[Intel-gfx] How to convert drivers/gpu/drm/i915/ to use local workqueue?

[Tetsuo Handa]

On 2022/06/30 16:46, Tvrtko Ursulin wrote:
> 
> Hi,
> 
> On 10/06/2022 15:57, Tetsuo Handa wrote:
>> Hello.
>>
>> Like commit c4f135d643823a86 ("workqueue: Wrap flush_workqueue() using
>> a macro") explains, we are removing flush_scheduled_work() calls. And now
>>
>>    drivers/gpu/drm/i915/display/intel_display.c
>>    drivers/gpu/drm/i915/gt/selftest_execlists.c
>>
>> are the last flush_scheduled_work() callers which have no patch proposed.
>> I want to make a patch like
>> https://lkml.kernel.org/r/e9b95132-89cd-5cfc-1a09-966393c5ecb0@I-love.SAKURA.ne.jp
>> but I couldn't understand how to interpret drivers/gpu/drm/i915/ part.
> 
> Could you provide some more context please? I did not immediately understand
> whether the goal is remove flush_schedule_work helper with no arguments, or
> actually stop drivers using the system work queues.

The goal is to remove flush_schedule_work().

Any kernel module is expected to stop using system workqueues if that module
needs to call flush_scheduled_work() or flush_workqueue(system_*_wq).
Continuing use of system workqueues is OK as long as that module does not
need to call flush_scheduled_work() nor flush_workqueue(system_*_wq).

All in-tree kernel modules stopped calling flush_workqueue(system_*_wq) in 5.19.

Many of in-tree kernel modules already have patches for stop calling
flush_scheduled_work(). But gpu/drm/i915 is one of in-tree kernel modules
which do not have patches for stop calling flush_scheduled_work().

I want help from those who are familiar with this module.

Regards.