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SubjectRe: [PATCH] net: sctp: recover a tranport when an ack comes

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.

static void sctp_check_transmitted(...) {
...
if (transport) { /*<=======This proves that its not the
outq->retransmit (the retransmitted queue)*/
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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