linux-kernel - Re: [PATCH] mmc: mtk-sd: replace use of system_wq with system_percpu

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Message-ID: <9fbec168-295a-4278-93f4-e27a419c892f@collabora.com>
Date: Wed, 5 Nov 2025 16:40:01 +0100
From: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
To: Marco Crivellari <marco.crivellari@...e.com>,
 linux-kernel@...r.kernel.org, linux-mediatek@...ts.infradead.org,
 linux-arm-kernel@...ts.infradead.org, linux-mmc@...r.kernel.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>, Chaotian Jing <chaotian.jing@...iatek.com>,
 Ulf Hansson <ulf.hansson@...aro.org>,
 Matthias Brugger <matthias.bgg@...il.com>
Subject: Re: [PATCH] mmc: mtk-sd: replace use of system_wq with
 system_percpu_wq

Il 05/11/25 15:58, Marco Crivellari ha scritto:
> 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")
> 
> Replace system_wq with system_percpu_wq, keeping the same old behavior.
> 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: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>