d/freebsd-skq
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Correctly set up the initial TCP congestion window in all cases,

Browse Source 
by not including the SYN bit sequence space in cwnd related calculations.
Snd_und is adjusted explicitly in all cases, outside the cwnd update, instead.

This fixes an off-by-one conformance issue with regular TCP sessions not
using Appropriate Byte Counting (RFC3465), sending one more packet during
the initial window than expected.

PR:		235256
Reviewed by:	tuexen (mentor), rgrimes (mentor)
Approved by:	tuexen (mentor), rgrimes (mentor)
MFC after:	3 weeks
Sponsored by:	NetApp, Inc.
Differential Revision:	https://reviews.freebsd.org/D19000
This commit is contained in:
rscheff 2020-04-29 21:48:52 +00:00
parent bb85a467ce
commit f8d5656acd
3 changed files with 31 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
sys/netinet/tcp_input.c
View File

@ -1470,7 +1470,7 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
struct tcpcb *tp, int drop_hdrlen, int tlen, uint8_t iptos)
{
int thflags, acked, ourfinisacked, needoutput = 0, sack_changed;
int rstreason, todrop, win;
int rstreason, todrop, win, incforsyn = 0;
uint32_t tiwin;
uint16_t nsegs;
char *s;
@ -2374,12 +2374,6 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
if (IS_FASTOPEN(tp->t_flags) && tp->t_tfo_pending) {
tcp_fastopen_decrement_counter(tp->t_tfo_pending);
tp->t_tfo_pending = NULL;
/*
* Account for the ACK of our SYN prior to
* regular ACK processing below.
*/
tp->snd_una++;
}
if (tp->t_flags & TF_NEEDFIN) {
tcp_state_change(tp, TCPS_FIN_WAIT_1);
@ -2399,6 +2393,13 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
cc_conn_init(tp);
tcp_timer_activate(tp, TT_KEEP, TP_KEEPIDLE(tp));
}
/*
* Account for the ACK of our SYN prior to
* regular ACK processing below, except for
* simultaneous SYN, which is handled later.
*/
if (SEQ_GT(th->th_ack, tp->snd_una) && !(tp->t_flags & TF_NEEDSYN))
incforsyn = 1;
/*
* If segment contains data or ACK, will call tcp_reass()
* later; if not, do so now to pass queued data to user.
@ -2693,6 +2694,15 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
process_ACK:
INP_WLOCK_ASSERT(tp->t_inpcb);
/*
* Adjust for the SYN bit in sequence space,
* but don't account for it in cwnd calculations.
* This is for the SYN_RECEIVED, non-simultaneous
* SYN case. SYN_SENT and simultaneous SYN are
* treated elsewhere.
*/
if (incforsyn)
tp->snd_una++;
acked = BYTES_THIS_ACK(tp, th);
KASSERT(acked >= 0, ("%s: acked unexepectedly negative "
"(tp->snd_una=%u, th->th_ack=%u, tp=%p, m=%p)", __func__,

12
sys/netinet/tcp_stacks/bbr.c
View File

@ -9326,11 +9326,6 @@ bbr_do_syn_recv(struct mbuf *m, struct tcphdr *th, struct socket *so,
tcp_fastopen_decrement_counter(tp->t_tfo_pending);
tp->t_tfo_pending = NULL;
/*
* Account for the ACK of our SYN prior to regular
* ACK processing below.
*/
tp->snd_una++;
}
/*
* Make transitions: SYN-RECEIVED -> ESTABLISHED SYN-RECEIVED* ->
@ -9353,6 +9348,13 @@ bbr_do_syn_recv(struct mbuf *m, struct tcphdr *th, struct socket *so,
if (!IS_FASTOPEN(tp->t_flags))
cc_conn_init(tp);
}
/*
* Account for the ACK of our SYN prior to
* regular ACK processing below, except for
* simultaneous SYN, which is handled later.
*/
if (SEQ_GT(th->th_ack, tp->snd_una) && !(tp->t_flags & TF_NEEDSYN))
tp->snd_una++;
/*
* If segment contains data or ACK, will call tcp_reass() later; if
* not, do so now to pass queued data to user.

13
sys/netinet/tcp_stacks/rack.c
View File

@ -6540,12 +6540,6 @@ rack_do_syn_recv(struct mbuf *m, struct tcphdr *th, struct socket *so,
if (IS_FASTOPEN(tp->t_flags) && tp->t_tfo_pending) {
tcp_fastopen_decrement_counter(tp->t_tfo_pending);
tp->t_tfo_pending = NULL;
/*
* Account for the ACK of our SYN prior to
* regular ACK processing below.
*/
tp->snd_una++;
}
if (tp->t_flags & TF_NEEDFIN) {
tcp_state_change(tp, TCPS_FIN_WAIT_1);
@ -6563,6 +6557,13 @@ rack_do_syn_recv(struct mbuf *m, struct tcphdr *th, struct socket *so,
if (!IS_FASTOPEN(tp->t_flags))
cc_conn_init(tp);
}
/*
* Account for the ACK of our SYN prior to
* regular ACK processing below, except for
* simultaneous SYN, which is handled later.
*/
if (SEQ_GT(th->th_ack, tp->snd_una) && !(tp->t_flags & TF_NEEDSYN))
tp->snd_una++;
/*
* If segment contains data or ACK, will call tcp_reass() later; if
* not, do so now to pass queued data to user.