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

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Date:   Fri, 10 May 2019 16:03:14 -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,
        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

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.

Thanks,
John


> > -	lock_sock(sk);
> > +	if (locked)
> > +		lock_sock(sk);
> >  
> >  	/* Tx whatever records we can transmit and abandon the rest */
> > -	tls_tx_records(sk, -1);
> > +	tls_tx_records(sk, tls_ctx, -1);
> >  
> >  	/* Free up un-sent records in tx_list. First, free
> >  	 * the partially sent record if any at head of tx_list.
>