linux-kernel - [PATCH 1/1] wifi: libertas: WQ_PERCPU added to alloc

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Message-ID: <20250922102407.186660-2-marco.crivellari@suse.com>
Date: Mon, 22 Sep 2025 12:24:07 +0200
From: Marco Crivellari <marco.crivellari@...e.com>
To: linux-kernel@...r.kernel.org,
	linux-wireless@...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>,
	Johannes Berg <johannes.berg@...el.com>,
	Francesco Dolcini <francesco.dolcini@...adex.com>,
	Brian Norris <briannorris@...omium.org>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Kalle Valo <kvalo@...nel.org>,
	"Dr . David Alan Gilbert" <linux@...blig.org>,
	Jeff Chen <jeff.chen_1@....com>,
	Stefan Kerkmann <s.kerkmann@...gutronix.de>
Subject: [PATCH 1/1] wifi: libertas: WQ_PERCPU added to alloc_workqueue users

Currently if a user enqueue 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 consistentcy cannot be addressed without refactoring the API.

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 change add a new WQ_PERCPU flag, to explicitly request the use of
the per-CPU behavior. Both flags coexist for one release cycle to allow
callers to transition their calls.

Once migration is complete, WQ_UNBOUND can be removed and unbound will
become the implicit 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.

All existing users have been updated accordingly.

Suggested-by: Tejun Heo <tj@...nel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@...e.com>
---
 drivers/net/wireless/marvell/libertas/if_sdio.c | 3 ++-
 drivers/net/wireless/marvell/libertas/if_spi.c  | 3 ++-
 drivers/net/wireless/marvell/libertas_tf/main.c | 2 +-
 3 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/marvell/libertas/if_sdio.c b/drivers/net/wireless/marvell/libertas/if_sdio.c
index 524034699972..1e29e80cad61 100644
--- a/drivers/net/wireless/marvell/libertas/if_sdio.c
+++ b/drivers/net/wireless/marvell/libertas/if_sdio.c
@@ -1181,7 +1181,8 @@ static int if_sdio_probe(struct sdio_func *func,
 	spin_lock_init(&card->lock);
 	INIT_LIST_HEAD(&card->packets);
 
-	card->workqueue = alloc_workqueue("libertas_sdio", WQ_MEM_RECLAIM, 0);
+	card->workqueue = alloc_workqueue("libertas_sdio",
+					  WQ_MEM_RECLAIM | WQ_PERCPU, 0);
 	if (unlikely(!card->workqueue)) {
 		ret = -ENOMEM;
 		goto err_queue;
diff --git a/drivers/net/wireless/marvell/libertas/if_spi.c b/drivers/net/wireless/marvell/libertas/if_spi.c
index b722a6587fd3..699bae8971f8 100644
--- a/drivers/net/wireless/marvell/libertas/if_spi.c
+++ b/drivers/net/wireless/marvell/libertas/if_spi.c
@@ -1153,7 +1153,8 @@ static int if_spi_probe(struct spi_device *spi)
 	priv->fw_ready = 1;
 
 	/* Initialize interrupt handling stuff. */
-	card->workqueue = alloc_workqueue("libertas_spi", WQ_MEM_RECLAIM, 0);
+	card->workqueue = alloc_workqueue("libertas_spi",
+					  WQ_MEM_RECLAIM | WQ_PERCPU, 0);
 	if (!card->workqueue) {
 		err = -ENOMEM;
 		goto remove_card;
diff --git a/drivers/net/wireless/marvell/libertas_tf/main.c b/drivers/net/wireless/marvell/libertas_tf/main.c
index d1067874428f..c51091e7c6c6 100644
--- a/drivers/net/wireless/marvell/libertas_tf/main.c
+++ b/drivers/net/wireless/marvell/libertas_tf/main.c
@@ -708,7 +708,7 @@ EXPORT_SYMBOL_GPL(lbtf_bcn_sent);
 static int __init lbtf_init_module(void)
 {
 	lbtf_deb_enter(LBTF_DEB_MAIN);
-	lbtf_wq = alloc_workqueue("libertastf", WQ_MEM_RECLAIM, 0);
+	lbtf_wq = alloc_workqueue("libertastf", WQ_MEM_RECLAIM | WQ_PERCPU, 0);
 	if (lbtf_wq == NULL) {
 		printk(KERN_ERR "libertastf: couldn't create workqueue\n");
 		return -ENOMEM;
-- 
2.51.0