[MPTCP] Re: [RFC 7/7] make accept not allocate kernel socket struct

[Florian Westphal <fw at strlen.de>]

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Paolo Abeni <pabeni(a)redhat.com> wrote:
> > No, its also for outgoing connections, we use in kernel sockets for
> > those.
> 
> Uhm...  I see. Everything created via mptcp_subflow_create_socket(),
> right? I though of always using msk's socket also/mainly to reduce the
> memory usage, but server side we should have very few
> mptcp_subflow_create_socket() instances, so I guess it's no necessary
> optimize them.

FWIW it might make sense to not have those in kernel sockets either
in the future, but this might need a bit more changes to how outgoing
connections work in mptcp-next.

I would have a look at it at some later date, I don't think its
a high priority.

> > > > @@ -1443,6 +1470,20 @@ static int mptcp_stream_accept(struct socket *sock, struct socket *newsock,
> > > >  		return -EINVAL;
> > > >  
> > > >  	err = ssock->ops->accept(sock, newsock, flags, kern);
> > > > +	if (err == 0 && (newsock->sk->sk_prot == &mptcp_prot ||
> > > > +			 is_mptcp_v6(newsock))) {
> > > 
> > > Is not clear to me why/how we can hit the condition '!(newsock->sk-
> > > > sk_prot == &mptcp_prot || is_mptcp_v6(newsock))' ... Can you please
> > > explain?
> > 
> > We will hit it when we get connection from non-mptcp peer, i.e. the
> > !mp_capable part of mptcp_accept().
> > 
> > In that case sk_prot is &tcp_prot.
> > 
> > It might make sense to change this to
> >     err == 0 && newsock->sk->sk_prot != &tcp_prot
> > 
> > perhaps that would clarify this a bit.  WDYT?
> 
> Yep, I like this latter code more!

Ok, I've flagged the patches 'RFC' in patchwork already.
I will make this change and will resubmit that part later.

Thanks,
Florian