workqueue: replace use of system_unbound_wq with system_dfl_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_unbound_wq should be the default workqueue so as not to enforce
locality constraints for random work whenever it's not required.

Adding system_dfl_wq to encourage its use when unbound work should be used.

queue_work() / queue_delayed_work() / mod_delayed_work() will now use the
new unbound wq: whether the user still use the old wq a warn will be
printed along with a wq redirect to the new one.

The old system_unbound_wq will be kept for a few release cycles.

Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 45d5dd470ff609a95dc9f54d2eaa93b7c003d7e8..af860e8f848145810e376fd56e86cc9351afdbec 100644 (file)
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -783,8 +783,8 @@ extern void __warn_flushing_systemwide_wq(void)
             _wq == system_highpri_wq) ||                               \
            (__builtin_constant_p(_wq == system_long_wq) &&             \
             _wq == system_long_wq) ||                                  \
-           (__builtin_constant_p(_wq == system_unbound_wq) &&          \
-            _wq == system_unbound_wq) ||                               \
+           (__builtin_constant_p(_wq == system_dfl_wq) &&              \
+            _wq == system_dfl_wq) ||                           \
            (__builtin_constant_p(_wq == system_freezable_wq) &&        \
             _wq == system_freezable_wq) ||                             \
            (__builtin_constant_p(_wq == system_power_efficient_wq) &&  \

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 59faf857ee4f5af42402fad49f4a885d30d80bde..2888f4399acdbdd36edc9a76e859aa9c6591ae77 100644 (file)
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -2932,7 +2932,7 @@ static void idle_worker_timeout(struct timer_list *t)
        raw_spin_unlock_irq(&pool->lock);
 
        if (do_cull)
-               queue_work(system_unbound_wq, &pool->idle_cull_work);
+               queue_work(system_dfl_wq, &pool->idle_cull_work);
 }
 
 /**