linux-kernel - Re: [PATCH v2 0/5] fast poll multishot mode

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Message-ID: <3f940dad-73ce-4ea6-dc76-f877c64dbb9a@gmail.com>
Date:   Fri, 6 May 2022 17:01:25 +0100
From:   Pavel Begunkov <asml.silence@...il.com>
To:     Jens Axboe <axboe@...nel.dk>, Hao Xu <haoxu.linux@...il.com>,
        io-uring@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 0/5] fast poll multishot mode

On 5/6/22 15:18, Jens Axboe wrote:
> On 5/6/22 1:36 AM, Hao Xu wrote:
>> Hi All,
>> I actually had a question about the current poll code, from the code it
>> seems when we cancel a poll-like request, it will ignore the existing
>> events and just raise a -ECANCELED cqe though I haven't tested it. Is
>> this by design or am I missing something?
> 
> That's by design, but honestly I don't think anyone considered the case
> where it's being canceled but has events already. For that case, I think
> we should follow the usual logic of only returning an error (canceled)
> if we don't have events, if we have events just return them. For
> multi-shot, obviously also terminate, but same logic there.

Why would we care? It's inherently racy in any case and any
user not handling this is already screwed.

-- 
Pavel Begunkov