On 11/15/2013 05:04 PM, Chang wrote:
>
> On 11/15/2013 03:34 AM, Vlad Yasevich wrote:
>> I don't think this is right. The spec states:
>> 8. ACKs for retransmissions do not transition a PF destination back
>> to Active state, since a sender cannot disambiguate whether the
>> ack was for the original transmission or the retransmission(s).
>>
> Could you please reconsider my proposal?
>
> In the rule 8, it clearly specifies ACKs for *retransmission* do not
> transition ... But those chunks were not retransmitted!
>
> Every transport maintains its own [transport->transmitted] queue, when
> retransmit happens (no matter time_out or fast_retransmit). The chunk
> would be removed from the queue and moved to the sctp_outq->retransmit.
>
Yes, this is their temporary holding area. Once the chunks are
transmitted again, they are placed on the transports transmitted list.
See sctp_outq_flush_rtx().
> static void sctp_check_transmitted(...) {
> ...
> if (transport) { /*<=======This proves that its not the
> outq->retransmit (the retransmitted queue)*/
Retransmit queue may hold more data then can be drained in a single
push. Thus is usually holds data that is pending retransmission, but
is not retransmitted yet. If a late SACK arrives acknowledging this
data, we need to properly mark it. That is what this code tries
to do.
-vlad
> if (bytes_acked) {
> ...
> if((transport->state in [INACTIVE, UNCONFIRMED, PF]...)
> sctp_assoc_control_transport(..., SCTP_TRANSPORT_UP).
>
>
> In addition, if its not appropriate to transition PF->ACTIVE, why is it
> appropriate to transition INACTIVE->ACTIVE (the original implementation).
>>
>> Now, the proper way to this would would be modify
>> sctp_assoc_control_transport() to transition the transport state to
>> ACTIVE if it was PF transport that was chosen to send data.
>>
>> -vlad
>>
>>> ---
>>> net/sctp/outqueue.c | 1 +
>>> 1 file changed, 1 insertion(+)
>>>
>>> diff --git a/net/sctp/outqueue.c b/net/sctp/outqueue.c
>>> index 94df758..2557fa5 100644
>>> --- a/net/sctp/outqueue.c
>>> +++ b/net/sctp/outqueue.c
>>> @@ -1517,6 +1517,7 @@ static void sctp_check_transmitted(struct
>>> sctp_outq *q,
>>> * active if it is not so marked.
>>> */
>>> if ((transport->state == SCTP_INACTIVE ||
>>> + transport->state == SCTP_PF ||
>>> transport->state == SCTP_UNCONFIRMED) &&
>>> sctp_cmp_addr_exact(&transport->ipaddr, saddr)) {
>>> sctp_assoc_control_transport(
>>>
>>
>
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