Back when we had T/TCP support, we used to apply different

timeouts for TCP and T/TCP connections in the TIME_WAIT
state, and we had two separate timed wait queues for them.
Now that is has gone, the timeout is always 2*MSL again,
and there is no reason to keep two queues (the first was
unused anyway!).

Also, reimplement the remaining queue using a TAILQ (it
was technically impossible before, with two queues).

7 files changed, 30 insertions, 55 deletions

diff --git a/sys/netinet/tcp_input.c b/sys/netinet/tcp_input.c
index 0699193..18b20e7 100644
--- a/sys/netinet/tcp_input.c
+++ b/sys/netinet/tcp_input.c
@@ -3187,7 +3187,7 @@ tcp_timewait(inp, to, th, m, tlen)
 	const int isipv6 = 0;
 #endif
 
-	/* tcbinfo lock required for tcp_twclose(), tcp_2msl_reset. */
+	/* tcbinfo lock required for tcp_twclose(), tcp_timer_2msl_reset(). */
 	INP_INFO_WLOCK_ASSERT(&tcbinfo);
 	INP_LOCK_ASSERT(inp);
 
@@ -3256,7 +3256,7 @@ tcp_timewait(inp, to, th, m, tlen)
 	if (thflags & TH_FIN) {
 		seq = th->th_seq + tlen + (thflags & TH_SYN ? 1 : 0);
 		if (seq + 1 == tw->rcv_nxt)
-			tcp_timer_2msl_reset(tw, 2 * tcp_msl, 1);
+			tcp_timer_2msl_reset(tw, 1);
 	}
 
 	/*
diff --git a/sys/netinet/tcp_reass.c b/sys/netinet/tcp_reass.c
index 0699193..18b20e7 100644
--- a/sys/netinet/tcp_reass.c
+++ b/sys/netinet/tcp_reass.c
@@ -3187,7 +3187,7 @@ tcp_timewait(inp, to, th, m, tlen)
 	const int isipv6 = 0;
 #endif
 
-	/* tcbinfo lock required for tcp_twclose(), tcp_2msl_reset. */
+	/* tcbinfo lock required for tcp_twclose(), tcp_timer_2msl_reset(). */
 	INP_INFO_WLOCK_ASSERT(&tcbinfo);
 	INP_LOCK_ASSERT(inp);
 
@@ -3256,7 +3256,7 @@ tcp_timewait(inp, to, th, m, tlen)
 	if (thflags & TH_FIN) {
 		seq = th->th_seq + tlen + (thflags & TH_SYN ? 1 : 0);
 		if (seq + 1 == tw->rcv_nxt)
-			tcp_timer_2msl_reset(tw, 2 * tcp_msl, 1);
+			tcp_timer_2msl_reset(tw, 1);
 	}
 
 	/*
diff --git a/sys/netinet/tcp_subr.c b/sys/netinet/tcp_subr.c
index 39acf62..85d5a9e 100644
--- a/sys/netinet/tcp_subr.c
+++ b/sys/netinet/tcp_subr.c
@@ -1736,7 +1736,7 @@ tcp_twstart(struct tcpcb *tp)
 {
 	struct tcptw *tw;
 	struct inpcb *inp;
-	int tw_time, acknow;
+	int acknow;
 	struct socket *so;
 
 	INP_INFO_WLOCK_ASSERT(&tcbinfo);	/* tcp_timer_2msl_reset(). */
@@ -1781,7 +1781,6 @@ tcp_twstart(struct tcpcb *tp)
  * be used for fin-wait-2 state also, then we may need
  * a ts_recent from the last segment.
  */
-	tw_time = 2 * tcp_msl;
 	acknow = tp->t_flags & TF_ACKNOW;
 
 	/*
@@ -1803,7 +1802,7 @@ tcp_twstart(struct tcpcb *tp)
 		tcp_twrespond(tw, TH_ACK);
 	inp->inp_ppcb = tw;
 	inp->inp_vflag |= INP_TIMEWAIT;
-	tcp_timer_2msl_reset(tw, tw_time, 0);
+	tcp_timer_2msl_reset(tw, 0);
 
 	/*
 	 * If the inpcb owns the sole reference to the socket, then we can
diff --git a/sys/netinet/tcp_timer.c b/sys/netinet/tcp_timer.c
index a5db5a0..86d9c6a 100644
--- a/sys/netinet/tcp_timer.c
+++ b/sys/netinet/tcp_timer.c
@@ -230,45 +230,30 @@ tcp_timer_2msl(xtp)
 }
 
 /*
- * The timed wait lists contain references to each of the TCP sessions
- * currently TIME_WAIT state.  The list pointers, including the list pointers
- * in each tcptw structure, are protected using the global tcbinfo lock,
- * which must be held over list iteration and modification.
+ * The timed wait queue contains references to each of the TCP sessions
+ * currently in the TIME_WAIT state.  The queue pointers, including the
+ * queue pointers in each tcptw structure, are protected using the global
+ * tcbinfo lock, which must be held over queue iteration and modification.
  */
-struct twlist {
-	LIST_HEAD(, tcptw)	tw_list;
-	struct tcptw	tw_tail;
-};
-#define TWLIST_NLISTS	2
-static struct twlist twl_2msl[TWLIST_NLISTS];
+static TAILQ_HEAD(, tcptw)	twq_2msl;
 
 void
 tcp_timer_init(void)
 {
-	int i;
-	struct twlist *twl;
 
