Re: liburing: expose syscalls?

[Jens Axboe <axboe@kernel.dk>]

On 2/1/20 10:49 AM, Andres Freund wrote:
> Hi, 
> 
> On February 1, 2020 6:39:41 PM GMT+01:00, Jens Axboe <axboe@kernel.dk> wrote:
>> 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?
> 
> Aren't they hidden to the outside by the symbol versioning script?

So you just want to have them exposed? I'd be fine with that. I'll
take a patch :-)

-- 
Jens Axboe