Index: head/sys/netinet/tcp_reass.c
===================================================================
--- head/sys/netinet/tcp_reass.c	(revision 339377)
+++ head/sys/netinet/tcp_reass.c	(revision 339378)
@@ -1,1078 +1,1076 @@
 /*-
  * SPDX-License-Identifier: BSD-3-Clause
  *
  * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995
  *	The Regents of the University of California.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  * 3. Neither the name of the University nor the names of its contributors
  *    may be used to endorse or promote products derived from this software
  *    without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
  *	@(#)tcp_input.c	8.12 (Berkeley) 5/24/95
  */
 
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
 #include "opt_inet.h"
 #include "opt_inet6.h"
 #include "opt_tcpdebug.h"
 
 #include <sys/param.h>
 #include <sys/kernel.h>
 #include <sys/eventhandler.h>
 #include <sys/malloc.h>
 #include <sys/mbuf.h>
 #include <sys/socket.h>
 #include <sys/socketvar.h>
 #include <sys/sysctl.h>
 #include <sys/syslog.h>
 #include <sys/systm.h>
 
 #include <vm/uma.h>
 
 #include <net/if.h>
 #include <net/if_var.h>
 #include <net/route.h>
 #include <net/vnet.h>
 
 #include <netinet/in.h>
 #include <netinet/in_pcb.h>
 #include <netinet/in_systm.h>
 #include <netinet/in_var.h>
 #include <netinet/ip.h>
 #include <netinet/ip_var.h>
 #include <netinet/ip_options.h>
 #include <netinet/ip6.h>
 #include <netinet6/in6_pcb.h>
 #include <netinet6/ip6_var.h>
 #include <netinet6/nd6.h>
 #include <netinet/tcp.h>
 #include <netinet/tcp_fsm.h>
 #include <netinet/tcp_seq.h>
 #include <netinet/tcp_timer.h>
 #include <netinet/tcp_var.h>
 #include <netinet/tcp_log_buf.h>
 #include <netinet/tcp_hpts.h>
 #include <netinet6/tcp6_var.h>
 #include <netinet/tcpip.h>
 #ifdef TCPDEBUG
 #include <netinet/tcp_debug.h>
 #endif /* TCPDEBUG */
 
 #define TCP_R_LOG_ADD		1
 #define TCP_R_LOG_LIMIT_REACHED 2
 #define TCP_R_LOG_APPEND	3
 #define TCP_R_LOG_PREPEND	4
 #define TCP_R_LOG_REPLACE	5
 #define TCP_R_LOG_MERGE_INTO	6
 #define TCP_R_LOG_NEW_ENTRY	7
 #define TCP_R_LOG_READ		8
 #define TCP_R_LOG_ZERO		9
 #define TCP_R_LOG_DUMP		10
 #define TCP_R_LOG_TRIM		11
 
 /* For debugging we want counters and BB logging */
 /* #define TCP_REASS_COUNTERS 1 */
 /* #define TCP_REASS_LOGGING 1 */
 
 static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass, CTLFLAG_RW, 0,
     "TCP Segment Reassembly Queue");
 
 static SYSCTL_NODE(_net_inet_tcp_reass, OID_AUTO, stats, CTLFLAG_RW, 0,
     "TCP Segment Reassembly stats");
 
 
 static int tcp_reass_maxseg = 0;
 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RDTUN,
     &tcp_reass_maxseg, 0,
     "Global maximum number of TCP Segments in Reassembly Queue");
 
 static uma_zone_t tcp_reass_zone;
 SYSCTL_UMA_CUR(_net_inet_tcp_reass, OID_AUTO, cursegments, 0,
     &tcp_reass_zone,
     "Global number of TCP Segments currently in Reassembly Queue");
 
 static u_int tcp_reass_maxqueuelen = 100;
 SYSCTL_UINT(_net_inet_tcp_reass, OID_AUTO, maxqueuelen, CTLFLAG_RWTUN,
     &tcp_reass_maxqueuelen, 0,
     "Maximum number of TCP Segments per Reassembly Queue");
 
 static int tcp_new_limits = 0;
 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, new_limit, CTLFLAG_RWTUN,
     &tcp_new_limits, 0,
     "Do we use the new limit method we are discussing?");
 
 static u_int tcp_reass_queue_guard = 16;
 SYSCTL_UINT(_net_inet_tcp_reass, OID_AUTO, queueguard, CTLFLAG_RWTUN,
     &tcp_reass_queue_guard, 16,
     "Number of TCP Segments in Reassembly Queue where we flip over to guard mode");
 
