Re: liburing: expose syscalls?

[Jens Axboe <axboe@kernel.dk>]

On 2/1/20 5:53 AM, Andres Freund wrote:
> Hi,
> 
> As long as the syscalls aren't exposed by glibc it'd be useful - at
> least for me - to have liburing expose the syscalls without really going
> through liburing facilities...
> 
> Right now I'm e.g. using a "raw" io_uring_enter(IORING_ENTER_GETEVENTS)
> to be able to have multiple processes safely wait for events on the same
> uring, without needing to hold the lock [1] protecting the ring [2].  It's
> probably a good idea to add a liburing function to be able to do so, but
> I'd guess there are going to continue to be cases like that. In a bit
> of time it seems likely that at least open source users of uring that
> are included in databases, have to work against multiple versions of
> liburing (as usually embedding libs is not allowed), and sometimes that
> is easier if one can backfill a function or two if necessary.
> 
> That syscall should probably be under a name that won't conflict with
> eventual glibc implementation of the syscall.
> 
> Obviously I can just do the syscall() etc myself, but it seems
> unnecessary to have a separate copy of the ifdefs for syscall numbers
> etc.
> 
> What do you think?

Not sure what I'm missing here, but liburing already has
__sys_io_uring_enter() for this purpose, and ditto for the register
and setup functions?

-- 
Jens Axboe