Extending the functionality of some SQE OPs

[Mark Papadakis <markuspapadakis@icloud.com>]

Would it make sense to extend the semantics of some OPS of specific syscalls to, for example, return in the CQE more than just an int (matching the semantics of the specific syscall they represent)?
For example, the respective OP for accept/accept4 returns an int for error or the fd of the accepted connection’s socket FD. But, given the clean-room implementation of io_uring, this may be a good opportunity to expand on it. Maybe there should be another field in the CQEs e.g
union {
	int i32;
	uint64_t u64;
	// whatever makes sense
} ret_ex;
Where the implementation of some OPs would access and set accordingly. For example, the OP for accept could set ret_ex.i32 to 1 if there are more outstanding FDs to be dequeued from the accepted connections queue, so that the application should accept again thereby draining it - as opposed to being woken up multiple times to do so. Other OPs may take advantage of this for other reasons.

Maybe it doesn’t make as much sense as I think it does, but if anything, it could become very useful down the road, once more syscalls(even OPs that are entirely new are not otherwise represent existing syscalls?) are implemented(invented?). 

@markpapadakis