netdev - [PATCH net-next v2 1/3] net: replace use of system_unbound_wq with system_dfl

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Message-ID: <20250918142427.309519-2-marco.crivellari@suse.com>
Date: Thu, 18 Sep 2025 16:24:25 +0200
From: Marco Crivellari <marco.crivellari@...e.com>
To: linux-kernel@...r.kernel.org,
	netdev@...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>,
	"David S . Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>
Subject: [PATCH net-next v2 1/3] net: replace use of system_unbound_wq with system_dfl_wq

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.

system_unbound_wq should be the default workqueue so as not to enforce
locality constraints for random work whenever it's not required.

Adding system_dfl_wq to encourage its use when unbound work should be used.

The old system_unbound_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/net/macvlan.c       | 2 +-
 drivers/net/netdevsim/dev.c | 6 +++---
 net/core/link_watch.c       | 4 ++--
 net/unix/garbage.c          | 2 +-
 4 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
index 4df991e494bd..7966545512cf 100644
--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -369,7 +369,7 @@ static void macvlan_broadcast_enqueue(struct macvlan_port *port,
 	}
 	spin_unlock(&port->bc_queue.lock);
 
-	queue_work(system_unbound_wq, &port->bc_work);
+	queue_work(system_dfl_wq, &port->bc_work);
 
 	if (err)
 		goto free_nskb;
diff --git a/drivers/net/netdevsim/dev.c b/drivers/net/netdevsim/dev.c
index 2672d071b325..95f66c1f59db 100644
--- a/drivers/net/netdevsim/dev.c
+++ b/drivers/net/netdevsim/dev.c
@@ -851,7 +851,7 @@ static void nsim_dev_trap_report_work(struct work_struct *work)
 	nsim_dev = nsim_trap_data->nsim_dev;
 
 	if (!devl_trylock(priv_to_devlink(nsim_dev))) {
-		queue_delayed_work(system_unbound_wq,
+		queue_delayed_work(system_dfl_wq,
 				   &nsim_dev->trap_data->trap_report_dw, 1);
 		return;
 	}
@@ -867,7 +867,7 @@ static void nsim_dev_trap_report_work(struct work_struct *work)
 		cond_resched();
 	}
 	devl_unlock(priv_to_devlink(nsim_dev));
-	queue_delayed_work(system_unbound_wq,
+	queue_delayed_work(system_dfl_wq,
 			   &nsim_dev->trap_data->trap_report_dw,
 			   msecs_to_jiffies(NSIM_TRAP_REPORT_INTERVAL_MS));
 }
@@ -924,7 +924,7 @@ static int nsim_dev_traps_init(struct devlink *devlink)
 
 	INIT_DELAYED_WORK(&nsim_dev->trap_data->trap_report_dw,
 			  nsim_dev_trap_report_work);
-	queue_delayed_work(system_unbound_wq,
+	queue_delayed_work(system_dfl_wq,
 			   &nsim_dev->trap_data->trap_report_dw,
 			   msecs_to_jiffies(NSIM_TRAP_REPORT_INTERVAL_MS));
 
diff --git a/net/core/link_watch.c b/net/core/link_watch.c
index 864f3bbc3a4c..212cde35affa 100644
--- a/net/core/link_watch.c
+++ b/net/core/link_watch.c
@@ -157,9 +157,9 @@ static void linkwatch_schedule_work(int urgent)
 	 * override the existing timer.
 	 */
 	if (test_bit(LW_URGENT, &linkwatch_flags))
-		mod_delayed_work(system_unbound_wq, &linkwatch_work, 0);
+		mod_delayed_work(system_dfl_wq, &linkwatch_work, 0);
 	else
-		queue_delayed_work(system_unbound_wq, &linkwatch_work, delay);
+		queue_delayed_work(system_dfl_wq, &linkwatch_work, delay);
 }
 
 
diff --git a/net/unix/garbage.c b/net/unix/garbage.c
index 01e2b9452c75..684ab03137b6 100644
--- a/net/unix/garbage.c
+++ b/net/unix/garbage.c
@@ -592,7 +592,7 @@ static DECLARE_WORK(unix_gc_work, __unix_gc);
 void unix_gc(void)
 {
 	WRITE_ONCE(gc_in_progress, true);
-	queue_work(system_unbound_wq, &unix_gc_work);
+	queue_work(system_dfl_wq, &unix_gc_work);
 }
 
 #define UNIX_INFLIGHT_TRIGGER_GC 16000
-- 
2.51.0