workqueue: introduce system_highpri_wq

Commit 3270476a6c0ce322354df8679652f060d66526dc ('workqueue: reimplement
WQ_HIGHPRI using a separate worker_pool') introduce separate worker pool
for HIGHPRI. When we handle busyworkers for gcwq, it can be normal worker
or highpri worker. But, we don't consider this difference in rebind_workers(),
we use just system_wq for highpri worker. It makes mismatch between
cwq->pool and worker->pool.

It doesn't make error in current implementation, but possible in the future.
Now, we introduce system_highpri_wq to use proper cwq for highpri workers
in rebind_workers(). Following patch fix this issue properly.

tj: Even apart from rebinding, having system_highpri_wq generally
    makes sense.

Signed-off-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

1 files changed, 6 insertions, 3 deletions

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 99ee9b939264..329c404b68c2 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -269,12 +269,14 @@ struct workqueue_struct {
 };
 
 struct workqueue_struct *system_wq __read_mostly;
+struct workqueue_struct *system_highpri_wq __read_mostly;
 struct workqueue_struct *system_long_wq __read_mostly;
 struct workqueue_struct *system_nrt_wq __read_mostly;
 struct workqueue_struct *system_unbound_wq __read_mostly;
 struct workqueue_struct *system_freezable_wq __read_mostly;
 struct workqueue_struct *system_nrt_freezable_wq __read_mostly;
 EXPORT_SYMBOL_GPL(system_wq);
+EXPORT_SYMBOL_GPL(system_highpri_wq);
 EXPORT_SYMBOL_GPL(system_long_wq);
 EXPORT_SYMBOL_GPL(system_nrt_wq);
 EXPORT_SYMBOL_GPL(system_unbound_wq);
@@ -3928,6 +3930,7 @@ static int __init init_workqueues(void)
         }
 
         system_wq = alloc_workqueue("events", 0, 0);
+        system_highpri_wq = alloc_workqueue("events_highpri", WQ_HIGHPRI, 0);
         system_long_wq = alloc_workqueue("events_long", 0, 0);
         system_nrt_wq = alloc_workqueue("events_nrt", WQ_NON_REENTRANT, 0);
         system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND,
@@ -3936,9 +3939,9 @@ static int __init init_workqueues(void)
                                               WQ_FREEZABLE, 0);
         system_nrt_freezable_wq = alloc_workqueue("events_nrt_freezable",
                         WQ_NON_REENTRANT | WQ_FREEZABLE, 0);
-        BUG_ON(!system_wq || !system_long_wq || !system_nrt_wq ||
-               !system_unbound_wq || !system_freezable_wq ||
-                !system_nrt_freezable_wq);
+        BUG_ON(!system_wq || !system_highpri_wq || !system_long_wq ||
+               !system_nrt_wq || !system_unbound_wq || !system_freezable_wq ||
+               !system_nrt_freezable_wq);
         return 0;
 }
 early_initcall(init_workqueues);