Re: [PATCH v2 liburing] add helper functions to verify io_uring functionality

[Jens Axboe <axboe@kernel.dk>]

On 1/30/20 9:29 AM, Glauber Costa wrote:
> On Thu, Jan 30, 2020 at 11:13 AM Jens Axboe <axboe@kernel.dk> 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.

-- 
Jens Axboe