Commit c2a57380 authored by Marco Crivellari's avatar Marco Crivellari Committed by Peter Zijlstra
Browse files

sched: Replace use of system_unbound_wq with system_dfl_wq 



Currently if a user enqueues 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 consistency cannot be addressed without refactoring the API.
For more details see the Link tag below.

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

commit 128ea9f6 ("workqueue: Add system_percpu_wq and system_dfl_wq")
commit 930c2ea5 ("workqueue: Add new WQ_PERCPU flag")

Switch to using system_dfl_wq because system_unbound_wq is going away as part of
a workqueue restructuring.

Suggested-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarMarco Crivellari <marco.crivellari@suse.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/20250221112003.1dSuoGyc@linutronix.de/
Link: https://patch.msgid.link/20251107092452.43399-1-marco.crivellari@suse.com
parent c0e1832b

kernel/sched/core.c

+2 −2
Original line number Diff line number Diff line
@@ -5678,7 +5678,7 @@ static void sched_tick_remote(struct work_struct *work) 
	os = atomic_fetch_add_unless(&twork->state, -1, TICK_SCHED_REMOTE_RUNNING);

	WARN_ON_ONCE(os == TICK_SCHED_REMOTE_OFFLINE);

	if (os == TICK_SCHED_REMOTE_RUNNING)

		queue_delayed_work(system_unbound_wq, dwork, HZ);

		queue_delayed_work(system_dfl_wq, dwork, HZ);

}



static void sched_tick_start(int cpu)
@@ -5697,7 +5697,7 @@ static void sched_tick_start(int cpu) 
	if (os == TICK_SCHED_REMOTE_OFFLINE) {

		twork->cpu = cpu;

		INIT_DELAYED_WORK(&twork->work, sched_tick_remote);

		queue_delayed_work(system_unbound_wq, &twork->work, HZ);

		queue_delayed_work(system_dfl_wq, &twork->work, HZ);

	}

}

kernel/sched/ext.c

+2 −2
Original line number Diff line number Diff line
@@ -2762,7 +2762,7 @@ static void scx_watchdog_workfn(struct work_struct *work) 


		cond_resched();

	}

	queue_delayed_work(system_unbound_wq, to_delayed_work(work),

	queue_delayed_work(system_dfl_wq, to_delayed_work(work),

			   scx_watchdog_timeout / 2);

}
@@ -5059,7 +5059,7 @@ static int scx_enable(struct sched_ext_ops *ops, struct bpf_link *link) 


	WRITE_ONCE(scx_watchdog_timeout, timeout);

	WRITE_ONCE(scx_watchdog_timestamp, jiffies);

	queue_delayed_work(system_unbound_wq, &scx_watchdog_work,

	queue_delayed_work(system_dfl_wq, &scx_watchdog_work,

			   scx_watchdog_timeout / 2);



	/*