 #ifdef TCP_REASS_COUNTERS
 
 counter_u64_t reass_entry;
 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, entry, CTLFLAG_RD,
     &reass_entry, "A segment entered reassembly ");
 
 counter_u64_t reass_path1;
 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path1, CTLFLAG_RD,
     &reass_path1, "Took path 1");
 
 counter_u64_t reass_path2;
 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path2, CTLFLAG_RD,
     &reass_path2, "Took path 2");
 
 counter_u64_t reass_path3;
 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path3, CTLFLAG_RD,
     &reass_path3, "Took path 3");
 
 counter_u64_t reass_path4;
 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path4, CTLFLAG_RD,
     &reass_path4, "Took path 4");
 
 counter_u64_t reass_path5;
 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path5, CTLFLAG_RD,
     &reass_path5, "Took path 5");
 
 counter_u64_t reass_path6;
 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path6, CTLFLAG_RD,
     &reass_path6, "Took path 6");
 
 counter_u64_t reass_path7;
 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path7, CTLFLAG_RD,
     &reass_path7, "Took path 7");
 
 counter_u64_t reass_fullwalk;
 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, fullwalk, CTLFLAG_RD,
     &reass_fullwalk, "Took a full walk ");
 
 counter_u64_t reass_nospace;
 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, nospace, CTLFLAG_RD,
     &reass_nospace, "Had no mbuf capacity ");
 
 counter_u64_t merge_fwd;
 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, merge_fwd, CTLFLAG_RD,
     &merge_fwd, "Ran merge fwd");
 
 counter_u64_t merge_into;
 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, merge_into, CTLFLAG_RD,
     &merge_into, "Ran merge into");
 
 counter_u64_t tcp_zero_input;
 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, zero_input, CTLFLAG_RD,
     &tcp_zero_input, "The reassembly buffer saw a zero len segment etc");
 
 #endif
 
 /* Initialize TCP reassembly queue */
 static void
 tcp_reass_zone_change(void *tag)
 {
 
 	/* Set the zone limit and read back the effective value. */
 	tcp_reass_maxseg = nmbclusters / 16;
 	tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone,
 	    tcp_reass_maxseg);
 }
 
 #ifdef TCP_REASS_LOGGING
 
 static void
 tcp_log_reassm(struct tcpcb *tp, struct tseg_qent *q, struct tseg_qent *p,
     tcp_seq seq, int len, uint8_t action, int instance)
 {
 	uint32_t cts;
 	struct timeval tv;
 
 	if (tp->t_logstate != TCP_LOG_STATE_OFF) {
 		union tcp_log_stackspecific log;
 
 		memset(&log, 0, sizeof(log));
 		cts = tcp_get_usecs(&tv);
 		log.u_bbr.flex1 = seq;
 		log.u_bbr.cur_del_rate = (uint64_t)q;
 		log.u_bbr.delRate = (uint64_t)p;
 		if (q != NULL) {
 			log.u_bbr.flex2 = q->tqe_start;
 			log.u_bbr.flex3 = q->tqe_len;
 			log.u_bbr.flex4 = q->tqe_mbuf_cnt;
 			log.u_bbr.hptsi_gain = q->tqe_flags;
 		}
 		if (p != NULL)  {
 			log.u_bbr.flex5 = p->tqe_start;
 			log.u_bbr.pkts_out = p->tqe_len;
 			log.u_bbr.epoch = p->tqe_mbuf_cnt;
 			log.u_bbr.cwnd_gain = p->tqe_flags;
 		}
 		log.u_bbr.flex6 = tp->t_segqmbuflen;
 		log.u_bbr.flex7 = instance;
 		log.u_bbr.flex8 = action;
 		log.u_bbr.timeStamp = cts;
 		TCP_LOG_EVENTP(tp, NULL,
 		    &tp->t_inpcb->inp_socket->so_rcv,
 		    &tp->t_inpcb->inp_socket->so_snd,
 		    TCP_LOG_REASS, 0,
 		    len, &log, false, &tv);
 	}
 }
 
 static void
 tcp_reass_log_dump(struct tcpcb *tp)
 {
 	struct tseg_qent *q;
 
 	if (tp->t_logstate != TCP_LOG_STATE_OFF) {
 		TAILQ_FOREACH(q, &tp->t_segq, tqe_q) {
 			tcp_log_reassm(tp, q, NULL, q->tqe_start, q->tqe_len, TCP_R_LOG_DUMP, 0);
 		}
 	};
 }
 
 static void
 tcp_reass_log_new_in(struct tcpcb *tp, tcp_seq seq, int len, struct mbuf *m,
     int logval, struct tseg_qent *q)
 {
 	int cnt;
 	struct mbuf *t;
 
 	cnt = 0;
 	t = m;
 	while (t) {
 		cnt += t->m_len;
 		t = t->m_next;
 	}
 	tcp_log_reassm(tp, q, NULL, seq, len, logval, cnt);
 }
 
 #endif
 
 void
 tcp_reass_global_init(void)
 {
 
 	tcp_reass_maxseg = nmbclusters / 16;
 	TUNABLE_INT_FETCH("net.inet.tcp.reass.maxsegments",
 	    &tcp_reass_maxseg);
 	tcp_reass_zone = uma_zcreate("tcpreass", sizeof (struct tseg_qent),
 	    NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
 	/* Set the zone limit and read back the effective value. */
 	tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone,
 	    tcp_reass_maxseg);
 #ifdef TCP_REASS_COUNTERS
 	reass_path1 = counter_u64_alloc(M_WAITOK);
 	reass_path2 = counter_u64_alloc(M_WAITOK);
 	reass_path3 = counter_u64_alloc(M_WAITOK);
 	reass_path4 = counter_u64_alloc(M_WAITOK);
 	reass_path5 = counter_u64_alloc(M_WAITOK);
 	reass_path6 = counter_u64_alloc(M_WAITOK);
 	reass_path7 = counter_u64_alloc(M_WAITOK);
 	reass_fullwalk = counter_u64_alloc(M_WAITOK);
 	reass_nospace = counter_u64_alloc(M_WAITOK);
 	reass_entry = counter_u64_alloc(M_WAITOK);
 	merge_fwd = counter_u64_alloc(M_WAITOK);
 	merge_into = counter_u64_alloc(M_WAITOK);
 	tcp_zero_input = counter_u64_alloc(M_WAITOK);
 #endif
 	EVENTHANDLER_REGISTER(nmbclusters_change,
 	    tcp_reass_zone_change, NULL, EVENTHANDLER_PRI_ANY);
 
