Augment struct tcpstat with tcps_states[], which is used for book-keeping

the amount of TCP connections by state.  Provides a cheap way to get
connection count without traversing the whole pcb list.

Sponsored by:	Netflix

8 files changed, 24 insertions, 4 deletions

diff --git a/sys/dev/cxgbe/tom/t4_cpl_io.c b/sys/dev/cxgbe/tom/t4_cpl_io.c
index f18f115..43e4d611 100644
--- a/sys/dev/cxgbe/tom/t4_cpl_io.c
+++ b/sys/dev/cxgbe/tom/t4_cpl_io.c
@@ -45,10 +45,10 @@ __FBSDID("$FreeBSD$");
 #include <netinet/in_pcb.h>
 #include <netinet/ip.h>
 #include <netinet/ip6.h>
-#include <netinet/tcp_var.h>
 #define TCPSTATES
 #include <netinet/tcp_fsm.h>
 #include <netinet/tcp_seq.h>
+#include <netinet/tcp_var.h>
 #include <netinet/toecore.h>
 
 #include "common/common.h"
diff --git a/sys/netinet/tcp_offload.c b/sys/netinet/tcp_offload.c
index 683e212..60fd7e9 100644
--- a/sys/netinet/tcp_offload.c
+++ b/sys/netinet/tcp_offload.c
@@ -42,10 +42,10 @@ __FBSDID("$FreeBSD$");
 #include <netinet/in.h>
 #include <netinet/in_pcb.h>
 #include <netinet/tcp.h>
-#include <netinet/tcp_var.h>
 #include <netinet/tcp_offload.h>
 #define	TCPOUTFLAGS
 #include <netinet/tcp_fsm.h>
+#include <netinet/tcp_var.h>
 #include <netinet/toecore.h>
 
 int registered_toedevs;
diff --git a/sys/netinet/tcp_subr.c b/sys/netinet/tcp_subr.c
index 6358e81..b16f540 100644
--- a/sys/netinet/tcp_subr.c
+++ b/sys/netinet/tcp_subr.c
@@ -1468,6 +1468,7 @@ tcp_close(struct tcpcb *tp)
 #endif
 	in_pcbdrop(inp);
 	TCPSTAT_INC(tcps_closed);
+	TCPSTAT_DEC(tcps_states[tp->t_state]);
 	KASSERT(inp->inp_socket != NULL, ("tcp_close: inp_socket NULL"));
 	so = inp->inp_socket;
 	soisdisconnected(so);
@@ -2910,6 +2911,8 @@ tcp_state_change(struct tcpcb *tp, int newstate)
 	int pstate = tp->t_state;
 #endif
 
+	TCPSTAT_DEC(tcps_states[tp->t_state]);
+	TCPSTAT_INC(tcps_states[newstate]);
 	tp->t_state = newstate;
 	TCP_PROBE6(state__change, NULL, tp, NULL, tp, NULL, pstate);
 }
diff --git a/sys/netinet/tcp_syncache.c b/sys/netinet/tcp_syncache.c
index 940d3de..45e00e9 100644
--- a/sys/netinet/tcp_syncache.c
+++ b/sys/netinet/tcp_syncache.c
@@ -351,6 +351,7 @@ syncache_insert(struct syncache *sc, struct syncache_head *sch)
 
 	SCH_UNLOCK(sch);
 
+	TCPSTAT_INC(tcps_states[TCPS_SYN_RECEIVED]);
 	TCPSTAT_INC(tcps_sc_added);
 }
 
@@ -364,6 +365,7 @@ syncache_drop(struct syncache *sc, struct syncache_head *sch)
 
 	SCH_LOCK_ASSERT(sch);
 
+	TCPSTAT_DEC(tcps_states[TCPS_SYN_RECEIVED]);
 	TAILQ_REMOVE(&sch->sch_bucket, sc, sc_hash);
 	sch->sch_length--;
 
