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rcu: replace use of system_wq with system_percpu_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_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.

The old wq will be kept for a few release cylces.

Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
Marco Crivellari 2025-09-19 16:50:37 +02:00 committed by Paul E. McKenney
parent a214365140
commit 143ddfa169
1 changed files with 2 additions and 2 deletions
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4
kernel/rcu/tasks.h
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@ -553,13 +553,13 @@ static void rcu_tasks_invoke_cbs(struct rcu_tasks *rtp, struct rcu_tasks_percpu
rtpcp_next = rtp->rtpcp_array[index]; rtpcp_next = rtp->rtpcp_array[index];
if (rtpcp_next->cpu < smp_load_acquire(&rtp->percpu_dequeue_lim)) { if (rtpcp_next->cpu < smp_load_acquire(&rtp->percpu_dequeue_lim)) {
cpuwq = rcu_cpu_beenfullyonline(rtpcp_next->cpu) ? rtpcp_next->cpu : WORK_CPU_UNBOUND; cpuwq = rcu_cpu_beenfullyonline(rtpcp_next->cpu) ? rtpcp_next->cpu : WORK_CPU_UNBOUND;
queue_work_on(cpuwq, system_wq, &rtpcp_next->rtp_work); queue_work_on(cpuwq, system_percpu_wq, &rtpcp_next->rtp_work);
index++; index++;
if (index < num_possible_cpus()) { if (index < num_possible_cpus()) {
rtpcp_next = rtp->rtpcp_array[index]; rtpcp_next = rtp->rtpcp_array[index];
if (rtpcp_next->cpu < smp_load_acquire(&rtp->percpu_dequeue_lim)) { if (rtpcp_next->cpu < smp_load_acquire(&rtp->percpu_dequeue_lim)) {
cpuwq = rcu_cpu_beenfullyonline(rtpcp_next->cpu) ? rtpcp_next->cpu : WORK_CPU_UNBOUND; cpuwq = rcu_cpu_beenfullyonline(rtpcp_next->cpu) ? rtpcp_next->cpu : WORK_CPU_UNBOUND;
queue_work_on(cpuwq, system_wq, &rtpcp_next->rtp_work); queue_work_on(cpuwq, system_percpu_wq, &rtpcp_next->rtp_work);
} }
} }
} }