On 11/22/2013 03:30 AM, Xufeng Zhang wrote:
> From: Signed-off-by: Xufeng Zhang <xufeng.zhang@xxxxxxxxxxxxx>
>
> Currently retransmitted DATA chunks could also be used for
> RTT measurements since there are no flag to identify whether
> the transmitted DATA chunk is a new one or a retransmitted one.
> This problem is introduced by commit ae19c5486 ("sctp: remove
> 'resent' bit from the chunk") which inappropriately removed the
> 'resent' bit completely, instead of doing this, we should set
> the resent bit only for the retransmitted DATA chunks.
>
> Signed-off-by: Xufeng Zhang <xufeng.zhang@xxxxxxxxxxxxx>
> ---
> include/net/sctp/structs.h | 1 +
> net/sctp/output.c | 23 +++++++++++++----------
> net/sctp/outqueue.c | 3 +++
> net/sctp/sm_make_chunk.c | 1 +
> 4 files changed, 18 insertions(+), 10 deletions(-)
>
> diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
> index 2174d8d..ea0ca5f 100644
> --- a/include/net/sctp/structs.h
> +++ b/include/net/sctp/structs.h
> @@ -629,6 +629,7 @@ struct sctp_chunk {
> #define SCTP_NEED_FRTX 0x1
> #define SCTP_DONT_FRTX 0x2
> __u16 rtt_in_progress:1, /* This chunk used for RTT calc? */
> + resent:1, /* Has this chunk ever been resent. */
> has_tsn:1, /* Does this chunk have a TSN yet? */
> has_ssn:1, /* Does this chunk have a SSN yet? */
> singleton:1, /* Only chunk in the packet? */
> diff --git a/net/sctp/output.c b/net/sctp/output.c
> index e650978..32c214d 100644
> --- a/net/sctp/output.c
> +++ b/net/sctp/output.c
> @@ -467,17 +467,20 @@ int sctp_packet_transmit(struct sctp_packet *packet)
> list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) {
> list_del_init(&chunk->list);
> if (sctp_chunk_is_data(chunk)) {
> - /* 6.3.1 C4) When data is in flight and when allowed
> - * by rule C5, a new RTT measurement MUST be made each
> - * round trip. Furthermore, new RTT measurements
> - * SHOULD be made no more than once per round-trip
> - * for a given destination transport address.
> - */
> -
> - if (!tp->rto_pending) {
> - chunk->rtt_in_progress = 1;
> - tp->rto_pending = 1;
> + if (!chunk->resent) {
> + /* 6.3.1 C4) When data is in flight and when allowed
> + * by rule C5, a new RTT measurement MUST be made each
> + * round trip. Furthermore, new RTT measurements
> + * SHOULD be made no more than once per round-trip
> + * for a given destination transport address.
> + */
> +
> + if (!tp->rto_pending) {
Could be combined as
if (!chunk->resent && !tp->rto_pending) {
> + chunk->rtt_in_progress = 1;
> + tp->rto_pending = 1;
> + }
> }
> +
> has_data = 1;
> }
>
> diff --git a/net/sctp/outqueue.c b/net/sctp/outqueue.c
> index 94df758..70f4f56 100644
> --- a/net/sctp/outqueue.c
> +++ b/net/sctp/outqueue.c
> @@ -446,6 +446,8 @@ void sctp_retransmit_mark(struct sctp_outq *q,
> transport->rto_pending = 0;
> }
>
> + chunk->resent = 1;
> +
> /* Move the chunk to the retransmit queue. The chunks
> * on the retransmit queue are always kept in order.
> */
> @@ -1375,6 +1377,7 @@ static void sctp_check_transmitted(struct sctp_outq *q,
> * instance).
> */
> if (!tchunk->tsn_gap_acked &&
> + !tchunk->resent &&
> tchunk->rtt_in_progress) {
> tchunk->rtt_in_progress = 0;
> rtt = jiffies - tchunk->sent_at;
> diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c
> index fe69032..8fe89f8 100644
> --- a/net/sctp/sm_make_chunk.c
> +++ b/net/sctp/sm_make_chunk.c
> @@ -1321,6 +1321,7 @@ struct sctp_chunk *sctp_chunkify(struct sk_buff *skb,
> INIT_LIST_HEAD(&retval->list);
> retval->skb = skb;
> retval->asoc = (struct sctp_association *)asoc;
> + retval->resent = 0;
Not needed due to zeroed out malloc.
-vlad
> retval->singleton = 1;
>
> retval->fast_retransmit = SCTP_CAN_FRTX;
>
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