diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index a48d00318683cc726c101ee3a7dd101fbd3bd912..0caa3a2d4106eab0137d20ac75518af7964281ba 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -189,6 +189,7 @@ struct tcp_sock {
 	u8	do_early_retrans:1,/* Enable RFC5827 early-retransmit  */
 		syn_data:1,	/* SYN includes data */
 		syn_fastopen:1,	/* SYN includes Fast Open option */
+		syn_fastopen_exp:1,/* SYN includes Fast Open exp. option */
 		syn_data_acked:1,/* data in SYN is acked by SYN-ACK */
 		is_cwnd_limited:1;/* forward progress limited by snd_cwnd? */
 	u32	tlp_high_seq;	/* snd_nxt at the time of TLP retransmit. */
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 7292c3c575bc9eddf2736199776fa6df0c406ab5..9598871485ce3d7d36f96be9643d94e7ca85cfe0 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1339,7 +1339,8 @@ void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
 			    struct tcp_fastopen_cookie *cookie, int *syn_loss,
 			    unsigned long *last_syn_loss);
 void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
-			    struct tcp_fastopen_cookie *cookie, bool syn_lost);
+			    struct tcp_fastopen_cookie *cookie, bool syn_lost,
+			    u16 try_exp);
 struct tcp_fastopen_request {
 	/* Fast Open cookie. Size 0 means a cookie request */
 	struct tcp_fastopen_cookie	cookie;
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 24f1630b2afb2c7b9a6d32efb9536845dda7176b..031cf72cd05c8094de8a9a76cd4cffa13e45c0d5 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -5378,8 +5378,8 @@ static bool tcp_rcv_fastopen_synack(struct sock *sk, struct sk_buff *synack,
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 	struct sk_buff *data = tp->syn_data ? tcp_write_queue_head(sk) : NULL;
-	u16 mss = tp->rx_opt.mss_clamp;
-	bool syn_drop;
+	u16 mss = tp->rx_opt.mss_clamp, try_exp = 0;
+	bool syn_drop = false;
 
 	if (mss == tp->rx_opt.user_mss) {
 		struct tcp_options_received opt;
@@ -5391,16 +5391,25 @@ static bool tcp_rcv_fastopen_synack(struct sock *sk, struct sk_buff *synack,
 		mss = opt.mss_clamp;
 	}
 
-	if (!tp->syn_fastopen)  /* Ignore an unsolicited cookie */
+	if (!tp->syn_fastopen) {
+		/* Ignore an unsolicited cookie */
 		cookie->len = -1;
+	} else if (tp->total_retrans) {
+		/* SYN timed out and the SYN-ACK neither has a cookie nor
+		 * acknowledges data. Presumably the remote received only
+		 * the retransmitted (regular) SYNs: either the original
+		 * SYN-data or the corresponding SYN-ACK was dropped.
+		 */
+		syn_drop = (cookie->len < 0 && data);
+	} else if (cookie->len < 0 && !tp->syn_data) {
+		/* We requested a cookie but didn't get it. If we did not use
+		 * the (old) exp opt format then try so next time (try_exp=1).
+		 * Otherwise we go back to use the RFC7413 opt (try_exp=2).
+		 */
+		try_exp = tp->syn_fastopen_exp ? 2 : 1;
+	}
 
-	/* The SYN-ACK neither has cookie nor acknowledges the data. Presumably
-	 * the remote receives only the retransmitted (regular) SYNs: either
-	 * the original SYN-data or the corresponding SYN-ACK is lost.
-	 */
-	syn_drop = (cookie->len <= 0 && data && tp->total_retrans);
-
-	tcp_fastopen_cache_set(sk, mss, cookie, syn_drop);
+	tcp_fastopen_cache_set(sk, mss, cookie, syn_drop, try_exp);
 