@@ -992,7 +994,16 @@ syncache_expand(struct in_conninfo *inc, struct tcpopt *to, struct tcphdr *th,
 			goto failed;
 		}
 	} else {
-		/* Pull out the entry to unlock the bucket row. */
+		/*
+		 * Pull out the entry to unlock the bucket row.
+		 * 
+		 * NOTE: We must decrease TCPS_SYN_RECEIVED count here, not
+		 * tcp_state_change().  The tcpcb is not existent at this
+		 * moment.  A new one will be allocated via syncache_socket->
+		 * sonewconn->tcp_usr_attach in TCPS_CLOSED state, then
+		 * syncache_socket() will change it to TCPS_SYN_RECEIVED.
+		 */
+		TCPSTAT_DEC(tcps_states[TCPS_SYN_RECEIVED]);
 		TAILQ_REMOVE(&sch->sch_bucket, sc, sc_hash);
 		sch->sch_length--;
 #ifdef TCP_OFFLOAD
diff --git a/sys/netinet/tcp_timewait.c b/sys/netinet/tcp_timewait.c
index 4685fe7..c98de24 100644
--- a/sys/netinet/tcp_timewait.c
+++ b/sys/netinet/tcp_timewait.c
@@ -660,6 +660,7 @@ tcp_tw_2msl_stop(struct tcptw *tw, int reuse)
 
 	if (!reuse)
 		uma_zfree(V_tcptw_zone, tw);
+	TCPSTAT_DEC(tcps_states[TCPS_TIME_WAIT]);
 }
 
 struct tcptw *
diff --git a/sys/netinet/tcp_usrreq.c b/sys/netinet/tcp_usrreq.c
index 4b3150b..0a87a62 100644
--- a/sys/netinet/tcp_usrreq.c
+++ b/sys/netinet/tcp_usrreq.c
@@ -1883,6 +1883,7 @@ tcp_attach(struct socket *so)
 	tp->t_state = TCPS_CLOSED;
 	INP_WUNLOCK(inp);
 	INP_INFO_RUNLOCK(&V_tcbinfo);
+	TCPSTAT_INC(tcps_states[TCPS_CLOSED]);
 	return (0);
 }
 
diff --git a/sys/netinet/tcp_var.h b/sys/netinet/tcp_var.h
index 4712c6b..32aa0bb 100644
--- a/sys/netinet/tcp_var.h
+++ b/sys/netinet/tcp_var.h
@@ -34,6 +34,7 @@
 #define _NETINET_TCP_VAR_H_
 
 #include <netinet/tcp.h>
+#include <netinet/tcp_fsm.h>
 
 #ifdef _KERNEL
 #include <net/vnet.h>
@@ -587,6 +588,9 @@ struct	tcpstat {
 	uint64_t tcps_sig_err_sigopt;	/* No signature expected by socket */
 	uint64_t tcps_sig_err_nosigopt;	/* No signature provided by segment */
 
+	/* Running connection count. */
+	uint64_t tcps_states[TCP_NSTATES];
+
 	uint64_t _pad[12];		/* 6 UTO, 6 TBD */
 };
 
diff --git a/usr.bin/systat/netstat.c b/usr.bin/systat/netstat.c
index 3f994e8..56bc34e 100644
--- a/usr.bin/systat/netstat.c
+++ b/usr.bin/systat/netstat.c
@@ -59,10 +59,10 @@ static const char sccsid[] = "@(#)netstat.c	8.1 (Berkeley) 6/6/93";
 #include <netinet/tcp.h>
 #include <netinet/tcpip.h>
 #include <netinet/tcp_seq.h>
-#include <netinet/tcp_var.h>
 #define TCPSTATES
 #include <netinet/tcp_fsm.h>
 #include <netinet/tcp_timer.h>
+#include <netinet/tcp_var.h>
 #include <netinet/tcp_debug.h>
 #include <netinet/udp.h>
 #include <netinet/udp_var.h>