-	for (i = 0; i < TWLIST_NLISTS; i++) {
-		twl = &twl_2msl[i];
-		LIST_INIT(&twl->tw_list);
-		LIST_INSERT_HEAD(&twl->tw_list, &twl->tw_tail, tw_2msl);
-	}
+	TAILQ_INIT(&twq_2msl);
 }
 
 void
-tcp_timer_2msl_reset(struct tcptw *tw, int timeo, int rearm)
+tcp_timer_2msl_reset(struct tcptw *tw, int rearm)
 {
-	int i;
-	struct tcptw *tw_tail;
 
 	INP_INFO_WLOCK_ASSERT(&tcbinfo);
 	INP_LOCK_ASSERT(tw->tw_inpcb);
 	if (rearm)
-		LIST_REMOVE(tw, tw_2msl);
-	tw->tw_time = timeo + ticks;
-	i = timeo > tcp_msl ? 1 : 0;
-	tw_tail = &twl_2msl[i].tw_tail;
-	LIST_INSERT_BEFORE(tw_tail, tw, tw_2msl);
+		TAILQ_REMOVE(&twq_2msl, tw, tw_2msl);
+	tw->tw_time = ticks + 2 * tcp_msl;
+	TAILQ_INSERT_TAIL(&twq_2msl, tw, tw_2msl);
 }
 
 void
@@ -276,31 +261,23 @@ tcp_timer_2msl_stop(struct tcptw *tw)
 {
 
 	INP_INFO_WLOCK_ASSERT(&tcbinfo);
-	LIST_REMOVE(tw, tw_2msl);
+	TAILQ_REMOVE(&twq_2msl, tw, tw_2msl);
 }
 
 struct tcptw *
 tcp_timer_2msl_tw(int reuse)
 {
-	struct tcptw *tw, *tw_tail;
-	struct twlist *twl;
-	int i;
+	struct tcptw *tw;
 
 	INP_INFO_WLOCK_ASSERT(&tcbinfo);
-	for (i = 0; i < TWLIST_NLISTS; i++) {
-		twl = &twl_2msl[i];
-		tw_tail = &twl->tw_tail;
-
-		for (;;) {
-			tw = LIST_FIRST(&twl->tw_list);
-			if (tw == tw_tail || (!reuse && tw->tw_time > ticks))
-				break;
-			INP_LOCK(tw->tw_inpcb);
-			tcp_twclose(tw, reuse);
-			if (reuse)
-				return (tw);
-		}
-
+	for (;;) {
+		tw = TAILQ_FIRST(&twq_2msl);
+		if (tw == NULL || (!reuse && tw->tw_time > ticks))
+			break;
+		INP_LOCK(tw->tw_inpcb);
+		tcp_twclose(tw, reuse);
+		if (reuse)
+			return (tw);
 	}
 	return (NULL);
 }
diff --git a/sys/netinet/tcp_timer.h b/sys/netinet/tcp_timer.h
index 815a757..4b32cbb 100644
--- a/sys/netinet/tcp_timer.h
+++ b/sys/netinet/tcp_timer.h
@@ -156,7 +156,7 @@ void	tcp_timer_init(void);
 void	tcp_timer_2msl(void *xtp);
 struct tcptw *
 	tcp_timer_2msl_tw(int _reuse);		/* XXX temporary */
-void	tcp_timer_2msl_reset(struct tcptw *_tw, int _timeo, int rearm);
+void	tcp_timer_2msl_reset(struct tcptw *_tw, int rearm);
 void	tcp_timer_2msl_stop(struct tcptw *_tw);
 void	tcp_timer_keep(void *xtp);
 void	tcp_timer_persist(void *xtp);
diff --git a/sys/netinet/tcp_timewait.c b/sys/netinet/tcp_timewait.c
index 39acf62..85d5a9e 100644
--- a/sys/netinet/tcp_timewait.c
+++ b/sys/netinet/tcp_timewait.c
@@ -1736,7 +1736,7 @@ tcp_twstart(struct tcpcb *tp)
 {
 	struct tcptw *tw;
 	struct inpcb *inp;
-	int tw_time, acknow;
+	int acknow;
 	struct socket *so;
 
 	INP_INFO_WLOCK_ASSERT(&tcbinfo);	/* tcp_timer_2msl_reset(). */
@@ -1781,7 +1781,6 @@ tcp_twstart(struct tcpcb *tp)
  * be used for fin-wait-2 state also, then we may need
  * a ts_recent from the last segment.
  */
-	tw_time = 2 * tcp_msl;
 	acknow = tp->t_flags & TF_ACKNOW;
 
 	/*
@@ -1803,7 +1802,7 @@ tcp_twstart(struct tcpcb *tp)
 		tcp_twrespond(tw, TH_ACK);
 	inp->inp_ppcb = tw;
 	inp->inp_vflag |= INP_TIMEWAIT;
-	tcp_timer_2msl_reset(tw, tw_time, 0);
+	tcp_timer_2msl_reset(tw, 0);
 
 	/*
 	 * If the inpcb owns the sole reference to the socket, then we can
diff --git a/sys/netinet/tcp_var.h b/sys/netinet/tcp_var.h
index 4aa5cda..7658485 100644
--- a/sys/netinet/tcp_var.h
+++ b/sys/netinet/tcp_var.h
@@ -276,7 +276,7 @@ struct tcptw {
 	u_long		t_recent;
 	u_long		t_starttime;
 	int		tw_time;
-	LIST_ENTRY(tcptw) tw_2msl;
+	TAILQ_ENTRY(tcptw) tw_2msl;
 };
 
 #define	intotcpcb(ip)	((struct tcpcb *)(ip)->inp_ppcb)