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McKenney" , Mathieu Desnoyers Subject: [PATCH 1/1] smp: replace use of system_wq with system_percpu_wq Date: Fri, 5 Sep 2025 11:09:53 +0200 Message-ID: <20250905090953.109082-2-marco.crivellari@suse.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20250905090953.109082-1-marco.crivellari@suse.com> References: <20250905090953.109082-1-marco.crivellari@suse.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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_wq is a per-CPU worqueue, yet nothing in its name tells about that CPU affinity constraint, which is very often not required by users. Make it clear by adding a system_percpu_wq. queue_work() / queue_delayed_work() mod_delayed_work() will now use the new per-cpu wq: whether the user still stick on the old name a warn will be printed along a wq redirect to the new one. This patch add the new system_percpu_wq except for mm, fs and net subsystem, whom are handled in separated patches. The old wq will be kept for a few release cylces. Suggested-by: Tejun Heo Signed-off-by: Marco Crivellari --- kernel/smp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/smp.c b/kernel/smp.c index 974f3a3962e8..c3b93476d645 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -1146,7 +1146,7 @@ int smp_call_on_cpu(unsigned int cpu, int (*func)(voi= d *), void *par, bool phys) if (cpu >=3D nr_cpu_ids || !cpu_online(cpu)) return -ENXIO; =20 - 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); =20 --=20 2.51.0