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

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Date:   Mon, 27 Nov 2017 18:58:11 +0800
From:   Xin Long <lucien.xin@...il.com>
To:     David Laight <David.Laight@...lab.com>
Cc:     network dev <netdev@...r.kernel.org>,
        "linux-sctp@...r.kernel.org" <linux-sctp@...r.kernel.org>,
        "davem@...emloft.net" <davem@...emloft.net>,
        Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
        Neil Horman <nhorman@...driver.com>
Subject: Re: [PATCH net 3/5] sctp: only allow the asoc reset when the asoc
 outq is empty

On Mon, Nov 27, 2017 at 6:06 PM, David Laight <David.Laight@...lab.com> 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.