 }
 
 void
 tcp_reass_flush(struct tcpcb *tp)
 {
 	struct tseg_qent *qe;
 
 	INP_WLOCK_ASSERT(tp->t_inpcb);
 
 	while ((qe = TAILQ_FIRST(&tp->t_segq)) != NULL) {
 		TAILQ_REMOVE(&tp->t_segq, qe, tqe_q);
 		m_freem(qe->tqe_m);
 		uma_zfree(tcp_reass_zone, qe);
 		tp->t_segqlen--;
 	}
 	tp->t_segqmbuflen = 0;
 	KASSERT((tp->t_segqlen == 0),
 	    ("TCP reass queue %p segment count is %d instead of 0 after flush.",
 	    tp, tp->t_segqlen));
 }
 
 static void
 tcp_reass_append(struct tcpcb *tp, struct tseg_qent *last,
     struct mbuf *m, struct tcphdr *th, int tlen, 
     struct mbuf *mlast, int lenofoh)
 {
 
 #ifdef TCP_REASS_LOGGING
 	tcp_log_reassm(tp, last, NULL, th->th_seq, tlen, TCP_R_LOG_APPEND, 0);
 #endif
 	last->tqe_len += tlen;
 	last->tqe_m->m_pkthdr.len += tlen;
 	/* Preserve the FIN bit if its there */
 	last->tqe_flags |= (th->th_flags & TH_FIN);
 	last->tqe_last->m_next = m;
 	last->tqe_last = mlast;
 	last->tqe_mbuf_cnt += lenofoh;
 	tp->t_rcvoopack++;
 	TCPSTAT_INC(tcps_rcvoopack);
 	TCPSTAT_ADD(tcps_rcvoobyte, tlen);
 #ifdef TCP_REASS_LOGGING
 	tcp_reass_log_new_in(tp, last->tqe_start, lenofoh, last->tqe_m,
 			     TCP_R_LOG_APPEND,
 			     last);
 #endif
 }
 
 static void
 tcp_reass_prepend(struct tcpcb *tp, struct tseg_qent *first, struct mbuf *m, struct tcphdr *th,
 		  int tlen, struct mbuf *mlast, int lenofoh)
 {
 	int i;
 	
 #ifdef TCP_REASS_LOGGING
 	tcp_log_reassm(tp, first, NULL, th->th_seq, tlen, TCP_R_LOG_PREPEND, 0);
 #endif
 	if (SEQ_GT((th->th_seq + tlen), first->tqe_start)) {
 		/* The new data overlaps into the old */
 		i = (th->th_seq + tlen) - first->tqe_start;
 #ifdef TCP_REASS_LOGGING
 		tcp_log_reassm(tp, first, NULL, 0, i, TCP_R_LOG_TRIM, 1);
 #endif
 		m_adj(first->tqe_m, i);
 		first->tqe_len -= i;
 		first->tqe_start += i;
 	}
 	/* Ok now setup our chain to point to the old first */
 	mlast->m_next = first->tqe_m;
 	first->tqe_m = m;
 	first->tqe_len += tlen;
 	first->tqe_start = th->th_seq;
 	first->tqe_m->m_pkthdr.len = first->tqe_len;
 	first->tqe_mbuf_cnt += lenofoh;
 	tp->t_rcvoopack++;
 	TCPSTAT_INC(tcps_rcvoopack);
 	TCPSTAT_ADD(tcps_rcvoobyte, tlen);
 #ifdef TCP_REASS_LOGGING
 	tcp_reass_log_new_in(tp, first->tqe_start, lenofoh, first->tqe_m,
 			     TCP_R_LOG_PREPEND,
 			     first);
 #endif
 }
 
 static void 
 tcp_reass_replace(struct tcpcb *tp, struct tseg_qent *q, struct mbuf *m,
     tcp_seq seq, int len, struct mbuf *mlast, int mbufoh, uint8_t flags)
 {
 	/*
 	 * Free the data in q, and replace
 	 * it with the new segment.
 	 */
 	int len_dif;
 
 #ifdef TCP_REASS_LOGGING
 	tcp_log_reassm(tp, q, NULL, seq, len, TCP_R_LOG_REPLACE, 0);
 #endif
 	m_freem(q->tqe_m);
 	KASSERT(tp->t_segqmbuflen >= q->tqe_mbuf_cnt,
 		("Tp:%p seg queue goes negative", tp));
 	tp->t_segqmbuflen -= q->tqe_mbuf_cnt;		       
 	q->tqe_mbuf_cnt = mbufoh;
 	q->tqe_m = m;
 	q->tqe_last = mlast;
 	q->tqe_start = seq;
 	if (len > q->tqe_len)
 		len_dif = len - q->tqe_len;
 	else
 		len_dif = 0;
 	tp->t_rcvoopack++;
 	TCPSTAT_INC(tcps_rcvoopack);
 	TCPSTAT_ADD(tcps_rcvoobyte, len_dif);
 	q->tqe_len = len;
 	q->tqe_flags = (flags & TH_FIN);
 	q->tqe_m->m_pkthdr.len = q->tqe_len;
 	tp->t_segqmbuflen += mbufoh;
 
