Re: [PATCH 3/3] io_uring: tweak io_req_task_work_add

[Pavel Begunkov <asml.silence@gmail.com>]

On 6/30/21 10:17 PM, Jens Axboe wrote:
> On 6/30/21 2:54 PM, Pavel Begunkov wrote:
>> Whenever possible we don't want to fallback a request. task_work_add()
>> will be fine if the task is exiting, so don't check for PF_EXITING,
>> there is anyway only a relatively small gap between setting the flag
>> and doing the final task_work_run().
>>
>> Also add likely for the hot path.
> 
> I'm not a huge fan of likely/unlikely, and in particular constructs like:
> 
>> -	if (test_bit(0, &tctx->task_state) ||
>> +	if (likely(test_bit(0, &tctx->task_state)) ||
>>  	    test_and_set_bit(0, &tctx->task_state))
>>  		return 0;
> 
> where the state is combined. In any case, it should be a separate
> change. If there's an "Also" paragraph in a patch, then that's also
> usually a good clue that that particular change should've been
> separate :-)

Not sure what's wrong with likely above, but how about drop
this one then?

-- 
Pavel Begunkov