_connect(struct sock *sk, long timeo)
+static long inet_wait_for_connect(struct sock *sk, long timeo, int writebias)
 {
 	DEFINE_WAIT(wait);
 
 	prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
+	sk->sk_write_pending += writebias;
 
 	/* Basic assumption: if someone sets sk->sk_err, he _must_
 	 * change state of the socket from TCP_SYN_*.
@@ -576,6 +577,7 @@ static long inet_wait_for_connect(struct sock *sk, long timeo)
 		prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
 	}
 	finish_wait(sk_sleep(sk), &wait);
+	sk->sk_write_pending -= writebias;
 	return timeo;
 }
 
@@ -634,8 +636,12 @@ int inet_stream_connect(struct socket *sock, struct sockaddr *uaddr,
 	timeo = sock_sndtimeo(sk, flags & O_NONBLOCK);
 
 	if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
+		int writebias = (sk->sk_protocol == IPPROTO_TCP) &&
+				tcp_sk(sk)->fastopen_req &&
+				tcp_sk(sk)->fastopen_req->data ? 1 : 0;
+
 		/* Error code is set above */
-		if (!timeo || !inet_wait_for_connect(sk, timeo))
+		if (!timeo || !inet_wait_for_connect(sk, timeo, writebias))
 			goto out;
 
 		err = sock_intr_errno(timeo);

trunk/net/ipv4/proc.c

@@ -262,6 +262,7 @@ static const struct snmp_mib snmp4_net_list[] = {
 	SNMP_MIB_ITEM("TCPOFOMerge", LINUX_MIB_TCPOFOMERGE),
 	SNMP_MIB_ITEM("TCPChallengeACK", LINUX_MIB_TCPCHALLENGEACK),
 	SNMP_MIB_ITEM("TCPSYNChallenge", LINUX_MIB_TCPSYNCHALLENGE),
+	SNMP_MIB_ITEM("TCPFastOpenActive", LINUX_MIB_TCPFASTOPENACTIVE),
 	SNMP_MIB_SENTINEL
 };
 

trunk/net/ipv4/tcp_output.c

@@ -596,6 +596,7 @@ static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb,
 	u8 cookie_size = (!tp->rx_opt.cookie_out_never && cvp != NULL) ?
 			 tcp_cookie_size_check(cvp->cookie_desired) :
 			 0;
+	struct tcp_fastopen_request *fastopen = tp->fastopen_req;
 
 #ifdef CONFIG_TCP_MD5SIG
 	*md5 = tp->af_specific->md5_lookup(sk, sk);
@@ -636,6 +637,16 @@ static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb,
 			remaining -= TCPOLEN_SACKPERM_ALIGNED;
 	}
 
+	if (fastopen && fastopen->cookie.len >= 0) {
+		u32 need = TCPOLEN_EXP_FASTOPEN_BASE + fastopen->cookie.len;
+		need = (need + 3) & ~3U;  /* Align to 32 bits */
+		if (remaining >= need) {
+			opts->options |= OPTION_FAST_OPEN_COOKIE;
+			opts->fastopen_cookie = &fastopen->cookie;
+			remaining -= need;
+			tp->syn_fastopen = 1;
+		}
+	}
 	/* Note that timestamps are required by the specification.
 	 *
 	 * Odd numbers of bytes are prohibited by the specification, ensuring
@@ -2824,6 +2835,96 @@ void tcp_connect_init(struct sock *sk)
 	tcp_clear_retrans(tp);
 }
 
