netdev - RE: sctp: num_ostreams and max

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Message-ID: <9a1bfa6085854387bf98b6171c879b37@AcuMS.aculab.com>
Date:   Fri, 14 Aug 2020 13:36:34 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     "linux-sctp@...r.kernel.org" <linux-sctp@...r.kernel.org>,
        Neil Horman <nhorman@...driver.com>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: RE: sctp: num_ostreams and max_instreams negotiation

> > At some point the negotiation of the number of SCTP streams
> > seems to have got broken.
> > I've definitely tested it in the past (probably 10 years ago!)
> > but on a 5.8.0 kernel getsockopt(SCTP_INFO) seems to be
> > returning the 'num_ostreams' set by setsockopt(SCTP_INIT)
> > rather than the smaller of that value and that configured
> > at the other end of the connection.
> >
> > I'll do a bit of digging.
> 
> I can't find the code that processes the init_ack.
> But when sctp_procss_int() saves the smaller value
> in asoc->c.sinint_max_ostreams.
> 
> But afe899962ee079 (if I've typed it right) changed
> the values SCTP_INFO reported.
> Apparantly adding 'sctp reconfig' had changed things.
> 
> So I suspect this has all been broken for over 3 years.

It looks like the changes that broke it went into 4.11.
I've just checked a 3.8 kernel and that negotiates the
values down in both directions.

I don't have any kernels lurking between 3.8 and 4.15.
(Yes, I could build one, but it doesn't really help.)

	David

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