Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <3f940dad-73ce-4ea6-dc76-f877c64dbb9a@gmail.com>
Date:   Fri, 6 May 2022 17:01:25 +0100
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101
 Thunderbird/91.8.1
Subject: Re: [PATCH v2 0/5] fast poll multishot mode
Content-Language: en-US
To:     Jens Axboe <axboe@kernel.dk>, Hao Xu <haoxu.linux@gmail.com>,
        io-uring@vger.kernel.org
Cc:     linux-kernel@vger.kernel.org
References: <20220506070102.26032-1-haoxu.linux@gmail.com>
 <b4d23f42-36f4-353a-1f44-c12178f0a2b3@gmail.com>
 <5ce3d6c7-42f9-28c3-0800-4da399adaaea@kernel.dk>
From:   Pavel Begunkov <asml.silence@gmail.com>
In-Reply-To: <5ce3d6c7-42f9-28c3-0800-4da399adaaea@kernel.dk>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk

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