[CCID 3]: Fix packet tardiness BUG
This fixes a bug introduced by myself.
A huge lot of thanks to Ian McDonald who identified this bug.
Problem:
--------
Due to packet scheduling in CCID 3, it can happen that the
actual send time of a packet is later than t_now: in this case
t_nom < t_now.
This case brings the entire packet scheduling out of sync, since
the next packet is scheduled at t_nom + t_ipi, and t_nom is in
the past.
Fix:
----
Update t_nom to t_now whenever a packet is late due to scheduling
(and then t_nom < t_now). This update takes place in ccid3_hc_tx_
send_packet. In between calls to this function, it is irrelevant
if t_nom < t_now (since it will be caught eventually).
Signed-off-by: Gerrit Renker <gerrit@xxxxxxxxxxxxxx>
---
net/dccp/ccids/ccid3.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
--- a/net/dccp/ccids/ccid3.c
+++ b/net/dccp/ccids/ccid3.c
@@ -349,7 +349,9 @@ static int ccid3_hc_tx_send_packet(struc
case TFRC_SSTATE_NO_FBACK:
case TFRC_SSTATE_FBACK:
delay = timeval_delta(&hctx->ccid3hctx_t_nom, &now);
- ccid3_pr_debug("delay=%ld\n", (long)delay);
+ /* handle packet tardiness: synchronise t_nom with send time */
+ if (delay < 0)
+ hctx->ccid3hctx_t_nom = now;
/*
* Scheduling of packet transmissions [RFC 3448, 4.6]
*
@@ -358,7 +360,7 @@ static int ccid3_hc_tx_send_packet(struc
* else
* // send the packet in (t_nom - t_now) milliseconds.
*/
- if (delay - (suseconds_t)hctx->ccid3hctx_delta >= 0)
+ else if (delay - (suseconds_t)hctx->ccid3hctx_delta >= 0)
return delay / 1000L;
ccid3_hc_tx_update_win_count(hctx, &now);
-
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