linux-kernel - Re: [PATCH] drm/vc4: hdmi: replace use of system_wq with system_percpu

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <7bfb8769-6987-49bb-b56c-b840697966a8@igalia.com>
Date: Sat, 7 Feb 2026 17:44:24 -0300
From: Maíra Canal <mcanal@...lia.com>
To: Marco Crivellari <marco.crivellari@...e.com>,
 linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org
Cc: 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>, Maxime Ripard <mripard@...nel.org>,
 Dave Stevenson <dave.stevenson@...pberrypi.com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>,
 Simona Vetter <simona@...ll.ch>
Subject: Re: [PATCH] drm/vc4: hdmi: replace use of system_wq with
 system_percpu_wq

Hi Marco,

On 05/11/25 07:11, Marco Crivellari 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.
> 
> This patch continues the effort to refactor worqueue APIs, which has begun
> with the change introducing new workqueues and a new alloc_workqueue flag:
> 
> commit 128ea9f6ccfb ("workqueue: Add system_percpu_wq and system_dfl_wq")
> commit 930c2ea566af ("workqueue: Add new WQ_PERCPU flag")
> 
> system_wq should be the per-cpu workqueue, yet in this name nothing makes
> that clear, so replace system_wq with system_percpu_wq.
> 
> The old wq (system_wq) will be kept for a few release cycles.
> 
> Suggested-by: Tejun Heo <tj@...nel.org>
> Signed-off-by: Marco Crivellari <marco.crivellari@...e.com>

Reviewed-by: Maíra Canal <mcanal@...lia.com>

Will this patch go through DRM trees? If so, let me know and I can push
it to drm-misc-next.

Best regards,
- Maíra

> ---
>   drivers/gpu/drm/vc4/vc4_hdmi.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
> index 07c91b450f93..c39cf1530f23 100644
> --- a/drivers/gpu/drm/vc4/vc4_hdmi.c
> +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
> @@ -745,7 +745,7 @@ static void vc4_hdmi_enable_scrambling(struct drm_encoder *encoder)
>   
>   	vc4_hdmi->scdc_enabled = true;
>   
> -	queue_delayed_work(system_wq, &vc4_hdmi->scrambling_work,
> +	queue_delayed_work(system_percpu_wq, &vc4_hdmi->scrambling_work,
>   			   msecs_to_jiffies(SCRAMBLING_POLLING_DELAY_MS));
>   }
>   
> @@ -794,7 +794,7 @@ static void vc4_hdmi_scrambling_wq(struct work_struct *work)
>   	drm_scdc_set_high_tmds_clock_ratio(connector, true);
>   	drm_scdc_set_scrambling(connector, true);
>   
> -	queue_delayed_work(system_wq, &vc4_hdmi->scrambling_work,
> +	queue_delayed_work(system_percpu_wq, &vc4_hdmi->scrambling_work,
>   			   msecs_to_jiffies(SCRAMBLING_POLLING_DELAY_MS));
>   }
>