Re: [PATCH] io_uring: fix race with shadow drain deferrals

[Jens Axboe <axboe@kernel.dk>]

On 11/20/19 7:07 PM, Jackie Liu wrote:
> 
> 
>> 2019年11月21日 07:14，Jens Axboe <axboe@kernel.dk> 写道：
>>
>> On 11/20/19 6:57 PM, Jackie Liu wrote:
>>>> @@ -2957,15 +2975,14 @@ static void io_queue_sqe(struct io_kiocb *req)
>>>> 	int ret;
>>>>
>>>> 	ret = io_req_defer(req);
>>>> -	if (ret) {
>>>> -		if (ret != -EIOCBQUEUED) {
>>>> -			io_cqring_add_event(req, ret);
>>>> -			if (req->flags & REQ_F_LINK)
>>>> -				req->flags |= REQ_F_FAIL_LINK;
>>>> -			io_double_put_req(req);
>>>> -		}
>>>> -	} else
>>>> +	if (!ret) {
>>>> 		__io_queue_sqe(req);
>>>> +	} else if (ret != -EIOCBQUEUED) {
>>>> +		io_cqring_add_event(req, ret);
>>>> +		if (req->flags & REQ_F_LINK)
>>>> +			req->flags |= REQ_F_FAIL_LINK;
>>>> +		io_double_put_req(req);
>>>> +	}
>>>> }
>>>
>>> Hmm.. Why we need rewrite there? clear code? Seems to be unrelated to
>>> this issue.
>>
>> We don't need to, and the previous patch touched it, but it's much
>> easier to read after this change. Before it was:
>>
>> if (ret) {
>> 	if (ret != -EIOCBQUEUED) {
>> 		...
>> 	}
>> } else {
>> 	...
>> }
>>
>> which is now just
>>
>> if (!ret) {
>> 	...
>> } else if (ret != -EIOCBQUEUED) {
>> 	...
>> }
>>
>> not related to the change really, but kind of silly to make a separate
>> patch for imho.
>>
> 
> Understand, thanks for explaining and fixing this problem,
> And now, please add:
> 
> Reviewed-by: Jackie Liu <liuyun01@kylinos.cn>

Thanks for reviewing it, I've added your reviewed-by.

-- 
Jens Axboe