Re: [PATCH net 3/5] sctp: only allow the asoc reset when the asoc outq is empty

[Marcelo Ricardo Leitner]

On Sat, Nov 25, 2017 at 09:05:34PM +0800, Xin Long wrote:
> As it says in rfc6525#section5.1.4, before sending the request,
> 
>C2:  The sender has either no outstanding TSNs or considers all
> outstanding TSNs abandoned.
> 
> Prior to this patch, it tried to consider all outstanding TSNs abandoned
> by dropping all chunks in all outqs with sctp_outq_free (even including
> sacked, retransmit and transmitted queues) when doing this reset, which
> is too aggressive.
> 
> To make it work gently, this patch will only allow the asoc reset when
> the sender has no outstanding TSNs by checking if unsent, transmitted
> and retransmit are all empty with sctp_outq_is_empty before sending
> and processing the request.
> 
> Fixes: 692787cef651 ("sctp: implement receiver-side procedures for the 
> SSN/TSN Reset Request Parameter")
> Signed-off-by: Xin Long 

Acked-by: Marcelo Ricardo Leitner 

> ---
>  net/sctp/stream.c | 9 +
>  1 file changed, 9 insertions(+)
> 
> diff --git a/net/sctp/stream.c b/net/sctp/stream.c
> index b209037..f3b7d27 100644
> --- a/net/sctp/stream.c
> +++ b/net/sctp/stream.c
> @@ -406,6 +406,9 @@ int sctp_send_reset_assoc(struct sctp_association *asoc)
>   if (asoc->strreset_outstanding)
>   return -EINPROGRESS;
>  
> + if (!sctp_outq_is_empty(>outqueue))
> + return -EAGAIN;
> +
>   chunk = sctp_make_strreset_tsnreq(asoc);
>   if (!chunk)
>   return -ENOMEM;
> @@ -728,6 +731,12 @@ struct sctp_chunk *sctp_process_strreset_tsnreq(
>   }
>   goto err;
>   }
> +
> + if (!sctp_outq_is_empty(>outqueue)) {
> + result = SCTP_STRRESET_IN_PROGRESS;
> + goto err;
> + }
> +
>   asoc->strreset_inseq++;
>  
>   if (!(asoc->strreset_enable & SCTP_ENABLE_RESET_ASSOC_REQ))
> -- 
> 2.1.0
> 
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Re: [PATCH net 3/5] sctp: only allow the asoc reset when the asoc outq is empty

[Xin Long]

On Mon, Nov 27, 2017 at 6:06 PM, David Laight  wrote:
> From: Xin Long
>> Sent: 25 November 2017 13:06
>>
>> As it says in rfc6525#section5.1.4, before sending the request,
>>
>>C2:  The sender has either no outstanding TSNs or considers all
>> outstanding TSNs abandoned.
>>
>> Prior to this patch, it tried to consider all outstanding TSNs abandoned
>> by dropping all chunks in all outqs with sctp_outq_free (even including
>> sacked, retransmit and transmitted queues) when doing this reset, which
>> is too aggressive.
>>
>> To make it work gently, this patch will only allow the asoc reset when
>> the sender has no outstanding TSNs by checking if unsent, transmitted
>> and retransmit are all empty with sctp_outq_is_empty before sending
>> and processing the request.
>
> Doesn't that rather defeat the point of a reset?
No, reset here means to reset the next tsn/ssn, not with the cost of
losing outstanding data, though RFC6525 allows to consider them
abandoned.

RE: [PATCH net 3/5] sctp: only allow the asoc reset when the asoc outq is empty

[David Laight]

From: Xin Long
> Sent: 25 November 2017 13:06
> 
> As it says in rfc6525#section5.1.4, before sending the request,
> 
>C2:  The sender has either no outstanding TSNs or considers all
> outstanding TSNs abandoned.
> 
> Prior to this patch, it tried to consider all outstanding TSNs abandoned
> by dropping all chunks in all outqs with sctp_outq_free (even including
> sacked, retransmit and transmitted queues) when doing this reset, which
> is too aggressive.
> 
> To make it work gently, this patch will only allow the asoc reset when
> the sender has no outstanding TSNs by checking if unsent, transmitted
> and retransmit are all empty with sctp_outq_is_empty before sending
> and processing the request.

Doesn't that rather defeat the point of a reset?

David