tcp: fix tail rescue with sacks
Type: fix
Change-Id: Iad73f47cef3d29c4b0b7d1f58f2f2b14ba4b1d38
Signed-off-by: Florin Coras <fcoras@cisco.com>
diff --git a/src/vnet/tcp/tcp_output.c b/src/vnet/tcp/tcp_output.c
index f63ffa6..05db727 100644
--- a/src/vnet/tcp/tcp_output.c
+++ b/src/vnet/tcp/tcp_output.c
@@ -1924,8 +1924,10 @@
u32 n_segs_new;
int av_wnd;
+ /* Make sure we don't exceed available window and leave space
+ * for one more packet, to avoid zero window acks */
av_wnd = (int) tc->snd_wnd - (tc->snd_nxt - tc->snd_una);
- av_wnd = clib_max (av_wnd, 0);
+ av_wnd = clib_max (av_wnd - tc->snd_mss, 0);
snd_space = clib_min (snd_space, av_wnd);
snd_space = clib_min (max_deq, snd_space);
burst_size = clib_min (burst_size - n_segs,
@@ -1948,16 +1950,16 @@
* unSACKed sequence number SHOULD be returned, and RescueRxt set to
* RecoveryPoint. HighRxt MUST NOT be updated.
*/
- max_bytes = clib_min (tc->snd_mss,
- tc->snd_congestion - tc->snd_una);
+ hole = scoreboard_last_hole (sb);
+ max_bytes = clib_min (tc->snd_mss, hole->end - hole->start);
max_bytes = clib_min (max_bytes, snd_space);
- offset = tc->snd_congestion - tc->snd_una - max_bytes;
- sb->rescue_rxt = tc->snd_congestion;
+ offset = hole->end - tc->snd_una - max_bytes;
n_written = tcp_prepare_retransmit_segment (wrk, tc, offset,
max_bytes, &b);
if (!n_written)
goto done;
+ sb->rescue_rxt = tc->snd_congestion;
bi = vlib_get_buffer_index (vm, b);
tcp_enqueue_to_output (wrk, b, bi, tc->c_is_ip4);
n_segs += 1;