 }
 
 static void
 tcp_reass_merge_into(struct tcpcb *tp, struct tseg_qent *ent,
     struct tseg_qent *q)
 {
 	/* 
 	 * Merge q into ent and free q from the list.
 	 */
 #ifdef TCP_REASS_LOGGING
 	tcp_log_reassm(tp, q, ent, 0, 0, TCP_R_LOG_MERGE_INTO, 0);
 #endif
 #ifdef TCP_REASS_COUNTERS
 	counter_u64_add(merge_into, 1);
 #endif
 	ent->tqe_last->m_next = q->tqe_m;
 	ent->tqe_last = q->tqe_last;
 	ent->tqe_len += q->tqe_len;
 	ent->tqe_mbuf_cnt += q->tqe_mbuf_cnt;
 	ent->tqe_m->m_pkthdr.len += q->tqe_len;
 	ent->tqe_flags |= (q->tqe_flags & TH_FIN);
 	TAILQ_REMOVE(&tp->t_segq, q, tqe_q);
 	uma_zfree(tcp_reass_zone, q);
 	tp->t_segqlen--;
 
 }
 
 static void
 tcp_reass_merge_forward(struct tcpcb *tp, struct tseg_qent *ent)
 {
 	struct tseg_qent *q, *qtmp;
 	int i;
 	tcp_seq max;
 	/*
 	 * Given an entry merge forward anyplace
 	 * that ent overlaps forward.
 	 */
 
 	max = ent->tqe_start + ent->tqe_len;
 	q = TAILQ_NEXT(ent, tqe_q);
 	if (q == NULL) {
 		/* Nothing left */
 		return;
 	}
 	TAILQ_FOREACH_FROM_SAFE(q, &tp->t_segq, tqe_q, qtmp) {
 		if (SEQ_GT(q->tqe_start, max)) {
 			/* Beyond q */
 			break;
 		}
 		/* We have some or all that are overlapping */
 		if (SEQ_GEQ(max, (q->tqe_start + q->tqe_len))) {
 			/* It consumes it all */
 			tp->t_segqmbuflen -= q->tqe_mbuf_cnt;
 			m_freem(q->tqe_m);
 			TAILQ_REMOVE(&tp->t_segq, q, tqe_q);
 			uma_zfree(tcp_reass_zone, q);
 			tp->t_segqlen--;
 			continue;
 		}
 		/* 
 		 * Trim the q entry to dovetail to this one 
 		 * and then merge q into ent updating max
 		 * in the process.
 		 */
 		i = max - q->tqe_start;
 #ifdef TCP_REASS_LOGGING
 		tcp_log_reassm(tp, q, NULL, 0, i, TCP_R_LOG_TRIM, 2);
 #endif
 		m_adj(q->tqe_m, i);
 		q->tqe_len -= i;
 		q->tqe_start += i;
 		tcp_reass_merge_into(tp, ent, q);
 		max = ent->tqe_start + ent->tqe_len;
 	}
 #ifdef TCP_REASS_COUNTERS
 	counter_u64_add(merge_fwd, 1);
 #endif
 }
 
 static int 
 tcp_reass_overhead_of_chain(struct mbuf *m, struct mbuf **mlast)
 {
 	int len = MSIZE;
 
 	if (m->m_flags & M_EXT)
 		len += m->m_ext.ext_size;
 	while (m->m_next != NULL) {
 		m = m->m_next;
 		len += MSIZE;
 		if (m->m_flags & M_EXT)
 			len += m->m_ext.ext_size;
 	}
 	*mlast = m;
 	return (len);
 }
 
 
 /*
  * NOTE!!! the new tcp-reassembly code *must not* use
  * m_adj() with a negative index. That alters the chain
  * of mbufs (by possibly chopping trailing mbufs). At
  * the front of tcp_reass we count the mbuf overhead
  * and setup the tail pointer. If we use m_adj(m, -5)
  * we could corrupt the tail pointer. Currently the
  * code only uses m_adj(m, postive-num). If this
  * changes appropriate changes to update mlast would
  * be needed.
  */
 int
 tcp_reass(struct tcpcb *tp, struct tcphdr *th, tcp_seq *seq_start,
 	  int *tlenp, struct mbuf *m)
 {
 	struct tseg_qent *q, *last, *first;
 	struct tseg_qent *p = NULL;
 	struct tseg_qent *nq = NULL;
 	struct tseg_qent *te = NULL;
-	struct tseg_qent tqs;
 	struct mbuf *mlast = NULL;
 	struct sockbuf *sb;
 	struct socket *so = tp->t_inpcb->inp_socket;
 	char *s = NULL;
 	int flags, i, lenofoh;
 
 	INP_WLOCK_ASSERT(tp->t_inpcb);
 	/*
 	 * XXX: tcp_reass() is rather inefficient with its data structures
 	 * and should be rewritten (see NetBSD for optimizations).
 	 */
 
