From 9c3507f91987b7c8ce3b895a5ee46a1de6bc42f2 Mon Sep 17 00:00:00 2001
From: Gleb Smirnoff <glebius@FreeBSD.org>
Date: Thu, 6 Oct 2022 19:22:23 -0700
Subject: tcp: in tcp_usr_detach() remove special handling of compressed
 time-wait

Differential revision:	https://reviews.freebsd.org/D36399
---
 sys/netinet/tcp_usrreq.c | 59 ++++++------------------------------------------
 1 file changed, 7 insertions(+), 52 deletions(-)

diff --git a/sys/netinet/tcp_usrreq.c b/sys/netinet/tcp_usrreq.c
index 2c8b04aa2953..43acc0ad1719 100644
--- a/sys/netinet/tcp_usrreq.c
+++ b/sys/netinet/tcp_usrreq.c
@@ -216,58 +216,13 @@ tcp_usr_detach(struct socket *so)
 
 	tp = intotcpcb(inp);
 
-	if (inp->inp_flags & INP_TIMEWAIT) {
-		/*
-		 * There are two cases to handle: one in which the time wait
-		 * state is being discarded (INP_DROPPED), and one in which
-		 * this connection will remain in timewait.  In the former,
-		 * it is time to discard all state (except tcptw, which has
-		 * already been discarded by the timewait close code, which
-		 * should be further up the call stack somewhere).  In the
-		 * latter case, we detach from the socket, but leave the pcb
-		 * present until timewait ends.
-		 *
-		 * XXXRW: Would it be cleaner to free the tcptw here?
-		 *
-		 * Astute question indeed, from twtcp perspective there are
-		 * four cases to consider:
-		 *
-		 * #1 tcp_usr_detach is called at tcptw creation time by
-		 *  tcp_twstart, then do not discard the newly created tcptw
-		 *  and leave inpcb present until timewait ends
-		 * #2 tcp_usr_detach is called at tcptw creation time by
-		 *  tcp_twstart, but connection is local and tw will be
-		 *  discarded immediately
-		 * #3 tcp_usr_detach is called at timewait end (or reuse) by
-		 *  tcp_twclose, then the tcptw has already been discarded
-		 *  (or reused) and inpcb is freed here
-		 * #4 tcp_usr_detach is called() after timewait ends (or reuse)
-		 *  (e.g. by soclose), then tcptw has already been discarded
-		 *  (or reused) and inpcb is freed here
-		 *
-		 *  In all three cases the tcptw should not be freed here.
-		 */
-		if (inp->inp_flags & INP_DROPPED) {
-			KASSERT(tp == NULL, ("tcp_detach: INP_TIMEWAIT && "
-			    "INP_DROPPED && tp != NULL"));
-			in_pcbdetach(inp);
-			in_pcbfree(inp);
-		} else {
-			in_pcbdetach(inp);
-			INP_WUNLOCK(inp);
-		}
-	} else {
-		/*
-		 * If the connection is not in timewait, it must be either
-		 * dropped or embryonic.
-		 */
-		KASSERT(inp->inp_flags & INP_DROPPED ||
-		    tp->t_state < TCPS_SYN_SENT,
-		    ("%s: inp %p not dropped or embryonic", __func__, inp));
-		tcp_discardcb(tp);
-		in_pcbdetach(inp);
-		in_pcbfree(inp);
-	}
+	KASSERT(inp->inp_flags & INP_DROPPED ||
+	    tp->t_state < TCPS_SYN_SENT,
+	    ("%s: inp %p not dropped or embryonic", __func__, inp));
+
+	tcp_discardcb(tp);
+	in_pcbdetach(inp);
+	in_pcbfree(inp);
 }
 
 #ifdef INET
-- 
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