[PATCH] thermal: core: Add WQ_PERCPU to alloc_workqueue users

[PATCH] thermal: core: Add WQ_PERCPU to alloc_workqueue users

[Marco Crivellari]

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 unbound by default.

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.

Link: https://lore.kernel.org/all/20250221112003.1dSuoGyc@linutronix.de/
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
---
 drivers/thermal/thermal_core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index 2f4e2dc46b8f..691c5e749c3e 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -1889,7 +1889,8 @@ static int __init thermal_init(void)
 	if (result)
 		goto error;
 
-	thermal_wq = alloc_workqueue("thermal_events", WQ_POWER_EFFICIENT, 0);
+	thermal_wq = alloc_workqueue("thermal_events",
+				     WQ_POWER_EFFICIENT | WQ_PERCPU, 0);
 	if (!thermal_wq) {
 		result = -ENOMEM;
 		goto unregister_netlink;
-- 
2.54.0

Re: [PATCH] thermal: core: Add WQ_PERCPU to alloc_workqueue users

[Rafael J. Wysocki]

On Thu, May 14, 2026 at 3:29 PM Marco Crivellari
<marco.crivellari@suse.com> wrote:
>
> 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 unbound by default.
>
> 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.
>
> Link: https://lore.kernel.org/all/20250221112003.1dSuoGyc@linutronix.de/
> Suggested-by: Tejun Heo <tj@kernel.org>
> Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
> ---
>  drivers/thermal/thermal_core.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> index 2f4e2dc46b8f..691c5e749c3e 100644
> --- a/drivers/thermal/thermal_core.c
> +++ b/drivers/thermal/thermal_core.c
> @@ -1889,7 +1889,8 @@ static int __init thermal_init(void)
>         if (result)
>                 goto error;
>
> -       thermal_wq = alloc_workqueue("thermal_events", WQ_POWER_EFFICIENT, 0);
> +       thermal_wq = alloc_workqueue("thermal_events",
> +                                    WQ_POWER_EFFICIENT | WQ_PERCPU, 0);

No, we actually don't want that here.  See

26fd03effa94 thermal: core: Adjust thermal_wq allocation flags

>         if (!thermal_wq) {
>                 result = -ENOMEM;
>                 goto unregister_netlink;
> --

Re: [PATCH] thermal: core: Add WQ_PERCPU to alloc_workqueue users

[Marco Crivellari]

On Thu, May 14, 2026 at 3:53 PM Rafael J. Wysocki <rafael@kernel.org> wrote:
> [...]
> > diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> > index 2f4e2dc46b8f..691c5e749c3e 100644
> > --- a/drivers/thermal/thermal_core.c
> > +++ b/drivers/thermal/thermal_core.c
> > @@ -1889,7 +1889,8 @@ static int __init thermal_init(void)
> >         if (result)
> >                 goto error;
> >
> > -       thermal_wq = alloc_workqueue("thermal_events", WQ_POWER_EFFICIENT, 0);
> > +       thermal_wq = alloc_workqueue("thermal_events",
> > +                                    WQ_POWER_EFFICIENT | WQ_PERCPU, 0);
>
> No, we actually don't want that here.  See
>
> 26fd03effa94 thermal: core: Adjust thermal_wq allocation flags
>
> >         if (!thermal_wq) {
> >                 result = -ENOMEM;
> >                 goto unregister_netlink;
> > --

Thanks for sharing the commit, I didn't see it.
Quoting from the commit log:

> The thermal workqueue doesn't need to be freezable or per-CPU
> [...]

Currently, alloc_workqueue() without WQ_PERCPU is already per-cpu,
so drop this flag it doesn't make the workqueue unbound.

If you want it unbound WQ_UNBOUND must be used.
If it's okay with you, I will send the v2 with WQ_UNBOUND.

Thanks!

-- 

Marco Crivellari

SUSE Labs

Re: [PATCH] thermal: core: Add WQ_PERCPU to alloc_workqueue users

[Rafael J. Wysocki]

On Thu, May 14, 2026 at 4:03 PM Marco Crivellari
<marco.crivellari@suse.com> wrote:
>
> On Thu, May 14, 2026 at 3:53 PM Rafael J. Wysocki <rafael@kernel.org> wrote:
> > [...]
> > > diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> > > index 2f4e2dc46b8f..691c5e749c3e 100644
> > > --- a/drivers/thermal/thermal_core.c
> > > +++ b/drivers/thermal/thermal_core.c
> > > @@ -1889,7 +1889,8 @@ static int __init thermal_init(void)
> > >         if (result)
> > >                 goto error;
> > >
> > > -       thermal_wq = alloc_workqueue("thermal_events", WQ_POWER_EFFICIENT, 0);
> > > +       thermal_wq = alloc_workqueue("thermal_events",
> > > +                                    WQ_POWER_EFFICIENT | WQ_PERCPU, 0);
> >
> > No, we actually don't want that here.  See
> >
> > 26fd03effa94 thermal: core: Adjust thermal_wq allocation flags
> >
> > >         if (!thermal_wq) {
> > >                 result = -ENOMEM;
> > >                 goto unregister_netlink;
> > > --
>
> Thanks for sharing the commit, I didn't see it.
> Quoting from the commit log:
>
> > The thermal workqueue doesn't need to be freezable or per-CPU
> > [...]
>
> Currently, alloc_workqueue() without WQ_PERCPU is already per-cpu,
> so drop this flag it doesn't make the workqueue unbound.
>
> If you want it unbound WQ_UNBOUND must be used.
> If it's okay with you, I will send the v2 with WQ_UNBOUND.

Yes, please!