linux-kernel - [PATCH] iio/adc/pac1934: replace use of system_wq with system_percpu

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Message-ID: <20251105104330.111057-1-marco.crivellari@suse.com>
Date: Wed,  5 Nov 2025 11:43:30 +0100
From: Marco Crivellari <marco.crivellari@...e.com>
To: linux-kernel@...r.kernel.org,
	linux-iio@...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>,
	Marco Crivellari <marco.crivellari@...e.com>,
	Michal Hocko <mhocko@...e.com>,
	Marius Cristea <marius.cristea@...rochip.com>,
	Jonathan Cameron <jic23@...nel.org>
Subject: [PATCH] iio/adc/pac1934: replace use of system_wq with system_percpu_wq

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_percpu_wq replaced system_wq, so change the wq in iio/adc/pac1934.

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>
---
 drivers/iio/adc/pac1934.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iio/adc/pac1934.c b/drivers/iio/adc/pac1934.c
index 48df16509260..ec96bb0f2ed6 100644
--- a/drivers/iio/adc/pac1934.c
+++ b/drivers/iio/adc/pac1934.c
@@ -768,7 +768,7 @@ static int pac1934_retrieve_data(struct pac1934_chip_info *info,
 		 * Re-schedule the work for the read registers on timeout
 		 * (to prevent chip registers saturation)
 		 */
-		mod_delayed_work(system_wq, &info->work_chip_rfsh,
+		mod_delayed_work(system_percpu_wq, &info->work_chip_rfsh,
 				 msecs_to_jiffies(PAC1934_MAX_RFSH_LIMIT_MS));
 	}

-- 
2.51.1