+static void tcp_connect_queue_skb(struct sock *sk, struct sk_buff *skb)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
+
+	tcb->end_seq += skb->len;
+	skb_header_release(skb);
+	__tcp_add_write_queue_tail(sk, skb);
+	sk->sk_wmem_queued += skb->truesize;
+	sk_mem_charge(sk, skb->truesize);
+	tp->write_seq = tcb->end_seq;
+	tp->packets_out += tcp_skb_pcount(skb);
+}
+
+/* Build and send a SYN with data and (cached) Fast Open cookie. However,
+ * queue a data-only packet after the regular SYN, such that regular SYNs
+ * are retransmitted on timeouts. Also if the remote SYN-ACK acknowledges
+ * only the SYN sequence, the data are retransmitted in the first ACK.
+ * If cookie is not cached or other error occurs, falls back to send a
+ * regular SYN with Fast Open cookie request option.
+ */
+static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct tcp_fastopen_request *fo = tp->fastopen_req;
+	int space, i, err = 0, iovlen = fo->data->msg_iovlen;
+	struct sk_buff *syn_data = NULL, *data;
+
+	tcp_fastopen_cache_get(sk, &tp->rx_opt.mss_clamp, &fo->cookie);
+	if (fo->cookie.len <= 0)
+		goto fallback;
+
+	/* MSS for SYN-data is based on cached MSS and bounded by PMTU and
+	 * user-MSS. Reserve maximum option space for middleboxes that add
+	 * private TCP options. The cost is reduced data space in SYN :(
+	 */
+	if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < tp->rx_opt.mss_clamp)
+		tp->rx_opt.mss_clamp = tp->rx_opt.user_mss;
+	space = tcp_mtu_to_mss(sk, inet_csk(sk)->icsk_pmtu_cookie) -
+		MAX_TCP_OPTION_SPACE;
+
+	syn_data = skb_copy_expand(syn, skb_headroom(syn), space,
+				   sk->sk_allocation);
+	if (syn_data == NULL)
+		goto fallback;
+
+	for (i = 0; i < iovlen && syn_data->len < space; ++i) {
+		struct iovec *iov = &fo->data->msg_iov[i];
+		unsigned char __user *from = iov->iov_base;
+		int len = iov->iov_len;
+
+		if (syn_data->len + len > space)
+			len = space - syn_data->len;
+		else if (i + 1 == iovlen)
+			/* No more data pending in inet_wait_for_connect() */
+			fo->data = NULL;
+
+		if (skb_add_data(syn_data, from, len))
+			goto fallback;
+	}
+
+	/* Queue a data-only packet after the regular SYN for retransmission */
+	data = pskb_copy(syn_data, sk->sk_allocation);
+	if (data == NULL)
+		goto fallback;
+	TCP_SKB_CB(data)->seq++;
+	TCP_SKB_CB(data)->tcp_flags &= ~TCPHDR_SYN;
+	TCP_SKB_CB(data)->tcp_flags = (TCPHDR_ACK|TCPHDR_PSH);
+	tcp_connect_queue_skb(sk, data);
+	fo->copied = data->len;
+
+	if (tcp_transmit_skb(sk, syn_data, 0, sk->sk_allocation) == 0) {
+		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPFASTOPENACTIVE);
+		goto done;
+	}
+	syn_data = NULL;
+
+fallback:
+	/* Send a regular SYN with Fast Open cookie request option */
+	if (fo->cookie.len > 0)
+		fo->cookie.len = 0;
+	err = tcp_transmit_skb(sk, syn, 1, sk->sk_allocation);
+	if (err)
+		tp->syn_fastopen = 0;
+	kfree_skb(syn_data);
+done:
+	fo->cookie.len = -1;  /* Exclude Fast Open option for SYN retries */
+	return err;
+}
+
 /* Build a SYN and send it off. */
 int tcp_connect(struct sock *sk)
 {
@@ -2841,17 +2942,13 @@ int tcp_connect(struct sock *sk)
 	skb_reserve(buff, MAX_TCP_HEADER);
 
 	tcp_init_nondata_skb(buff, tp->write_seq++, TCPHDR_SYN);
+	tp->retrans_stamp = TCP_SKB_CB(buff)->when = tcp_time_stamp;
+	tcp_connect_queue_skb(sk, buff);
 	TCP_ECN_send_syn(sk, buff);
 
-	/* Send it off. */
-	TCP_SKB_CB(buff)->when = tcp_time_stamp;
-	tp->retrans_stamp = TCP_SKB_CB(buff)->when;
-	skb_header_release(buff);
-	__tcp_add_write_queue_tail(sk, buff);
-	sk->sk_wmem_queued += buff->truesize;
-	sk_mem_charge(sk, buff->truesize);
-	tp->packets_out += tcp_skb_pcount(buff);
-	err = tcp_transmit_skb(sk, buff, 1, sk->sk_allocation);
+	/* Send off SYN; include data in Fast Open. */
+	err = tp->fastopen_req ? tcp_send_syn_data(sk, buff) :
+	      tcp_transmit_skb(sk, buff, 1, sk->sk_allocation);
 	if (err == -ECONNREFUSED)
 		return err;