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tcp: Restore correct ECT marking behavior on SACK retransmissions

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While coalescing all ECN-related code into new common source files,
the flag to deal with SACK retransmissions was skipped. This leads
to non-compliant ECT-marking of SACK retransmissions, as well as
the premature sending of other TCP ECN flags (CWR).

Reviewed By: rrs, #transport
Sponsored by:        NetApp, Inc.
Differential Revision: https://reviews.freebsd.org/D34376
This commit is contained in:
Richard Scheffenegger 2022-02-25 20:05:15 +01:00
parent c84bb8cd77
commit 2ff07d9220
4 changed files with 7 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
sys/netinet/tcp_ecn.c
View File

@ -201,7 +201,7 @@ tcp_ecn_output_syn_sent(struct tcpcb *tp)
* returning IP ECN header codepoint
*/
int
tcp_ecn_output_established(struct tcpcb *tp, uint16_t *thflags, int len)
tcp_ecn_output_established(struct tcpcb *tp, uint16_t *thflags, int len, bool rxmit)
{
int ipecn = IPTOS_ECN_NOTECT;
bool newdata;
@ -213,6 +213,7 @@ tcp_ecn_output_established(struct tcpcb *tp, uint16_t *thflags, int len)
* and window probes.
*/
newdata = (len > 0 && SEQ_GEQ(tp->snd_nxt, tp->snd_max) &&
!rxmit &&
!((tp->t_flags & TF_FORCEDATA) && len == 1));
if (newdata) {
ipecn = IPTOS_ECN_ECT0;

2
sys/netinet/tcp_ecn.h
View File

@ -45,7 +45,7 @@ void tcp_ecn_input_syn_sent(struct tcpcb *, uint16_t, int);
void tcp_ecn_input_parallel_syn(struct tcpcb *, uint16_t, int);
int tcp_ecn_input_segment(struct tcpcb *, uint16_t, int);
uint16_t tcp_ecn_output_syn_sent(struct tcpcb *);
int tcp_ecn_output_established(struct tcpcb *, uint16_t *, int);
int tcp_ecn_output_established(struct tcpcb *, uint16_t *, int, bool);
void tcp_ecn_syncache_socket(struct tcpcb *, struct syncache *);
int tcp_ecn_syncache_add(uint16_t, int);
uint16_t tcp_ecn_syncache_respond(uint16_t, struct syncache *);

2
sys/netinet/tcp_output.c
View File

@ -1206,7 +1206,7 @@ tcp_default_output(struct tcpcb *tp)
/* Also handle parallel SYN for ECN */
if ((TCPS_HAVERCVDSYN(tp->t_state)) &&
(tp->t_flags2 & TF2_ECN_PERMIT)) {
int ect = tcp_ecn_output_established(tp, &flags, len);
int ect = tcp_ecn_output_established(tp, &flags, len, sack_rxmit);
if ((tp->t_state == TCPS_SYN_RECEIVED) &&
(tp->t_flags2 & TF2_ECN_SND_ECE))
tp->t_flags2 &= ~TF2_ECN_SND_ECE;

6
sys/netinet/tcp_stacks/rack.c
View File

@ -15742,7 +15742,7 @@ rack_fast_rsm_output(struct tcpcb *tp, struct tcp_rack *rack, struct rack_sendma
m->m_pkthdr.rcvif = (struct ifnet *)0;
if (TCPS_HAVERCVDSYN(tp->t_state) &&
(tp->t_flags2 & TF2_ECN_PERMIT)) {
int ect = tcp_ecn_output_established(tp, &flags, len);
int ect = tcp_ecn_output_established(tp, &flags, len, true);
if ((tp->t_state == TCPS_SYN_RECEIVED) &&
(tp->t_flags2 & TF2_ECN_SND_ECE))
tp->t_flags2 &= ~TF2_ECN_SND_ECE;
@ -16233,7 +16233,7 @@ rack_fast_output(struct tcpcb *tp, struct tcp_rack *rack, uint64_t ts_val,
m->m_pkthdr.rcvif = (struct ifnet *)0;
if (TCPS_HAVERCVDSYN(tp->t_state) &&
(tp->t_flags2 & TF2_ECN_PERMIT)) {
int ect = tcp_ecn_output_established(tp, &flags, len);
int ect = tcp_ecn_output_established(tp, &flags, len, false);
if ((tp->t_state == TCPS_SYN_RECEIVED) &&
(tp->t_flags2 & TF2_ECN_SND_ECE))
tp->t_flags2 &= ~TF2_ECN_SND_ECE;
@ -18278,7 +18278,7 @@ rack_output(struct tcpcb *tp)
/* Also handle parallel SYN for ECN */
if (TCPS_HAVERCVDSYN(tp->t_state) &&
(tp->t_flags2 & TF2_ECN_PERMIT)) {
int ect = tcp_ecn_output_established(tp, &flags, len);
int ect = tcp_ecn_output_established(tp, &flags, len, sack_rxmit);
if ((tp->t_state == TCPS_SYN_RECEIVED) &&
(tp->t_flags2 & TF2_ECN_SND_ECE))
tp->t_flags2 &= ~TF2_ECN_SND_ECE;