 	/*
 	 * Call with th==NULL after become established to
 	 * force pre-ESTABLISHED data up to user socket.
 	 */
 	if (th == NULL)
 		goto present;
 	KASSERT(SEQ_GEQ(th->th_seq, tp->rcv_nxt),
 		("Attempt to add old entry to reassembly queue (th=%p, tp=%p)",
 		 th, tp));
 #ifdef TCP_REASS_LOGGING
 	tcp_reass_log_new_in(tp, th->th_seq, *tlenp, m, TCP_R_LOG_ADD, NULL);
 #endif
 #ifdef TCP_REASS_COUNTERS
 	counter_u64_add(reass_entry, 1);
 #endif
 	/*
 	 * Check for zero length data.
 	 */
 	if ((*tlenp == 0) && ((th->th_flags & TH_FIN) == 0)) {
 		/*
 		 * A zero length segment does no
 		 * one any good. We could check
 		 * the rcv_nxt <-> rcv_wnd but thats
 		 * already done for us by the caller.
 		 */
 #ifdef TCP_REASS_COUNTERS 
 		counter_u64_add(tcp_zero_input, 1);
 #endif
 		m_freem(m);
 #ifdef TCP_REASS_LOGGING
 		tcp_reass_log_dump(tp);
 #endif
 		return (0);
 	}
 	/*
 	 * Will it fit?
 	 */
 	lenofoh = tcp_reass_overhead_of_chain(m, &mlast);
 	sb = &tp->t_inpcb->inp_socket->so_rcv;
 	if ((sb->sb_mbcnt + tp->t_segqmbuflen + lenofoh) > sb->sb_mbmax) {
 		/* No room */
 		TCPSTAT_INC(tcps_rcvreassfull);
 #ifdef TCP_REASS_COUNTERS
 		counter_u64_add(reass_nospace, 1);
 #endif
 #ifdef TCP_REASS_LOGGING
 		tcp_log_reassm(tp, NULL, NULL, th->th_seq, lenofoh, TCP_R_LOG_LIMIT_REACHED, 0);
 #endif
 		m_freem(m);
 		*tlenp = 0;
 #ifdef TCP_REASS_LOGGING
 		tcp_reass_log_dump(tp);
 #endif
 		return (0);
 	}
 	/*
 	 * First lets deal with two common cases, the
 	 * segment appends to the back of our collected
 	 * segments. Or the segment is the next in line.
 	 */
 	last = TAILQ_LAST_FAST(&tp->t_segq, tseg_qent, tqe_q);
 	if (last != NULL) {
 		if ((th->th_flags & TH_FIN) &&
 		    SEQ_LT((th->th_seq + *tlenp), (last->tqe_start + last->tqe_len))) {
 			/* 
 			 * Someone is trying to game us, dump
 			 * the segment.
 			 */
 			*tlenp = 0;
 			m_freem(m);
 			return (0);
 		}
 		if ((SEQ_GEQ(th->th_seq, last->tqe_start)) &&
 		    (SEQ_GEQ((last->tqe_start + last->tqe_len), th->th_seq))) {
 			/* Common case, trailing segment is added */
 			/**
 			 *                                 +--last
 			 *                                 v
 			 *  reassembly buffer |---|  |---| |---|
 			 *  new segment                       |---|
 			 */
 #ifdef TCP_REASS_COUNTERS
 			counter_u64_add(reass_path1, 1);
 #endif
 			if (SEQ_GT((last->tqe_start + last->tqe_len), th->th_seq)) {
 				i = (last->tqe_start + last->tqe_len) - th->th_seq;
 				if (i < *tlenp) {
 #ifdef TCP_REASS_LOGGING
 					tcp_log_reassm(tp, last, NULL, 0, i, TCP_R_LOG_TRIM, 3);
 					th->th_seq += i;
 #endif
 					m_adj(m, i);
 					*tlenp -= i;
 				} else {
 					/* Complete overlap */
 					TCPSTAT_INC(tcps_rcvduppack);
 					TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp);
 					m_freem(m);
 					*tlenp = last->tqe_len;
 					*seq_start = last->tqe_start;
 					return (0);
 				}
 			}
 			if (last->tqe_flags & TH_FIN) {
 				/* 
 				 * We have data after the FIN on the last? 
 				 */
 				*tlenp = 0;
 				m_freem(m);
 				return(0);
 			}
 			tcp_reass_append(tp, last, m, th, *tlenp, mlast, lenofoh);
 			tp->t_segqmbuflen += lenofoh;
 			*seq_start = last->tqe_start;
 			*tlenp = last->tqe_len;
 			return (0);
 		} else if (SEQ_GT(th->th_seq, (last->tqe_start + last->tqe_len))) {
 			/* 
 			 * Second common case, we missed
 			 * another one and have something more
 			 * for the end.
 			 */
 			/**
 			 *                                 +--last
 			 *                                 v
 			 *  reassembly buffer |---|  |---| |---|
 			 *  new segment                           |---|
 			 */
 			if (last->tqe_flags & TH_FIN) {
 				/* 
 				 * We have data after the FIN on the last? 
 				 */
 				*tlenp = 0;
 				m_freem(m);
 				return(0);
 			}
 #ifdef TCP_REASS_COUNTERS
 			counter_u64_add(reass_path2, 1);
 #endif
 			p = last;
 			goto new_entry;
 		}
 	} else {
 		/* First segment (it's NULL). */
 		goto new_entry;
 	}
 	first = TAILQ_FIRST(&tp->t_segq);
 	if (SEQ_LT(th->th_seq, first->tqe_start) &&
 	    SEQ_GEQ((th->th_seq + *tlenp),first->tqe_start) &&
 	    SEQ_LT((th->th_seq + *tlenp), (first->tqe_start + first->tqe_len))) {
 		/*
 		 * The head of the queue is prepended by this and
 		 * it may be the one I want most.
 		 */
 		/**
 		 *       first-------+
 		 *                   v
 		 *  rea:             |---|  |---| |---|
 		 *  new:         |---|
 		 * Note the case we do not deal with here is:
 		 *   rea=     |---|   |---|   |---|
 		 *   new=  |----|
 		 * Due to the fact that it could be
 		 *   new   |--------------------|
 		 * And we might need to merge forward.
 		 */
 #ifdef INVARIANTS
 		struct mbuf *firstmbuf;
 #endif
 
