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Date:      Tue, 4 Dec 2018 22:05:36 +0000 (UTC)
From:      Michael Tuexen <tuexen@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-12@freebsd.org
Subject:   svn commit: r341497 - stable/12/sys/netinet/tcp_stacks
Message-ID:  <201812042205.wB4M5ahT093148@repo.freebsd.org>
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Author: tuexen
Date: Tue Dec  4 22:05:36 2018
New Revision: 341497
URL: https://svnweb.freebsd.org/changeset/base/341497

Log:
  MFC r340738:
  
  Improve two KASSERTs in the TCP RACK stack.
  
  There are two locations where an always true comparison was made in
  a KASSERT. Replace this by an appropriate check and use a consistent
  panic message. Also use this code when checking a similar condition.
  
  PR:			229664
  Reviewed by:		rrs@
  MFC after:		1 week
  Sponsored by:		Netflix, Inc.
  Differential Revision:	https://reviews.freebsd.org/D18021

Modified:
  stable/12/sys/netinet/tcp_stacks/rack.c
Directory Properties:
  stable/12/   (props changed)

Modified: stable/12/sys/netinet/tcp_stacks/rack.c
==============================================================================
--- stable/12/sys/netinet/tcp_stacks/rack.c	Tue Dec  4 21:57:26 2018	(r341496)
+++ stable/12/sys/netinet/tcp_stacks/rack.c	Tue Dec  4 22:05:36 2018	(r341497)
@@ -7053,12 +7053,10 @@ again:
 		tlen = rsm->r_end - rsm->r_start;
 		if (tlen > tp->t_maxseg)
 			tlen = tp->t_maxseg;
-#ifdef INVARIANTS
-		if (SEQ_GT(tp->snd_una, rsm->r_start)) {
-			panic("tp:%p rack:%p snd_una:%u rsm:%p r_start:%u",
-			    tp, rack, tp->snd_una, rsm, rsm->r_start);
-		}
-#endif
+		KASSERT(SEQ_LEQ(tp->snd_una, rsm->r_start),
+		    ("%s:%d: r.start:%u < SND.UNA:%u; tp:%p, rack:%p, rsm:%p",
+		    __func__, __LINE__,
+		    rsm->r_start, tp->snd_una, tp, rack, rsm));
 		sb_offset = rsm->r_start - tp->snd_una;
 		cwin = min(tp->snd_wnd, tlen);
 		len = cwin;
@@ -7069,12 +7067,14 @@ again:
 		len = rsm->r_end - rsm->r_start;
 		sack_rxmit = 1;
 		sendalot = 0;
+		KASSERT(SEQ_LEQ(tp->snd_una, rsm->r_start),
+		    ("%s:%d: r.start:%u < SND.UNA:%u; tp:%p, rack:%p, rsm:%p",
+		    __func__, __LINE__,
+		    rsm->r_start, tp->snd_una, tp, rack, rsm));
 		sb_offset = rsm->r_start - tp->snd_una;
 		if (len >= tp->t_maxseg) {
 			len = tp->t_maxseg;
 		}
-		KASSERT(sb_offset >= 0, ("%s: sack block to the left of una : %d",
-		    __func__, sb_offset));
 	} else if ((rack->rc_in_persist == 0) &&
 	    ((rsm = tcp_rack_output(tp, rack, cts)) != NULL)) {
 		long tlen;
@@ -7099,6 +7099,10 @@ again:
 		}
 #endif
 		tlen = rsm->r_end - rsm->r_start;
+		KASSERT(SEQ_LEQ(tp->snd_una, rsm->r_start),
+		    ("%s:%d: r.start:%u < SND.UNA:%u; tp:%p, rack:%p, rsm:%p",
+		    __func__, __LINE__,
+		    rsm->r_start, tp->snd_una, tp, rack, rsm));
 		sb_offset = rsm->r_start - tp->snd_una;
 		if (tlen > rack->r_ctl.rc_prr_sndcnt) {
 			len = rack->r_ctl.rc_prr_sndcnt;
@@ -7120,8 +7124,6 @@ again:
 				goto just_return_nolock;
 			}
 		}
-		KASSERT(sb_offset >= 0, ("%s: sack block to the left of una : %d",
-		    __func__, sb_offset));
 		if (len > 0) {
 			sub_from_prr = 1;
 			sack_rxmit = 1;

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