How to check if the kernel supports RECV_MULTISHOT?

[Berrysoft]

As it's an ioprio flag of the OP_RECV itself, I cannot check it's availability by probing the opcode.

[eqvinox]

open a unix socketpair() to yourself, submit a multishot receive, send yourself a packet, check if you get IORING_CQE_F_MORE on the CQE

Honestly, I would trust just trying more than any kind of feature indicator or version number check anyway.

[krisman]

Perhaps we can add some more support for detecting flags via the query operation that Pavel introduced. This won't solve the issue for older kernels, but at least will avoid increasing the pile of "detection code" from now on. I can take a look. Jens, Feel free to assign to me if you agree.