 #ifdef TCP_REASS_COUNTERS
 		counter_u64_add(reass_path3, 1);
 #endif
 		if (SEQ_LT(th->th_seq, tp->rcv_nxt)) {
 			/* 
 			 * The resend was even before 
 			 * what we have. We need to trim it.
 			 * Note TSNH (it should be trimmed
 			 * before the call to tcp_reass()).
 			 */
 #ifdef INVARIANTS
 			panic("th->th_seq:%u rcv_nxt:%u tp:%p not pre-trimmed",
 			      th->th_seq, tp->rcv_nxt, tp);
 #else
 			i = tp->rcv_nxt - th->th_seq;
 #ifdef TCP_REASS_LOGGING
 			tcp_log_reassm(tp, first, NULL, 0, i, TCP_R_LOG_TRIM, 4);
 #endif
 			m_adj(m, i);
 			th->th_seq += i;
 			*tlenp -= i;
 #endif
 		}
 #ifdef INVARIANTS
 		firstmbuf = first->tqe_m;
 #endif
 		tcp_reass_prepend(tp, first, m, th, *tlenp, mlast, lenofoh);
 #ifdef INVARIANTS
 		if (firstmbuf == first->tqe_m) {
 			panic("First stayed same m:%p foobar:%p first->tqe_m:%p tp:%p first:%p",
 			      m, firstmbuf, first->tqe_m, tp, first);
 		} else if (first->tqe_m != m) {
 			panic("First did not change to m:%p foobar:%p first->tqe_m:%p tp:%p first:%p",
 			      m, firstmbuf, first->tqe_m, tp, first);
 		}
 #endif
 		tp->t_segqmbuflen += lenofoh;
 		*seq_start = first->tqe_start;
 		*tlenp = first->tqe_len;
 		goto present;
 	} else if (SEQ_LT((th->th_seq + *tlenp), first->tqe_start)) {
 		/* New segment is before our earliest segment. */
 		/**
 		 *           first---->+
 		 *                      v
 		 *  rea=                |---| ....
 		 *  new"         |---|
 		 *
 		 */
 		goto new_entry;
 	}
 	/*
 	 * Find a segment which begins after this one does.
 	 */
 #ifdef TCP_REASS_COUNTERS
 	counter_u64_add(reass_fullwalk, 1);
 #endif
 	TAILQ_FOREACH(q, &tp->t_segq, tqe_q) {
 		if (SEQ_GT(q->tqe_start, th->th_seq))
 			break;
 	}
 	p = TAILQ_PREV(q, tsegqe_head, tqe_q);
 	/**
 	 * Now is this fit just in-between only? 
 	 * i.e.:
 	 *      p---+        +----q
 	 *          v        v
 	 *     res= |--|     |--|    |--|
 	 *     nee       |-|
 	 */
 	if (SEQ_LT((th->th_seq + *tlenp), q->tqe_start) &&
 	    ((p == NULL) || (SEQ_GT(th->th_seq, (p->tqe_start + p->tqe_len))))) {
 		/* Yep no overlap */
 		goto new_entry;
 	}
 	/**
 	 * If we reach here we have some (possibly all) overlap
 	 * such as:
 	 *     res=     |--|     |--|    |--|
 	 *     new=  |----|
 	 * or  new=  |-----------------|
 	 * or  new=      |--------|
 	 * or  new=            |---|
 	 * or  new=            |-----------|
 	 */
 	if ((p != NULL) &&
 	    (SEQ_LEQ(th->th_seq, (p->tqe_start + p->tqe_len)))) {
 		/* conversion to int (in i) handles seq wraparound */
 
