From: Eric Dumazet <[email protected]>
Date: Fri, 26 May 2017 07:16:59 -0700
> On Wed, 2017-05-24 at 09:27 -0700, Dave Watson wrote:
>> Software implementation of transport layer security, implemented using ULP
>> infrastructure. tcp proto_ops are replaced with tls equivalents of sendmsg
>> and
>> sendpage.
>
> ...
>
>> +
>> +int tls_sw_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
>> +{
> ...
>> +
>> + lock_sock(sk);
>> +
>> + /* Only one writer at a time is allowed */
>> + if (sk->sk_write_pending)
>> + return -EBUSY;
>
> Ouch...
Well, as I understand it, it is the same restriction userspace must
itself enforce either in the application or in the SSL library.