Re: [PATCH v4 1/2] io_uring: avoid whole io_wq_work copy for requests completed inline

[Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com>]

hi,

> On 31/05/2020 19:15, Xiaoguang Wang wrote:
>> In the begin of __io_splice_prep or io_close_prep, current io_uring mainline codes will
>> modify req->work.flags firstly, so we need to call io_req_init_async to initialize
>> io_wq_work before the work.flags modification.
>> For below codes:
>> static inline void io_req_init_async(struct io_kiocb *req,
>>                          void (*func)(struct io_wq_work **))
>> {
>>          if (req->flags & REQ_F_WORK_INITIALIZED) {
>>                  if (!req->work.func)
>>                          req->work.func = func;
>>          } else {
>>                  req->work = (struct io_wq_work){ .func = func };
>>                  req->flags |= REQ_F_WORK_INITIALIZED;
>>          }
>> }
>>
>> if we not pass NULL to parameter 'func', e.g. pass io_wq_submit_work, then
>> we can not use io_req_init_async() to pass io_close_finish again.
> 
> It's not as bad, just the thing you poked is overused and don't have strict rules.
> I have a feeling, that for it to be done right it'd need more fundamental refactoring
> with putting everything related to ->work closer to io_queue_async_work().
Yes, I totally agree with you, that would be safer.

Regards,
Xiaoguang Wang

> 
>>
>> Now I'm confused how to write better codes based on current io_uring mainline codes :)
>> If you have some free time, please have a deeper look, thanks.
>