On Fri, Jan 31, 2020 at 10:14 AM Jens Axboe <axboe@xxxxxxxxx> wrote: > > On 1/31/20 6:52 AM, Glauber Costa wrote: > > On Thu, Jan 30, 2020 at 11:31 AM Jens Axboe <axboe@xxxxxxxxx> wrote: > >> > >> On 1/30/20 9:29 AM, Glauber Costa wrote: > >>> On Thu, Jan 30, 2020 at 11:13 AM Jens Axboe <axboe@xxxxxxxxx> wrote: > >>>> > >>>> On 1/30/20 9:00 AM, Glauber Costa wrote: > >>>>> It is common for an application using an ever-evolving interface to want > >>>>> to inquire about the presence of certain functionality it plans to use. > >>>>> > >>>>> Information about opcodes is stored in a io_uring_probe structure. There > >>>>> is usually some boilerplate involved in initializing one, and then using > >>>>> it to check if it is enabled. > >>>>> > >>>>> This patch adds two new helper functions: one that returns a pointer to > >>>>> a io_uring_probe (or null if it probe is not available), and another one > >>>>> that given a probe checks if the opcode is supported. > >>>> > >>>> This looks good, I committed it with minor changes. > >>>> > >>>> On top of this, we should have a helper that doesn't need a ring. So > >>>> basically one that just sets up a ring, calls io_uring_get_probe(), > >>>> then tears down the ring. > >>>> > >>> I'd be happy to follow up with that. > >>> > >>> Just to be sure, the information returned by probe should be able to outlive the > >>> tear down of the ring, right ? > >> > >> Yeah, same lifetime as the helper you have now, caller must free it once > >> done. > > > > Well, in hindsight, I should have called that > > io_uring_get_probe_ring() so io_uring_get_probe() > > doesn't take a ring. > > Just change it - we just added it yesterday, and it's not released yet. > I don't break anything that's been in a release, and I maintain > compatibility between releases, but we can change it now. Yeah, I figured as much and ended up changing it. > > > Alternatively, to keep things in a single function, I can change > > io_uring_get_probe() so that if it > > ring is NULL, we do our own allocation. > > > > I actually kind of like that. Would that work for you ? > > Not a huge deal to me, we can go that route. > > -- > Jens Axboe >
