git: 7ebfafa813ce - stable/14 - tcp: fix conversion of rttvar

The branch stable/14 has been updated by tuexen:

URL: https://cgit.FreeBSD.org/src/commit/?id=7ebfafa813ce89b2082647eb1c9e136b527ce653

commit 7ebfafa813ce89b2082647eb1c9e136b527ce653
Author:     Michael Tuexen <tuexen@FreeBSD.org>
AuthorDate: 2024-04-03 16:39:31 +0000
Commit:     Michael Tuexen <tuexen@FreeBSD.org>
CommitDate: 2024-04-17 13:53:15 +0000

    tcp: fix conversion of rttvar
    
    A wrong variable and wrong scaling factors were used.
    
    Reported by:            Coverity Scan
    CID:                    1508689
    Reviewed by:            rscheff
    Sponsored by:           Netflix, Inc.
    Differential Revision:  https://reviews.freebsd.org/D44612
    
    (cherry picked from commit e0bd180130b8c95f568483d0df6abff00d7d2153)
---
 sys/netinet/tcp_subr.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/sys/netinet/tcp_subr.c b/sys/netinet/tcp_subr.c
index 34150707072e..c11bfce889e6 100644
--- a/sys/netinet/tcp_subr.c
+++ b/sys/netinet/tcp_subr.c
@@ -4201,19 +4201,19 @@ tcp_change_time_units(struct tcpcb *tp, int granularity)
 			uint32_t val, frac;
 
 			val = USEC_2_TICKS(tp->t_rttvar);
-			frac = tp->t_srtt % (HPTS_USEC_IN_SEC / hz);
+			frac = tp->t_rttvar % (HPTS_USEC_IN_SEC / hz);
 			tp->t_rttvar = val <<  TCP_RTTVAR_SHIFT;
 			/*
 			 * frac is the fractional part here is left
 			 * over from converting to hz and shifting.
-			 * We need to convert this to the 5 bit
+			 * We need to convert this to the 4 bit
 			 * remainder.
 			 */
 			if (frac) {
 				if (hz == 1000) {
-					frac = (((uint64_t)frac *  (uint64_t)TCP_RTT_SCALE) / (uint64_t)HPTS_USEC_IN_MSEC);
+					frac = (((uint64_t)frac *  (uint64_t)TCP_RTTVAR_SCALE) / (uint64_t)HPTS_USEC_IN_MSEC);
 				} else {
-					frac = (((uint64_t)frac * (uint64_t)(hz) * (uint64_t)TCP_RTT_SCALE) /(uint64_t)HPTS_USEC_IN_SEC);
+					frac = (((uint64_t)frac * (uint64_t)(hz) * (uint64_t)TCP_RTTVAR_SCALE) /(uint64_t)HPTS_USEC_IN_SEC);
 				}
 				tp->t_rttvar += frac;
 			}