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workqueue: replace use of system_wq with system_percpu_wq

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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 <tj@kernel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Marco Crivellari 2025-09-05 11:13:24 +02:00 committed by Tejun Heo
parent f6cfa602d2
commit a2be943b46
2 changed files with 12 additions and 12 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

22
include/linux/workqueue.h
View file

@ -434,10 +434,10 @@ enum wq_consts {
* short queue flush time. Don't queue works which can run for too
* long.
*
* system_highpri_wq is similar to system_wq but for work items which
* system_highpri_wq is similar to system_percpu_wq but for work items which
* require WQ_HIGHPRI.
*
* system_long_wq is similar to system_wq but may host long running
* system_long_wq is similar to system_percpu_wq but may host long running
* works. Queue flushing might take relatively long.
*
* system_dfl_wq is unbound workqueue. Workers are not bound to
@ -445,13 +445,13 @@ enum wq_consts {
* executed immediately as long as max_active limit is not reached and
* resources are available.
*
* system_freezable_wq is equivalent to system_wq except that it's
* system_freezable_wq is equivalent to system_percpu_wq except that it's
* freezable.
*
* *_power_efficient_wq are inclined towards saving power and converted
* into WQ_UNBOUND variants if 'wq_power_efficient' is enabled; otherwise,
* they are same as their non-power-efficient counterparts - e.g.
* system_power_efficient_wq is identical to system_wq if
* system_power_efficient_wq is identical to system_percpu_wq if
* 'wq_power_efficient' is disabled. See WQ_POWER_EFFICIENT for more info.
*
* system_bh[_highpri]_wq are convenience interface to softirq. BH work items
@ -708,7 +708,7 @@ static inline bool mod_delayed_work(struct workqueue_struct *wq,
*/
static inline bool schedule_work_on(int cpu, struct work_struct *work)
{
return queue_work_on(cpu, system_wq, work);
return queue_work_on(cpu, system_percpu_wq, work);
}
/**
@ -727,7 +727,7 @@ static inline bool schedule_work_on(int cpu, struct work_struct *work)
*/
static inline bool schedule_work(struct work_struct *work)
{
return queue_work(system_wq, work);
return queue_work(system_percpu_wq, work);
}
/**
@ -770,15 +770,15 @@ extern void __warn_flushing_systemwide_wq(void)
#define flush_scheduled_work() \
({ \
__warn_flushing_systemwide_wq(); \
__flush_workqueue(system_wq); \
__flush_workqueue(system_percpu_wq); \
})
#define flush_workqueue(wq) \
({ \
struct workqueue_struct *_wq = (wq); \
\
if ((__builtin_constant_p(_wq == system_wq) && \
_wq == system_wq) || \
if ((__builtin_constant_p(_wq == system_percpu_wq) && \
_wq == system_percpu_wq) || \
(__builtin_constant_p(_wq == system_highpri_wq) && \
_wq == system_highpri_wq) || \
(__builtin_constant_p(_wq == system_long_wq) && \
@ -807,7 +807,7 @@ extern void __warn_flushing_systemwide_wq(void)
static inline bool schedule_delayed_work_on(int cpu, struct delayed_work *dwork,
unsigned long delay)
{
return queue_delayed_work_on(cpu, system_wq, dwork, delay);
return queue_delayed_work_on(cpu, system_percpu_wq, dwork, delay);
}
/**
@ -821,7 +821,7 @@ static inline bool schedule_delayed_work_on(int cpu, struct delayed_work *dwork,
static inline bool schedule_delayed_work(struct delayed_work *dwork,
unsigned long delay)
{
return queue_delayed_work(system_wq, dwork, delay);
return queue_delayed_work(system_percpu_wq, dwork, delay);
}
#ifndef CONFIG_SMP

2
kernel/workqueue.c
View file

@ -7668,7 +7668,7 @@ static int wq_watchdog_param_set_thresh(const char *val,
if (ret)
return ret;
if (system_wq)
if (system_percpu_wq)
wq_watchdog_set_thresh(thresh);
else
wq_watchdog_thresh = thresh;