Subject: Re: [PATCH] sctp: fix the fast retransmit limit

From: Vladislav Yasevich <[email-masked]>
Date: Thu, 03 Mar 2011 09:16:51 -0500

On 03/03/2011 04:29 AM, Wei Yongjun wrote:
> If chunk is still lost after fast retransmit, SCTP stack will
> never allow the second fast retransmit of this chunk, even if
> the peer need we do this. This chunk will be retransmit until
> the rtx timeout. This limit is introduce by the following patch:
>   sctp: reduce memory footprint of sctp_chunk structure
>   (c226ef9b83694311327f3ab0036c6de9c22e9daf)
> 
> This patch revert this limit and removed useless SCTP_DONT_FRTX.

NACK.  Please read the spec and how fast recovery is specified.

-vlad

> 
> Signed-off-by: Wei Yongjun <[email-masked]>
> ---
>  include/net/sctp/structs.h |    1 -
>  net/sctp/outqueue.c        |    4 ++--
>  2 files changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
> index cc9185c..82a0f84 100644
> --- a/include/net/sctp/structs.h
> +++ b/include/net/sctp/structs.h
> @@ -751,7 +751,6 @@ struct sctp_chunk {
>  
>  #define SCTP_CAN_FRTX 0x0
>  #define SCTP_NEED_FRTX 0x1
> -#define SCTP_DONT_FRTX 0x2
>  	__u16	rtt_in_progress:1,	/* This chunk used for RTT calc? */
>  		has_tsn:1,		/* Does this chunk have a TSN yet? */
>  		has_ssn:1,		/* Does this chunk have a SSN yet? */
> diff --git a/net/sctp/outqueue.c b/net/sctp/outqueue.c
> index 8c6d379..7ed5862 100644
> --- a/net/sctp/outqueue.c
> +++ b/net/sctp/outqueue.c
> @@ -657,7 +657,7 @@ redo:
>  			 * after it is retransmitted.
>  			 */
>  			if (chunk->fast_retransmit == SCTP_NEED_FRTX)
> -				chunk->fast_retransmit = SCTP_DONT_FRTX;
> +				chunk->fast_retransmit = SCTP_CAN_FRTX;
>  
>  			q->empty = 0;
>  			break;
> @@ -679,7 +679,7 @@ redo:
>  	if (rtx_timeout || fast_rtx) {
>  		list_for_each_entry(chunk1, lqueue, transmitted_list) {
>  			if (chunk1->fast_retransmit == SCTP_NEED_FRTX)
> -				chunk1->fast_retransmit = SCTP_DONT_FRTX;
> +				chunk1->fast_retransmit = SCTP_CAN_FRTX;
>  		}
>  	}
>