The branch stable/13 has been updated by rscheff:
URL:
https://cgit.FreeBSD.org/src/commit/?id=ab9104cbe4d53ee337a7281151540e32bfcb8d25
commit ab9104cbe4d53ee337a7281151540e32bfcb8d25
Author: Richard Scheffenegger <rsch...@freebsd.org>
AuthorDate: 2021-04-20 12:53:56 +0000
Commit: Richard Scheffenegger <rsch...@freebsd.org>
CommitDate: 2021-04-23 07:26:18 +0000
tcp: Deal with DSACKs, and adjust rescue hole on success.
When a rescue retransmission is successful, rather than
inserting new holes to the left of it, adjust the old
rescue entry to cover the missed sequence space.
Also, as snd_fack may be stale by that point, pull it forward
in order to never create a hole left of snd_una/th_ack.
Finally, with DSACKs, tcp_sack_doack() may be called
with new full ACKs but a DSACK block. Account for this
eventuality properly to keep sacked_bytes >= 0.
MFC after: 3 days
Reviewed By: kbowling, tuexen, #transport
Sponsored by: NetApp, Inc.
Differential Revision: https://reviews.freebsd.org/D29835
(cherry picked from commit a649f1f6fd7a098ab173a69fe87916c04a8c6f8d)
---
sys/netinet/tcp_sack.c | 76 +++++++++++++++++++++++++++++++-------------------
1 file changed, 47 insertions(+), 29 deletions(-)
diff --git a/sys/netinet/tcp_sack.c b/sys/netinet/tcp_sack.c
index 08ce2a0882b1..40d63bd3832f 100644
--- a/sys/netinet/tcp_sack.c
+++ b/sys/netinet/tcp_sack.c
@@ -491,7 +491,7 @@ static struct sackhole *
tcp_sackhole_insert(struct tcpcb *tp, tcp_seq start, tcp_seq end,
struct sackhole *after)
{
- struct sackhole *hole, *tail;
+ struct sackhole *hole;
/* Allocate a new SACK hole. */
hole = tcp_sackhole_alloc(tp, start, end);
@@ -502,15 +502,7 @@ tcp_sackhole_insert(struct tcpcb *tp, tcp_seq start,
tcp_seq end,
if (after != NULL)
TAILQ_INSERT_AFTER(&tp->snd_holes, after, hole, scblink);
else
- /*
- * With Rescue Retransmission, new holes may need to
- * be inserted just before the tail.
- */
- if (((tail = TAILQ_LAST_FAST(&tp->snd_holes, sackhole,
- scblink)) != NULL) && SEQ_LEQ(end, tail->start))
- TAILQ_INSERT_BEFORE(tail, hole, scblink);
- else
- TAILQ_INSERT_TAIL(&tp->snd_holes, hole, scblink);
+ TAILQ_INSERT_TAIL(&tp->snd_holes, hole, scblink);
/* Update SACK hint. */
if (tp->sackhint.nexthole == NULL)
@@ -567,6 +559,15 @@ tcp_sack_doack(struct tcpcb *tp, struct tcpopt *to,
tcp_seq th_ack)
left_edge_delta = th_ack - tp->snd_una;
sack_blocks[num_sack_blks].start = tp->snd_una;
sack_blocks[num_sack_blks++].end = th_ack;
+ /*
+ * Pulling snd_fack forward if we got here
+ * due to DSACK blocks
+ */
+ if (SEQ_LT(tp->snd_fack, th_ack)) {
+ delivered_data += th_ack - tp->snd_una;
+ tp->snd_fack = th_ack;
+ sack_changed = 1;
+ }
}
/*
* Append received valid SACK blocks to sack_blocks[], but only if we
@@ -636,35 +637,52 @@ tcp_sack_doack(struct tcpcb *tp, struct tcpopt *to,
tcp_seq th_ack)
tp->sackhint.last_sack_ack = sblkp->end;
if (SEQ_LT(tp->snd_fack, sblkp->start)) {
/*
- * The highest SACK block is beyond fack. Append new SACK
- * hole at the tail. If the second or later highest SACK
- * blocks are also beyond the current fack, they will be
- * inserted by way of hole splitting in the while-loop below.
+ * The highest SACK block is beyond fack. First,
+ * check if there was a successful Rescue Retransmission,
+ * and move this hole left. With normal holes, snd_fack
+ * is always to the right of the end.
*/
- temp = tcp_sackhole_insert(tp, tp->snd_fack,sblkp->start,NULL);
- if (temp != NULL) {
+ if (((temp = TAILQ_LAST(&tp->snd_holes, sackhole_head)) !=
NULL) &&
+ SEQ_LEQ(tp->snd_fack,temp->end)) {
+ temp->start = SEQ_MAX(tp->snd_fack,
SEQ_MAX(tp->snd_una, th_ack));
+ temp->end = sblkp->start;
+ temp->rxmit = temp->start;
delivered_data += sblkp->end - sblkp->start;
tp->snd_fack = sblkp->end;
- /* Go to the previous sack block. */
sblkp--;
sack_changed = 1;
} else {
/*
- * We failed to add a new hole based on the current
- * sack block. Skip over all the sack blocks that
- * fall completely to the right of snd_fack and
- * proceed to trim the scoreboard based on the
- * remaining sack blocks. This also trims the
- * scoreboard for th_ack (which is sack_blocks[0]).
+ * Append a new SACK hole at the tail. If the
+ * second or later highest SACK blocks are also
+ * beyond the current fack, they will be inserted
+ * by way of hole splitting in the while-loop below.
*/
- while (sblkp >= sack_blocks &&
- SEQ_LT(tp->snd_fack, sblkp->start))
- sblkp--;
- if (sblkp >= sack_blocks &&
- SEQ_LT(tp->snd_fack, sblkp->end)) {
- delivered_data += sblkp->end - tp->snd_fack;
+ temp = tcp_sackhole_insert(tp,
tp->snd_fack,sblkp->start,NULL);
+ if (temp != NULL) {
+ delivered_data += sblkp->end - sblkp->start;
tp->snd_fack = sblkp->end;
+ /* Go to the previous sack block. */
+ sblkp--;
sack_changed = 1;
+ } else {
+ /*
+ * We failed to add a new hole based on the
current
+ * sack block. Skip over all the sack blocks
that
+ * fall completely to the right of snd_fack and
+ * proceed to trim the scoreboard based on the
+ * remaining sack blocks. This also trims the
+ * scoreboard for th_ack (which is
sack_blocks[0]).
+ */
+ while (sblkp >= sack_blocks &&
+ SEQ_LT(tp->snd_fack, sblkp->start))
+ sblkp--;
+ if (sblkp >= sack_blocks &&
+ SEQ_LT(tp->snd_fack, sblkp->end)) {
+ delivered_data += sblkp->end -
tp->snd_fack;
+ tp->snd_fack = sblkp->end;
+ sack_changed = 1;
+ }
}
}
} else if (SEQ_LT(tp->snd_fack, sblkp->end)) {
_______________________________________________
dev-commits-src-all@freebsd.org mailing list
https://lists.freebsd.org/mailman/listinfo/dev-commits-src-all
To unsubscribe, send any mail to "dev-commits-src-all-unsubscr...@freebsd.org"
