Re: liburing: expose syscalls?

[Andres Freund <andres@anarazel.de>]

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?

Andres
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