 	if (data) { /* Retransmit unacked data in SYN */
 		tcp_for_write_queue_from(data, sk) {
diff --git a/net/ipv4/tcp_metrics.c b/net/ipv4/tcp_metrics.c
index 78ecc4a017128adf389c33418c937134f111e39d..a51d63a43e33af5fc751e4f0f3369b9394776975 100644
--- a/net/ipv4/tcp_metrics.c
+++ b/net/ipv4/tcp_metrics.c
@@ -28,7 +28,8 @@ static struct tcp_metrics_block *__tcp_get_metrics(const struct inetpeer_addr *s
 
 struct tcp_fastopen_metrics {
 	u16	mss;
-	u16	syn_loss:10;		/* Recurring Fast Open SYN losses */
+	u16	syn_loss:10,		/* Recurring Fast Open SYN losses */
+		try_exp:2;		/* Request w/ exp. option (once) */
 	unsigned long	last_syn_loss;	/* Last Fast Open SYN loss */
 	struct	tcp_fastopen_cookie	cookie;
 };
@@ -131,6 +132,8 @@ static void tcpm_suck_dst(struct tcp_metrics_block *tm,
 	if (fastopen_clear) {
 		tm->tcpm_fastopen.mss = 0;
 		tm->tcpm_fastopen.syn_loss = 0;
+		tm->tcpm_fastopen.try_exp = 0;
+		tm->tcpm_fastopen.cookie.exp = false;
 		tm->tcpm_fastopen.cookie.len = 0;
 	}
 }
@@ -713,6 +716,8 @@ void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
 			if (tfom->mss)
 				*mss = tfom->mss;
 			*cookie = tfom->cookie;
+			if (cookie->len <= 0 && tfom->try_exp == 1)
+				cookie->exp = true;
 			*syn_loss = tfom->syn_loss;
 			*last_syn_loss = *syn_loss ? tfom->last_syn_loss : 0;
 		} while (read_seqretry(&fastopen_seqlock, seq));
@@ -721,7 +726,8 @@ void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
 }
 
 void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
-			    struct tcp_fastopen_cookie *cookie, bool syn_lost)
+			    struct tcp_fastopen_cookie *cookie, bool syn_lost,
+			    u16 try_exp)
 {
 	struct dst_entry *dst = __sk_dst_get(sk);
 	struct tcp_metrics_block *tm;
@@ -738,6 +744,9 @@ void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
 			tfom->mss = mss;
 		if (cookie && cookie->len > 0)
 			tfom->cookie = *cookie;
+		else if (try_exp > tfom->try_exp &&
+			 tfom->cookie.len <= 0 && !tfom->cookie.exp)
+			tfom->try_exp = try_exp;
 		if (syn_lost) {
 			++tfom->syn_loss;
 			tfom->last_syn_loss = jiffies;
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 464bd8c5de69682ad9c9c901d7dc98c6b2b6fa4f..e662d85d1635d0269b669bb0f726760be3bae0d2 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -592,13 +592,17 @@ static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb,
 	}
 
 	if (fastopen && fastopen->cookie.len >= 0) {
-		u32 need = TCPOLEN_EXP_FASTOPEN_BASE + fastopen->cookie.len;
+		u32 need = fastopen->cookie.len;
+
+		need += fastopen->cookie.exp ? TCPOLEN_EXP_FASTOPEN_BASE :
+					       TCPOLEN_FASTOPEN_BASE;
 		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;
+			tp->syn_fastopen_exp = fastopen->cookie.exp ? 1 : 0;
 		}
 	}
 
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index 2568fd282873b7436ca2299e20c283e1affd8688..8c65dc147d8bcfb58e14c20b774711ffbcc30d5a 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -167,7 +167,7 @@ static int tcp_write_timeout(struct sock *sk)
 		if (icsk->icsk_retransmits) {
 			dst_negative_advice(sk);
 			if (tp->syn_fastopen || tp->syn_data)
-				tcp_fastopen_cache_set(sk, 0, NULL, true);
+				tcp_fastopen_cache_set(sk, 0, NULL, true, 0);
 			if (tp->syn_data)
 				NET_INC_STATS_BH(sock_net(sk),
 						 LINUX_MIB_TCPFASTOPENACTIVEFAIL);