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Date:   Tue, 11 Jul 2023 15:22:08 -0600
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Subject: Re: [PATCH 5/5] io_uring: add IORING_OP_WAITID support
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To:     Arnd Bergmann <arnd@arndb.de>, io-uring@vger.kernel.org,
        linux-kernel@vger.kernel.org
Cc:     Christian Brauner <brauner@kernel.org>
References: <20230711204352.214086-1-axboe@kernel.dk>
 <20230711204352.214086-6-axboe@kernel.dk>
 <8431d207-5e52-4f8c-a12d-276836174bad@app.fastmail.com>
From:   Jens Axboe <axboe@kernel.dk>
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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!

-- 
Jens Axboe