 #ifdef TCP_REASS_COUNTERS
 		counter_u64_add(reass_path4, 1);
 #endif
 		i = p->tqe_start + p->tqe_len - th->th_seq;
 		if (i >= 0) {
 			if (i >= *tlenp) {
 				/**
 				 *       prev seg---->+
 				 *                    v
 				 *  reassembly buffer |---|
 				 *  new segment        |-|
 				 */
 				TCPSTAT_INC(tcps_rcvduppack);
 				TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp);
 				*tlenp = p->tqe_len;
 				*seq_start = p->tqe_start;
 				m_freem(m);
 				/*
 				 * Try to present any queued data
 				 * at the left window edge to the user.
 				 * This is needed after the 3-WHS
 				 * completes. Note this probably
 				 * will not work and we will return.
 				 */
 				return (0);
 			}
 			if (i > 0) {
 				/**
 				 *       prev seg---->+
 				 *                    v
 				 *  reassembly buffer |---|
 				 *  new segment         |-----|
 				 */
 #ifdef TCP_REASS_COUNTERS
 				counter_u64_add(reass_path5, 1);
 #endif
 #ifdef TCP_REASS_LOGGING
 				tcp_log_reassm(tp, p, NULL, 0, i, TCP_R_LOG_TRIM, 5);
 #endif
 				m_adj(m, i);
 				*tlenp -= i;
 				th->th_seq += i;
 			}
 		}
 		if (th->th_seq == (p->tqe_start + p->tqe_len)) {
 			/* 
 			 * If dovetails in with this one 
 			 * append it.
 			 */
 			/**
 			 *       prev seg---->+
 			 *                    v
 			 *  reassembly buffer |--|     |---|
 			 *  new segment          |--|
 			 * (note: it was trimmed above if it overlapped)
 			 */
 			tcp_reass_append(tp, p, m, th, *tlenp, mlast, lenofoh);
 			tp->t_segqmbuflen += lenofoh;
 		} else {
 #ifdef INVARIANTS
 			panic("Impossible cut th_seq:%u p->seq:%u(%d) p:%p tp:%p",
 			      th->th_seq, p->tqe_start, p->tqe_len,
 			      p, tp);
 #endif
 			*tlenp = 0;
 			m_freem(m);
 			return (0);
 		}
 		q = p;
 	} else {
 		/*
 		 * The new data runs over the 
 		 * top of previously sack'd data (in q).
 		 * It may be partially overlapping, or
 		 * it may overlap the entire segment.
 		 */
 #ifdef TCP_REASS_COUNTERS
 		counter_u64_add(reass_path6, 1);
 #endif
 		if (SEQ_GEQ((th->th_seq + *tlenp), (q->tqe_start + q->tqe_len))) {
 			/* It consumes it all */
 			/**
 			 *             next seg---->+
 			 *                          v
 			 *  reassembly buffer |--|     |---|
 			 *  new segment              |----------|
 			 */
 #ifdef TCP_REASS_COUNTERS
 			counter_u64_add(reass_path7, 1);
 #endif
 			tcp_reass_replace(tp, q, m, th->th_seq, *tlenp, mlast, lenofoh, th->th_flags);
 		} else {
 			/* 
 			 * We just need to prepend the data
 			 * to this. It does not overrun
 			 * the end.
 			 */
 			/**
 			 *                next seg---->+
 			 *                             v
 			 *  reassembly buffer |--|     |---|
 			 *  new segment                   |----------|
 			 */
 			tcp_reass_prepend(tp, q, m, th, *tlenp, mlast, lenofoh);
 			tp->t_segqmbuflen += lenofoh;
 		}
 	}
 	/* Now does it go further than that? */
 	tcp_reass_merge_forward(tp, q);
 	*seq_start = q->tqe_start;
 	*tlenp = q->tqe_len;
 	goto present;
 
 	/* 
 	 * When we reach here we can't combine it 
 	 * with any existing segment.
 	 *
 	 * Limit the number of segments that can be queued to reduce the
 	 * potential for mbuf exhaustion. For best performance, we want to be
 	 * able to queue a full window's worth of segments. The size of the
 	 * socket receive buffer determines our advertised window and grows
 	 * automatically when socket buffer autotuning is enabled. Use it as the
 	 * basis for our queue limit.
 	 *
 	 * However, allow the user to specify a ceiling for the number of
 	 * segments in each queue.
 	 *
 	 * Always let the missing segment through which caused this queue.
 	 * NB: Access to the socket buffer is left intentionally unlocked as we
 	 * can tolerate stale information here.
 	 *
 	 * XXXLAS: Using sbspace(so->so_rcv) instead of so->so_rcv.sb_hiwat
 	 * should work but causes packets to be dropped when they shouldn't.
 	 * Investigate why and re-evaluate the below limit after the behaviour
 	 * is understood.
 	 */
 new_entry:
 	if (tcp_new_limits) {
 		if ((tp->t_segqlen > tcp_reass_queue_guard) &&
 		    (*tlenp < MSIZE)) {
 			/* 
 			 * This is really a lie, we are not full but
 			 * are getting a segment that is above 
 			 * guard threshold. If it is and its below
 			 * a mbuf size (256) we drop it if it
 			 * can't fill in some place.
 			 */
 			TCPSTAT_INC(tcps_rcvreassfull);
 			*tlenp = 0;
 			if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, NULL))) {
 				log(LOG_DEBUG, "%s; %s: queue limit reached, "
 				    "segment dropped\n", s, __func__);
 				free(s, M_TCPLOG);
 			}
 			m_freem(m);
 #ifdef TCP_REASS_LOGGING
 			tcp_reass_log_dump(tp);
 #endif
 			return (0);
 		}
 	} else {
 
