linux-kernel - Re: [PATCH] platform/surface: acpi-notify: add WQ_PERCPU to alloc

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Message-ID: <CAAofZF7GhnQ6nQyvLSbTPOv-k4Y=nM9BvoRNRJOA53bbWLo70g@mail.gmail.com>
Date: Wed, 19 Nov 2025 11:26:04 +0100
From: Marco Crivellari <marco.crivellari@...e.com>
To: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Cc: LKML <linux-kernel@...r.kernel.org>, platform-driver-x86@...r.kernel.org, 
	Tejun Heo <tj@...nel.org>, Lai Jiangshan <jiangshanlai@...il.com>, 
	Frederic Weisbecker <frederic@...nel.org>, Sebastian Andrzej Siewior <bigeasy@...utronix.de>, 
	Michal Hocko <mhocko@...e.com>, Maximilian Luz <luzmaximilian@...il.com>, 
	Hans de Goede <hansg@...nel.org>
Subject: Re: [PATCH] platform/surface: acpi-notify: add WQ_PERCPU to
 alloc_workqueue users

On Tue, Nov 18, 2025 at 3:43 PM Ilpo Järvinen
<ilpo.jarvinen@...ux.intel.com> wrote:
> [...]
> > What do you think, is it better in this way?
>
> Still quite non-specific to this particular change.
>
> > "
> > This continues the effort to refactor workqueue APIs, which began with
> > the introduction of new workqueues and a new alloc_workqueue flag in:
> >
> > commit 128ea9f6ccfb ("workqueue: Add system_percpu_wq and system_dfl_wq")
> > commit 930c2ea566af ("workqueue: Add new WQ_PERCPU flag")
> >
>
> The refactoring is going to alter the default behavior of ...
> [*].
>
> > For more details see the Link tag below.
>
>
>
> > This change adds a new WQ_PERCPU flag to explicitly request
>
> This change doesn't add a new flag, "explicitly request" part is correct
> though but as written things are mixed up.
>
> I'd just replace this paragraph and the next with something much simpler
> and more to the point:
>
> "In order to keep alloc_workqueue() behavior identical, explicitly request
> WQ_PERCPU."
>
> > alloc_workqueue() to be per-cpu when WQ_UNBOUND has not been specified.
> >
> > With the introduction of the WQ_PERCPU flag (equivalent to !WQ_UNBOUND),
> > any alloc_workqueue() caller that doesn’t explicitly specify WQ_UNBOUND
> > must now use WQ_PERCPU.
>
> This belongs earlier to description of the refactoring (to [*]).
>
> > Once migration is complete, WQ_UNBOUND can be removed and unbound will
> > become the implicit default.
>
> This is irrelevant detail about refactoring since WQ_PERCPU is used here.

Thanks for the suggestions, I think it should be ok now:

This continues the effort to refactor workqueue APIs, which began with
the introduction of new workqueues and a new alloc_workqueue flag in:

commit 128ea9f6ccfb ("workqueue: Add system_percpu_wq and system_dfl_wq")
commit 930c2ea566af ("workqueue: Add new WQ_PERCPU flag")

The refactoring is going to alter the default behavior of
alloc_workqueue() to be per-cpu when WQ_UNBOUND has not been specified.

With the introduction of the WQ_PERCPU flag (equivalent to !WQ_UNBOUND),
any alloc_workqueue() caller that doesn’t explicitly specify WQ_UNBOUND
must now use WQ_PERCPU.
For more details see the Link tag below.

In order to keep alloc_workqueue() behavior identical, explicitly request
WQ_PERCPU.


If it sounds good I will send the v2.

Thanks!


-- 

Marco Crivellari

L3 Support Engineer, Technology & Product