linux-kernel - Re: [PATCH 0/2] don't use pid for request cancellation

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Message-ID: <d710004e-78be-67eb-283b-46949f34ecef@gmail.com>
Date:   Mon, 15 Jun 2020 19:01:29 +0300
From:   Pavel Begunkov <asml.silence@...il.com>
To:     Jens Axboe <axboe@...nel.dk>, io-uring@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     ebiederm@...ssion.com
Subject: Re: [PATCH 0/2] don't use pid for request cancellation

On 15/06/2020 18:04, Jens Axboe wrote:
> On 6/15/20 1:33 AM, Pavel Begunkov wrote:
>> Cancel requests of an extiting task based on ->task address. As
>> reported by Eric W. Biederman, using pid for this purpose is not
>> right.
>>
>> note: rebased on top of "cancel all" patches
> 
> Looks good, and I had the same thought of not grabbing a ref to the
> task for the cancel case where we don't need to dereference it.

I'm afraid of ABA problem, but this particular case @current shouldn't
go away until ->close is finished.

I was thinking about not get_task() it at all, but it would _at least_
need a way to add a callback on exit of tasks using io_uring to
cancel everything related there. Similarly to how it's done for
work->files using ->close().

-- 
Pavel Begunkov