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Date:   Tue, 11 Jul 2023 16:18:13 -0600
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Subject: Re: [PATCH 5/5] io_uring: add IORING_OP_WAITID support
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From:   Jens Axboe <axboe@kernel.dk>
To:     Arnd Bergmann <arnd@arndb.de>, io-uring@vger.kernel.org,
        linux-kernel@vger.kernel.org
Cc:     Christian Brauner <brauner@kernel.org>
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 <048cfbce-5238-2580-2d53-2ca740e72d79@kernel.dk>
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On 7/11/23 3:22 PM, Jens Axboe wrote:
> On 7/11/23 3:11?PM, Arnd Bergmann wrote:
>> On Tue, Jul 11, 2023, at 22:43, Jens Axboe wrote:
>>> This adds support for an async version of waitid(2), in a fully async
>>> version. If an event isn't immediately available, wait for a callback
>>> to trigger a retry.
>>>
>>> The format of the sqe is as follows:
>>>
>>> sqe->len		The 'which', the idtype being queried/waited for.
>>> sqe->fd			The 'pid' (or id) being waited for.
>>> sqe->file_index		The 'options' being set.
>>> sqe->addr2		A pointer to siginfo_t, if any, being filled in.
>>>
>>> buf_index, add3, and waitid_flags are reserved/unused for now.
>>> waitid_flags will be used for options for this request type. One
>>> interesting use case may be to add multi-shot support, so that the
>>> request stays armed and posts a notification every time a monitored
>>> process state change occurs.
>>>
>>> Note that this does not support rusage, on Arnd's recommendation.
>>>
>>> See the waitid(2) man page for details on the arguments.
>>>
>>> Signed-off-by: Jens Axboe <axboe@kernel.dk>
>>
>> Does this require argument conversion for compat tasks?
>>
>> Even without the rusage argument, I think the siginfo
>> remains incompatible with 32-bit tasks, unfortunately.
> 
> Hmm yes good point, if compat_siginfo and siginfo are different, then it
> does need handling for that. Would be a trivial addition, I'll make that
> change. Thanks Arnd!

Should be fixed in the current version:

https://git.kernel.dk/cgit/linux/commit/?h=io_uring-waitid&id=08f3dc9b7cedbd20c0f215f25c9a7814c6c601cc

-- 
Jens Axboe