netdev - Re: [bpf PATCH v2 1/3] bpf: tls, implement unhash to avoid transition out of ESTABLISHED

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Date:   Thu, 25 Apr 2019 12:32:20 -0700
From:   John Fastabend <john.fastabend@...il.com>
To:     Jakub Kicinski <jakub.kicinski@...ronome.com>
Cc:     ast@...nel.org, daniel@...earbox.net, netdev@...r.kernel.org,
        bpf@...r.kernel.org
Subject: Re: [bpf PATCH v2 1/3] bpf: tls, implement unhash to avoid transition
 out of ESTABLISHED

On 4/25/19 12:29 PM, Jakub Kicinski wrote:
> On Thu, 25 Apr 2019 09:03:08 -0700, John Fastabend wrote:
>> +static void tls_sk_proto_unhash(struct sock *sk)
>> +{
>> +	struct tls_context *ctx = tls_get_ctx(sk);
>> +	void (*sk_proto_unhash)(struct sock *sk);
>> +	bool free_ctx;
>> +
>> +	if (!ctx)
>> +		return sk->sk_prot->unhash(sk);
>> +	sk_proto_unhash = ctx->sk_proto_unhash;
>> +	free_ctx = tls_sk_proto_destroy(sk, ctx, false);
>> +	tls_put_ctx(sk);
> 
> Oh, I think you can't put_ctx() unconditionally,
> when free_ctx is false, tls_device_sk_destruct() 
> needs it the ctx pointer.
> 
> I think this explains the offload crashing.
> 

ugh yeah. So we need to _not_ free it from tls_sk_proto_destroy
do the put_ctx and then finally free it. Otherwise we can't
restore the sk_proto fields. v3 on its way. Thanks.

>> +	if (sk_proto_unhash)
>> +		sk_proto_unhash(sk);
>> +	if (free_ctx)
>> +		tls_ctx_free(ctx);
>> +}
>>  
>> -skip_tx_cleanup:
>> +static void tls_sk_proto_close(struct sock *sk, long timeout)
>> +{
>> +	void (*sk_proto_close)(struct sock *sk, long timeout);
>> +	struct tls_context *ctx = tls_get_ctx(sk);
>> +	bool free_ctx;
>> +
>> +	if (!ctx)
>> +		return sk->sk_prot->destroy(sk);
>> +
>> +	lock_sock(sk);
>> +	sk_proto_close = ctx->sk_proto_close;
>> +	free_ctx = tls_sk_proto_destroy(sk, ctx, true);
>> +	tls_put_ctx(sk);