netdev - Re: [bpf PATCH v4 1/4] bpf: tls, implement unhash to avoid transition out of ESTABLISHED

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Date:   Tue, 14 May 2019 15:34:55 -0700
From:   John Fastabend <john.fastabend@...il.com>
To:     John Fastabend <john.fastabend@...il.com>,
        Jakub Kicinski <jakub.kicinski@...ronome.com>,
        John Fastabend <john.fastabend@...il.com>
Cc:     ast@...nel.org, daniel@...earbox.net, netdev@...r.kernel.org,
        bpf@...r.kernel.org, Eric Dumazet <edumazet@...gle.com>
Subject: Re: [bpf PATCH v4 1/4] bpf: tls, implement unhash to avoid transition
 out of ESTABLISHED

John Fastabend wrote:
> Jakub Kicinski wrote:
> > On Thu, 09 May 2019 21:57:49 -0700, John Fastabend wrote:
> > > @@ -2042,12 +2060,14 @@ void tls_sw_free_resources_tx(struct sock *sk)
> > >  	if (atomic_read(&ctx->encrypt_pending))
> > >  		crypto_wait_req(-EINPROGRESS, &ctx->async_wait);
> > >  
> > > -	release_sock(sk);
> > > +	if (locked)
> > > +		release_sock(sk);
> > >  	cancel_delayed_work_sync(&ctx->tx_work.work);
> > 
> > So in the splat I got (on a slightly hacked up kernel) it seemed like
> > unhash may be called in atomic context:
> > 
> > [  783.232150]  tls_sk_proto_unhash+0x72/0x110 [tls]
> > [  783.237497]  tcp_set_state+0x484/0x640
> > [  783.241776]  ? __sk_mem_reduce_allocated+0x72/0x4a0
> > [  783.247317]  ? tcp_recv_timestamp+0x5c0/0x5c0
> > [  783.252265]  ? tcp_write_queue_purge+0xa6a/0x1180
> > [  783.257614]  tcp_done+0xac/0x260
> > [  783.261309]  tcp_reset+0xbe/0x350
> > [  783.265101]  tcp_validate_incoming+0xd9d/0x1530
> > 
> > I may have been unclear off-list, I only tested the patch no longer
> > crashes the offload :(
> > 
> 
> Yep, I misread and thought it was resolved here as well. OK I'll dig into
> it. I'm not seeing it from selftests but I guess that means we are missing
> a testcase. :( yet another version I guess.
> 

Seems we need to call release_sock in the unhash case as well. Will
send a new patch shortly.

.John

> Thanks,
> John
>