On 01/02/2020 20:52, Jens Axboe wrote: > 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@xxxxxxxxx> 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 :-) > Depends on how it's used, but I'd strive to inline __sys_io_uring_enter() to remove the extra indirect call into the shared lib. Though, not sure about packaging and all this stuff. May be useful to do that for liburing as well. -- Pavel Begunkov
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