From: Pavel Begunkov <[email protected]>
To: Jens Axboe <[email protected]>, [email protected]
Subject: Re: [PATCH 1/1] io_uring: replace inflight_wait with tctx->wait
Date: Mon, 16 Nov 2020 16:48:34 +0000 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
On 16/11/2020 16:33, Jens Axboe wrote:
> On 11/15/20 5:56 AM, Pavel Begunkov wrote:
>> As tasks now cancel only theirs requests, and inflight_wait is awaited
>> only in io_uring_cancel_files(), which should be called with ->in_idle
>> set, instead of keeping a separate inflight_wait use tctx->wait.
>>
>> That will add some spurious wakeups but actually is safer from point of
>> not hanging the task.
>>
>> e.g.
>> task1 | IRQ
>> | *start* io_complete_rw_common(link)
>> | link: req1 -> req2 -> req3(with files)
>> *cancel_files() |
>> io_wq_cancel(), etc. |
>> | put_req(link), adds to io-wq req2
>> schedule() |
>>
>> So, task1 will never try to cancel req2 or req3. If req2 is
>> long-standing (e.g. read(empty_pipe)), this may hang.
>
> This looks like it's against 5.11, but also looks like we should add
> it for 5.10?
Yeah, 5.10 completely slipped my mind, I'll resend
--
Pavel Begunkov
next prev parent reply other threads:[~2020-11-16 16:52 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-15 12:56 [PATCH 1/1] io_uring: replace inflight_wait with tctx->wait Pavel Begunkov
2020-11-16 16:33 ` Jens Axboe
2020-11-16 16:48 ` Pavel Begunkov [this message]
2020-11-16 16:57 ` Jens Axboe
2020-11-16 17:16 ` Pavel Begunkov
2020-11-16 20:42 ` Jens Axboe
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