ktls: Fix error/mode confusion in TCP_*TLS_MODE getsockopt handlers

[markj]

Summary

ktls_get_(rx|tx)_mode() can return an errno value or a TLS mode, so
errors are effectively hidden. Fix this. Convert to the new socket
buffer locking macros while here.

Note that the socket buffer lock is not needed to synchronize the
SOLISTENING check here, we can rely on the PCB lock, acquired in
tcp_usr_listen().

[jhb]

I think this is fine, just one thought.

sys/netinet/tcp_usrreq.c

2566

Did you consider doing the SOLISTENING check here instead of in the ktls_get_*_mode() routines?

[markj]

sys/netinet/tcp_usrreq.c

2566

Hmm, not really. I noticed that other ktls_* routines check for listening sockets and the TCP socket option (wow there's a lot of them...) handlers generally do not, so it made sense to me to keep things consistent.

[jhb]

sys/netinet/tcp_usrreq.c

2566

Ok. Either way is fine with me.