linux-kernel - Re: SCTP_PEER_ADDR_CHANGE Notification over UNCONFIRMED path

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Message-ID: <53EDD3B9.9070301@gmail.com>
Date:	Fri, 15 Aug 2014 17:32:41 +0800
From:	zhuyj <zyjzyj2000@...il.com>
To:	LKML <linux-kernel@...r.kernel.org>,
	netdev <netdev@...r.kernel.org>,
	Vlad Yasevich <vyasevich@...il.com>, tuexen@...muenster.de,
	khandelwal.deepak.1987@...il.com,
	"Tao, Yue" <Yue.Tao@...driver.com>,
	Alexandre Dietsch <alexandre.dietsch@...driver.com>,
	"David S. Miller" <davem@...emloft.net>,
	zhuyj <zyjzyj2000@...il.com>
Subject: Re: SCTP_PEER_ADDR_CHANGE Notification over UNCONFIRMED path

Sorry. I used attachment to send patch. Maybe it is not convenient. Now 
I resend it again. Please ignore this mail.

Best Regards!
Zhu Yanjun
On 08/15/2014 04:49 PM, zhuyj wrote:
> Hi, Vlad && DEEPAK && Michael && David
>
> From Michael && DEEPAK
> "
>  lxr SCTP implementation, doesn't transit the path state to INACTIVE, 
> if it was never confirmed. this leads to SCTP_PEER_ADDRESS_CHANGE 
> notification after each failed probe from this time.
>  Is there any specific reason to have same notification to SCTP User 
> with each probe in RTO time period ?
>  806 case SCTP_TRANSPORT_DOWN:
>  807 /* If the transport was never confirmed, do not transition it
>  808 * to inactive state. Also, release the cached route since
>  809 * there may be a better route next time.
>  810 */
>  811 if (transport->state != SCTP_UNCONFIRMED)
>
>  812 transport->state = SCTP_INACTIVE;
>
>  http://lxr.free-electrons.com/source/net/sctp/associola.c#L806
>
>  we checked RFC and here it is mentioned as  Path Verification 
> Section(5.4) of RFC 4960  http://tools.ietf.org/html/rfc4960
>
>  In each RTO, a probe may be sent on an active UNCONFIRMED path in an
>  attempt to move it to the CONFIRMED state. If during this probing
>  the path becomes inactive, this rate is lowered to the normal
>  HEARTBEAT rate. At the expiration of the RTO timer, the error
>  counter of any path that was probed but not CONFIRMED is incremented
>  by one and subjected to path failure detection, as defined in
>  Section
>
>
>  8.2
>  . When probing UNCONFIRMED addresses, however, the association
>  overall error counter is not incremented
>
>
>  Does this mean that in attempt to move a UNCONFIRMED path to 
> CONFIRMED State, the path can become INACTIVE, when transport error 
> counter reaches to path_max_retrans counter ?
>  I would say that the path stays UNCONFIRMED.
>
>
>  I would also only expect a  SCTP_PEER_ADDRESS_CHANGE notification 
> when a path state changes, not on every  try.
>
> "
>
> I made a patch to disable sending SCTP_PEER_ADDRESS_CHANGE 
> notification every try. Now the patch is in the attachment. Please 
> check it.
>
> Zhu Yanjun

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