Merge branch 'tcp-smc-rendezvous'

Ursula Braun says:

====================
TCP experimental option for SMC rendezvous

SMC-capability is to be negotiated with a TCP experimental option.
As requested during code review of our previous approach using
netfilter hooks, here's a new version. It touches tcp-code in the
first patch and exploits the new tcp flag in the smc-code.

Changelog:

V3:
* move include for linux/unaligned/access_ok.h to tcp_input.c

V2:
* switch to current jump labels API
* remove static key checking in smc_set_capability()
  (comment from Eric Dumazet)
* use inet_request_sock parameter for smc_set_option_cond()
* smc_listen_work(): replace local variable lgr_lock_taken by new labels
                     and separate this change into a prerequisite first
                     patch
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 16 insertions, 3 deletions

diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 173a7c2f9636..8c431385b272 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -98,7 +98,8 @@ struct tcp_options_received {
 		tstamp_ok : 1,	/* TIMESTAMP seen on SYN packet		*/
 		dsack : 1,	/* D-SACK is scheduled			*/
 		wscale_ok : 1,	/* Wscale seen on SYN packet		*/
-		sack_ok : 4,	/* SACK seen on SYN packet		*/
+		sack_ok : 3,	/* SACK seen on SYN packet		*/
+		smc_ok : 1,	/* SMC seen on SYN packet		*/
 		snd_wscale : 4,	/* Window scaling received from sender	*/
 		rcv_wscale : 4;	/* Window scaling to send to receiver	*/
 	u8	num_sacks;	/* Number of SACK blocks		*/
@@ -110,6 +111,9 @@ static inline void tcp_clear_options(struct tcp_options_received *rx_opt)
 {
 	rx_opt->tstamp_ok = rx_opt->sack_ok = 0;
 	rx_opt->wscale_ok = rx_opt->snd_wscale = 0;
+#if IS_ENABLED(CONFIG_SMC)
+	rx_opt->smc_ok = 0;
+#endif
 }
 
 /* This is the max number of SACKS that we'll generate and process. It's safe
@@ -229,7 +233,8 @@ struct tcp_sock {
 		syn_fastopen_ch:1, /* Active TFO re-enabling probe */
 		syn_data_acked:1,/* data in SYN is acked by SYN-ACK */
 		save_syn:1,	/* Save headers of SYN packet */
-		is_cwnd_limited:1;/* forward progress limited by snd_cwnd? */
+		is_cwnd_limited:1,/* forward progress limited by snd_cwnd? */
+		syn_smc:1;	/* SYN includes SMC */
 	u32	tlp_high_seq;	/* snd_nxt at the time of TLP retransmit. */
 
 /* RTT measurement */
diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h
index 425752f768d2..c49938d1481a 100644
--- a/include/net/inet_sock.h
+++ b/include/net/inet_sock.h
@@ -92,7 +92,8 @@ struct inet_request_sock {
 				wscale_ok  : 1,
 				ecn_ok	   : 1,
 				acked	   : 1,
-				no_srccheck: 1;
+				no_srccheck: 1,
+				smc_ok	   : 1;
 	kmemcheck_bitfield_end(flags);
 	u32                     ir_mark;
 	union {
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 2392f74074e7..285bc82dea41 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -191,6 +191,7 @@ void tcp_time_wait(struct sock *sk, int state, int timeo);
  * experimental options. See draft-ietf-tcpm-experimental-options-00.txt
  */
 #define TCPOPT_FASTOPEN_MAGIC	0xF989
+#define TCPOPT_SMC_MAGIC	0xE2D4C3D9
 
 /*
  *     TCP option lengths
@@ -203,6 +204,7 @@ void tcp_time_wait(struct sock *sk, int state, int timeo);
 #define TCPOLEN_MD5SIG         18
 #define TCPOLEN_FASTOPEN_BASE  2
 #define TCPOLEN_EXP_FASTOPEN_BASE  4
+#define TCPOLEN_EXP_SMC_BASE   6
 
 /* But this is what stacks really send out. */
 #define TCPOLEN_TSTAMP_ALIGNED		12
@@ -213,6 +215,7 @@ void tcp_time_wait(struct sock *sk, int state, int timeo);
 #define TCPOLEN_SACK_PERBLOCK		8
 #define TCPOLEN_MD5SIG_ALIGNED		20
 #define TCPOLEN_MSS_ALIGNED		4
+#define TCPOLEN_EXP_SMC_BASE_ALIGNED	8
 
 /* Flags in tp->nonagle */
 #define TCP_NAGLE_OFF		1	/* Nagle's algo is disabled */
@@ -2108,4 +2111,8 @@ static inline bool tcp_bpf_ca_needs_ecn(struct sock *sk)
 {
 	return (tcp_call_bpf(sk, BPF_SOCK_OPS_NEEDS_ECN) == 1);
 }
+
+#if IS_ENABLED(CONFIG_SMC)
+extern struct static_key_false tcp_have_smc;
+#endif
 #endif	/* _TCP_H */