From: Oleg Nesterov <[email protected]>
To: Jens Axboe <[email protected]>
Cc: [email protected], [email protected],
Peter Zijlstra <[email protected]>
Subject: Re: [PATCH 4/4] io_uring: flush task work before waiting for ring exit
Date: Thu, 9 Apr 2020 20:50:41 +0200 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
On 04/08, Jens Axboe wrote:
>
> So the question remains, we basically have this:
>
> A B
> task_work_run(tsk)
> task_work_add(tsk, io_poll_task_func())
> process cbs
> wait_for_completion()
>
> with the last wait needing to flush the work added on the B side, since
> that isn't part of the initial list.
I don't understand you, even remotely :/
maybe you can write some pseudo-code ?
who does wait_for_completion(), a callback? or this "tsk" after it does
task_work_run() ? Who does complete() ? How can this wait_for_completion()
help to flush the work added on the B side? And why do you need to do
something special to flush that work?
Could you also explain the comment above task_work_add() in
__io_async_wake() ?
If this fails, then the task is exiting.
OK,
If that is the case, then the exit check
which exit check?
will ultimately cancel these work items.
what does this mean? there is nothing to cancel if task_work_add() fails,
I guess this means something else...
Oleg.
next prev parent reply other threads:[~2020-04-09 18:50 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-07 16:02 [PATCHSET v2] io_uring and task_work interactions Jens Axboe
2020-04-07 16:02 ` [PATCH 1/4] task_work: add task_work_pending() helper Jens Axboe
2020-04-07 17:52 ` Jann Horn
2020-04-07 16:02 ` [PATCH 2/4] task_work: kill current->task_works checking in callers Jens Axboe
2020-04-07 16:02 ` [PATCH 3/4] task_work: make exit_work externally visible Jens Axboe
2020-04-07 16:02 ` [PATCH 4/4] io_uring: flush task work before waiting for ring exit Jens Axboe
2020-04-07 16:24 ` Oleg Nesterov
2020-04-07 16:38 ` Oleg Nesterov
2020-04-07 20:30 ` Jens Axboe
2020-04-07 20:39 ` Jens Axboe
2020-04-08 18:40 ` Oleg Nesterov
2020-04-08 18:48 ` Jens Axboe
2020-04-08 19:06 ` Jens Axboe
2020-04-08 20:17 ` Oleg Nesterov
2020-04-08 20:25 ` Jens Axboe
2020-04-08 21:19 ` Jens Axboe
2020-04-09 18:50 ` Oleg Nesterov [this message]
2020-04-10 0:29 ` Jens Axboe
-- strict thread matches above, loose matches on Subject: below --
2020-04-06 19:48 [PATCHSET 0/4] io_uring and task_work interactions Jens Axboe
2020-04-06 19:48 ` [PATCH 4/4] io_uring: flush task work before waiting for ring exit Jens Axboe
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