 		if ((th->th_seq != tp->rcv_nxt || !TCPS_HAVEESTABLISHED(tp->t_state)) &&
 		    tp->t_segqlen >= min((so->so_rcv.sb_hiwat / tp->t_maxseg) + 1,
 					 tcp_reass_maxqueuelen)) {
 			TCPSTAT_INC(tcps_rcvreassfull);
 			*tlenp = 0;
 			if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, NULL))) {
 				log(LOG_DEBUG, "%s; %s: queue limit reached, "
 				    "segment dropped\n", s, __func__);
 				free(s, M_TCPLOG);
 			}
 			m_freem(m);
 #ifdef TCP_REASS_LOGGING
 			tcp_reass_log_dump(tp);
 #endif
 			return (0);
 		}
 	}
 	/*
 	 * Allocate a new queue entry. If we can't, or hit the zone limit
 	 * just drop the pkt.
 	 */
 	te = uma_zalloc(tcp_reass_zone, M_NOWAIT);
 	if (te == NULL) {
 		TCPSTAT_INC(tcps_rcvmemdrop);
 		m_freem(m);
 		*tlenp = 0;
 		if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL,
 				       NULL))) {
 			log(LOG_DEBUG, "%s; %s: global zone limit "
 			    "reached, segment dropped\n", s, __func__);
 			free(s, M_TCPLOG);
 		}
 		return (0);
 	}
 	tp->t_segqlen++;
 	tp->t_rcvoopack++;
 	TCPSTAT_INC(tcps_rcvoopack);
 	TCPSTAT_ADD(tcps_rcvoobyte, *tlenp);
 	/* Insert the new segment queue entry into place. */
 	te->tqe_m = m;
 	te->tqe_flags = th->th_flags;
 	te->tqe_len = *tlenp;
 	te->tqe_start = th->th_seq;
 	te->tqe_last = mlast;
 	te->tqe_mbuf_cnt = lenofoh;
 	tp->t_segqmbuflen += te->tqe_mbuf_cnt;
 	if (p == NULL) {
 		TAILQ_INSERT_HEAD(&tp->t_segq, te, tqe_q);
 	} else {
 		TAILQ_INSERT_AFTER(&tp->t_segq, p, te, tqe_q);
 	}
 #ifdef TCP_REASS_LOGGING
 	tcp_reass_log_new_in(tp, th->th_seq, *tlenp, m, TCP_R_LOG_NEW_ENTRY, te);
 #endif
 present:
 	/*
 	 * Present data to user, advancing rcv_nxt through
 	 * completed sequence space.
 	 */
 	if (!TCPS_HAVEESTABLISHED(tp->t_state))
 		return (0);
 	q = TAILQ_FIRST(&tp->t_segq);
 	KASSERT(q == NULL || SEQ_GEQ(q->tqe_start, tp->rcv_nxt),
 		("Reassembly queue for %p has stale entry at head", tp));
 	if (!q || q->tqe_start != tp->rcv_nxt) {
 #ifdef TCP_REASS_LOGGING
 		tcp_reass_log_dump(tp);
 #endif
 		return (0);
 	}
 	SOCKBUF_LOCK(&so->so_rcv);
 	do {
 		tp->rcv_nxt += q->tqe_len;
 		flags = q->tqe_flags & TH_FIN;
 		nq = TAILQ_NEXT(q, tqe_q);
 		TAILQ_REMOVE(&tp->t_segq, q, tqe_q);
 		if (so->so_rcv.sb_state & SBS_CANTRCVMORE) {
 			m_freem(q->tqe_m);
 		} else {
 #ifdef TCP_REASS_LOGGING
 			tcp_reass_log_new_in(tp, q->tqe_start, q->tqe_len, q->tqe_m, TCP_R_LOG_READ, q);
 			tcp_log_reassm(tp, q, NULL, th->th_seq, *tlenp, TCP_R_LOG_READ, 1);
 #endif
 			sbappendstream_locked(&so->so_rcv, q->tqe_m, 0);
 		}
 #ifdef TCP_REASS_LOGGING
 		tcp_log_reassm(tp, q, NULL, th->th_seq, *tlenp, TCP_R_LOG_READ, 2);
 #endif
 		KASSERT(tp->t_segqmbuflen >= q->tqe_mbuf_cnt,
 			("tp:%p seg queue goes negative", tp));
 		tp->t_segqmbuflen -= q->tqe_mbuf_cnt;
-		if (q != &tqs) 
-			uma_zfree(tcp_reass_zone, q);
+		uma_zfree(tcp_reass_zone, q);
 		tp->t_segqlen--;
 		q = nq;
 	} while (q && q->tqe_start == tp->rcv_nxt);
 	if (TAILQ_EMPTY(&tp->t_segq) &&
 	    (tp->t_segqmbuflen != 0)) {
 #ifdef INVARIANTS
 		panic("tp:%p segq:%p len:%d queue empty",
 		      tp, &tp->t_segq, tp->t_segqmbuflen);
 #else
 #ifdef TCP_REASS_LOGGING
 		tcp_log_reassm(tp, NULL, NULL, th->th_seq, *tlenp, TCP_R_LOG_ZERO, 0);
 #endif
 		tp->t_segqmbuflen = 0;
 #endif
 	}
 #ifdef TCP_REASS_LOGGING
 	tcp_reass_log_dump(tp);
 #endif
 	sorwakeup_locked(so);
 	return (flags);
 }