Vlad Yasevich wrote:
> Commit faee47cdbfe8d74a1573c2f81ea6dbb08d735be6
> (sctp: Fix the RTO-doubling on idle-link heartbeats)
> broke the RTO doubling for data retransmits. If the
> heartbeat was sent before the data T3-rtx time, the
> the RTO will not double upon the T3-rtx expiration.
> Distingish between the operations by passing an argument
> to the function.
>
Hi Vlad
I think we should talk about what the SCTP_CMD_TRANSPORT_RESET and
SCTP_CMD_HB_TIMER_UPDATE command do.
SCTP_CMD_TRANSPORT_RESET
--> sctp_cmd_transport_reset()
--> sctp_transport_lower_cwnd()
... transport->cwnd = XXX if timer expire
... partial_bytes_acked = 0;
--> sctp_do_8_2_transport_strike()
... asoc->overall_error_count++;
... transport->rto = XXX if not send HB
SCTP_CMD_HB_TIMER_UPDATE
--> sctp_cmd_hb_timer_update()
... mod_timer(&t->hb_timer, sctp_transport_timeout(t))
In sctp_sf_do_prm_requestheartbeat(), it used
SCTP_CMD_TRANSPORT_RESET command, not SCTP_CMD_HB_TIMER_UPDATE,
so if user request to send HB, the partial_bytes_acked will be clear,
and the overall_error_count be increased. And the heartbeat primitive
may not send HB, but only mark the transport state to SCTP_INACTIVE.
We user request to send HB immediately:
- the HB timer will be update, so HB will expires after
(HB_INTERVAL + RTO +/- 50% * RTO).
- the overall_error_count should not be increased. Because this is not
a idle-link heartbeat.
- the cwnd and partial_bytes_acked should not be changed.
Is this correct?
And after the patch I sent, used SCTP_CMD_HB_TIMER_UPDATE instead of
SCTP_CMD_TRANSPORT_RESET command. The action of idle-link heartbeat
and user initiated heartbeat are like this.
idle-link heartbeat:
Endpoint A Endpoint B
|
| idle
|
HEARTBEAT ----------->
| lower cwnd
| overall_error_count++
| RTO = RTO * 2
| expires HB_INTERVAL + RTO +/- 50% * RTO
HEARTBEAT ----------->
| lower cwnd
| overall_error_count++
| RTO = RTO * 2
| expires HB_INTERVAL + RTO +/- 50% * RTO
user initiated heartbeat
Endpoint A Endpoint B
|
|
|
HEARTBEAT -----------> (*) first HB
|
| reset hb_timer, not update RTO
|
HEARTBEAT ----------->
| lower cwnd
| overall_error_count++
| RTO = RTO * 2
| expires HB_INTERVAL + RTO +/- 50% * RTO
The different between two is that only reset the HB timer, the
other increased overall_error_count and lower cwnd. I agree with
reset the HB timer.
Regards.
> Signed-off-by: Vlad Yasevich <vladislav.yasevich@xxxxxx>
> ---
> net/sctp/sm_sideeffect.c | 10 ++++++----
> 1 files changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/net/sctp/sm_sideeffect.c b/net/sctp/sm_sideeffect.c
> index 0146cfb..4ac6163 100644
> --- a/net/sctp/sm_sideeffect.c
> +++ b/net/sctp/sm_sideeffect.c
> @@ -434,7 +434,8 @@ sctp_timer_event_t *sctp_timer_events[SCTP_NUM_TIMEOUT_TYPES] = {
> *
> */
> static void sctp_do_8_2_transport_strike(struct sctp_association *asoc,
> - struct sctp_transport *transport)
> + struct sctp_transport *transport,
> + int is_hb)
> {
> /* The check for association's overall error counter exceeding the
> * threshold is done in the state function.
> @@ -466,7 +467,7 @@ static void sctp_do_8_2_transport_strike(struct sctp_association *asoc,
> * The first unacknowleged HB triggers it. We do this with a flag
> * that indicates that we have an outstanding HB.
> */
> - if (transport->hb_sent) {
> + if (!is_hb || transport->hb_sent) {
> transport->last_rto = transport->rto;
> transport->rto = min((transport->rto * 2), transport->asoc->rto_max);
> }
> @@ -667,7 +668,7 @@ static void sctp_cmd_transport_reset(sctp_cmd_seq_t *cmds,
> sctp_transport_lower_cwnd(t, SCTP_LOWER_CWND_INACTIVE);
>
> /* Mark one strike against a transport. */
> - sctp_do_8_2_transport_strike(asoc, t);
> + sctp_do_8_2_transport_strike(asoc, t, 1);
>
> t->hb_sent = 1;
> }
> @@ -1459,7 +1460,8 @@ static int sctp_cmd_interpreter(sctp_event_t event_type,
>
> case SCTP_CMD_STRIKE:
> /* Mark one strike against a transport. */
> - sctp_do_8_2_transport_strike(asoc, cmd->obj.transport);
> + sctp_do_8_2_transport_strike(asoc, cmd->obj.transport,
> + 0);
> break;
>
> case SCTP_CMD_TRANSPORT_RESET:
>
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