The following commit has been merged into the smp/core branch of tip:

Commit-ID:     7eb28030f641d5bc7682c98602f896304efd31d2
Gitweb:        https://git.kernel.org/tip/7eb28030f641d5bc7682c98602f896304efd31d2
Author:        Marco Crivellari <marco.crivellari@suse.com>
AuthorDate:    Mon, 10 Nov 2025 18:03:32 +01:00
Committer:     Thomas Gleixner <tglx@kernel.org>
CommitterDate: Thu, 26 Mar 2026 17:31:35 +01:00

smp: Use system_percpu_wq instead of system_wq

When a caller enqueues a work item using schedule_delayed_work() the used
wq is "system_wq" (per-cpu wq) while queue_delayed_work() uses
WORK_CPU_UNBOUND (used when no target CPU is specified). The same applies
to schedule_work() that is using system_wq and queue_work(), which again
makes use of WORK_CPU_UNBOUND.

This lack of consistency cannot be addressed without refactoring the API.

Continue the effort to refactor workqueue APIs, which began with the
introduction of new workqueues and a new alloc_workqueue() flag in:

  commit 128ea9f6ccfb ("workqueue: Add system_percpu_wq and system_dfl_wq")
  commit 930c2ea566af ("workqueue: Add new WQ_PERCPU flag")

and switch smp_call_on_cpu() to use system_percpu_wq because system_wq is
going away once the ongoing workqueue restructuring is done.

Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://patch.msgid.link/20251110170332.319314-1-marco.crivellari@suse.com
---
 kernel/smp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/smp.c b/kernel/smp.c
index 0fc4ff2..6c77848 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -1185,7 +1185,7 @@ int smp_call_on_cpu(unsigned int cpu, int (*func)(void *), void *par, bool phys)
 	if (cpu >= nr_cpu_ids || !cpu_online(cpu))
 		return -ENXIO;
 
-	queue_work_on(cpu, system_wq, &sscs.work);
+	queue_work_on(cpu, system_percpu_wq, &sscs.work);
 	wait_for_completion(&sscs.done);
 	destroy_work_on_stack(&sscs.work);