netdev - Re: [bpf PATCH v2 2/6] bpf: tls fix transition through disconnect with close

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Date:   Thu, 11 Jul 2019 14:25:54 -0700
From:   John Fastabend <john.fastabend@...il.com>
To:     Jakub Kicinski <jakub.kicinski@...ronome.com>,
        John Fastabend <john.fastabend@...il.com>
Cc:     ast@...nel.org, daniel@...earbox.net, netdev@...r.kernel.org,
        edumazet@...gle.com, bpf@...r.kernel.org
Subject: Re: [bpf PATCH v2 2/6] bpf: tls fix transition through disconnect
 with close

Jakub Kicinski wrote:
> On Thu, 11 Jul 2019 09:47:16 -0700, John Fastabend wrote:
> > Jakub Kicinski wrote:
> > > On Wed, 10 Jul 2019 12:34:17 -0700, Jakub Kicinski wrote:  
> > > > > > > +		if (sk->sk_prot->unhash)
> > > > > > > +			sk->sk_prot->unhash(sk);
> > > > > > > +	}
> > > > > > > +
> > > > > > > +	ctx = tls_get_ctx(sk);
> > > > > > > +	if (ctx->tx_conf == TLS_SW || ctx->rx_conf == TLS_SW)
> > > > > > > +		tls_sk_proto_cleanup(sk, ctx, timeo);  
> > > 
> > > Do we still need to hook into unhash? With patch 6 in place perhaps we
> > > can just do disconnect 🥺  
> > 
> > ?? "can just do a disconnect", not sure I folow. We still need unhash
> > in cases where we have a TLS socket transition from ESTABLISHED
> > to LISTEN state without calling close(). This is independent of if
> > sockmap is running or not.
> > 
> > Originally, I thought this would be extremely rare but I did see it
> > in real applications on the sockmap side so presumably it is possible
> > here as well.
> 
> Ugh, sorry, I meant shutdown. Instead of replacing the unhash callback
> replace the shutdown callback. We probably shouldn't release the socket
> lock either there, but we can sleep, so I'll be able to run the device
> connection remove callback (which sleep).
> 

ah OK seems doable to me. Do you want to write that on top of this
series? Or would you like to push it onto your branch and I can pull
it in push the rest of the patches on top and send it out? I think
if you can get to it in the next few days then it makes sense to wait.

I can't test the hardware side so probably makes more sense for
you to do it if you can.


> > > cleanup is going to kick off TX but also:
> > > 
> > > 	if (unlikely(sk->sk_write_pending) &&
> > > 	    !wait_on_pending_writer(sk, &timeo))
> > > 		tls_handle_open_record(sk, 0);
> > > 
> > > Are we guaranteed that sk_write_pending is 0?  Otherwise
> > > wait_on_pending_writer is hiding yet another release_sock() :(  
> > 
> > Not seeing the path to release_sock() at the moment?
> > 
> >    tls_handle_open_record
> >      push_pending_record
> >       tls_sw_push_pending_record
> >         bpf_exec_tx_verdict
> 
> wait_on_pending_writer
>   sk_wait_event
>     release_sock
> 

ah OK. I'll check on sk_write_pending...

> > If bpf_exec_tx_verdict does a redirect we could hit a relase but that
> > is another fix I have to get queued up shortly. I think we can fix
> > that in another series.
> 
> Ugh.