SOCKET_URING_OP_GETSOCKOPT SOL_SOCKET restriction

[Stefan Metzmacher <metze@samba.org>]

Hi Jens,

while playing with the kernel QUIC driver [1],
I noticed it does a lot of getsockopt() and setsockopt()
calls to sync the required state into and out of the kernel.

My long term plan is to let the userspace quic handshake logic
work with SOCKET_URING_OP_GETSOCKOPT and SOCKET_URING_OP_SETSOCKOPT.

The used level is SOL_QUIC and that won't work
as io_uring_cmd_getsockopt() has a restriction to
SOL_SOCKET, while there's no restriction in
io_uring_cmd_setsockopt().

What's the reason to have that restriction?
And why is it only for the get path and not
the set path?

metze

[1] https://github.com/lxin/quic