Re: [PATCH 1/2] ath6kl: add WQ_PERCPU to alloc_workqueue users

[Marco Crivellari]

On Thu, Nov 13, 2025 at 5:12 PM Marco Crivellari
<marco.crivellari@xxxxxxxx> wrote:
>
> Currently if a user enqueues a work item using schedule_delayed_work() the
> used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use
> WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to
> schedule_work() that is using system_wq and queue_work(), that makes use
> again of WORK_CPU_UNBOUND.
>
> This lack of consistency cannot be addressed without refactoring the API.
> For more details see the Link tag below.
>
> alloc_workqueue() treats all queues as per-CPU by default, while unbound
> workqueues must opt-in via WQ_UNBOUND.
>
> This default is suboptimal: most workloads benefit from unbound queues,
> allowing the scheduler to place worker threads where they’re needed and
> reducing noise when CPUs are isolated.
>
> 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")
>
> This change adds a new WQ_PERCPU flag to explicitly request
> 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.
>
> Once migration is complete, WQ_UNBOUND can be removed and unbound will
> become the implicit default.
>
> Suggested-by: Tejun Heo <tj@xxxxxxxxxx>
> Signed-off-by: Marco Crivellari <marco.crivellari@xxxxxxxx>
> Link: https://lore.kernel.org/all/20250221112003.1dSuoGyc@xxxxxxxxxxxxx/
> ---
>  drivers/net/wireless/ath/ath6kl/usb.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/wireless/ath/ath6kl/usb.c b/drivers/net/wireless/ath/ath6kl/usb.c
> index 38bb501fc553..bfb21725d779 100644
> --- a/drivers/net/wireless/ath/ath6kl/usb.c
> +++ b/drivers/net/wireless/ath/ath6kl/usb.c
> @@ -637,7 +637,7 @@ static struct ath6kl_usb *ath6kl_usb_create(struct usb_interface *interface)
>         ar_usb = kzalloc(sizeof(struct ath6kl_usb), GFP_KERNEL);
>         if (ar_usb == NULL)
>                 return NULL;
> -       ar_usb->wq = alloc_workqueue("ath6kl_wq", 0, 0);
> +       ar_usb->wq = alloc_workqueue("ath6kl_wq", WQ_PERCPU, 0);
>         if (!ar_usb->wq) {
>                 kfree(ar_usb);
>                 return NULL;

[ Cc-ing Andrew Morton ]

Hello Andrew,

This file is orphaned. Can you help me in order to have this patch merged?

Thank you!

-- 

Marco Crivellari

L3 Support Engineer