On 8/10/20 2:32 PM, Peter Zijlstra wrote:
> On Mon, Aug 10, 2020 at 02:25:48PM -0600, Jens Axboe wrote:
>> On 8/10/20 2:13 PM, Jens Axboe wrote:
>>>> Would it be clearer to write it like so perhaps?
>>>>
>>>> /*
>>>> * Optimization; when the task is RUNNING we can do with a
>>>> * cheaper TWA_RESUME notification because,... <reason goes
>>>> * here>. Otherwise do the more expensive, but always correct
>>>> * TWA_SIGNAL.
>>>> */
>>>> if (READ_ONCE(tsk->state) == TASK_RUNNING) {
>>>> __task_work_notify(tsk, TWA_RESUME);
>>>> if (READ_ONCE(tsk->state) == TASK_RUNNING)
>>>> return;
>>>> }
>>>> __task_work_notify(tsk, TWA_SIGNAL);
>>>> wake_up_process(tsk);
>>>
>>> Yeah that is easier to read, wasn't a huge fan of the loop since it's
>>> only a single retry kind of condition. I'll adopt this suggestion,
>>> thanks!
>>
>> Re-write it a bit on top of that, just turning it into two separate
>> READ_ONCE, and added appropriate comments. For the SQPOLL case, the
>> wake_up_process() is enough, so we can clean up that if/else.
>>
>> https://git.kernel.dk/cgit/linux-block/commit/?h=io_uring-5.9&id=49bc5c16483945982cf81b0109d7da7cd9ee55ed
>
> OK, that works for me, thanks!
>
> Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Thanks for checking (again) - I've added your acked-by.
--
Jens Axboe
