workqueue: introduce for_each_pool()

With the scheduled unbound pools with custom attributes, there will be
multiple unbound pools, so it wouldn't be able to use
for_each_wq_cpu() + for_each_std_worker_pool() to iterate through all
pools.

Introduce for_each_pool() which iterates through all pools using
worker_pool_idr and use it instead of for_each_wq_cpu() +
for_each_std_worker_pool() combination in freeze_workqueues_begin().

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>

1 files changed, 21 insertions, 15 deletions

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 2db1532b09dc..55494e3f9f3b 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -295,6 +295,14 @@ static inline int __next_wq_cpu(int cpu, const struct cpumask *mask,
              (cpu) = __next_wq_cpu((cpu), cpu_online_mask, 3))
 
 /**
+ * for_each_pool - iterate through all worker_pools in the system
+ * @pool: iteration cursor
+ * @id: integer used for iteration
+ */
+#define for_each_pool(pool, id)                                         \
+        idr_for_each_entry(&worker_pool_idr, pool, id)
+
+/**
  * for_each_pwq - iterate through all pool_workqueues of the specified workqueue
  * @pwq: iteration cursor
  * @wq: the target workqueue
@@ -3586,33 +3594,31 @@ EXPORT_SYMBOL_GPL(work_on_cpu);
  */
 void freeze_workqueues_begin(void)
 {
-        unsigned int cpu;
+        struct worker_pool *pool;
+        int id;
 
         spin_lock_irq(&workqueue_lock);
 
         WARN_ON_ONCE(workqueue_freezing);
         workqueue_freezing = true;
 
-        for_each_wq_cpu(cpu) {
-                struct worker_pool *pool;
+        for_each_pool(pool, id) {
                 struct workqueue_struct *wq;
 
-                for_each_std_worker_pool(pool, cpu) {
-                        spin_lock(&pool->lock);
-
-                        WARN_ON_ONCE(pool->flags & POOL_FREEZING);
-                        pool->flags |= POOL_FREEZING;
+                spin_lock(&pool->lock);
 
-                        list_for_each_entry(wq, &workqueues, list) {
-                                struct pool_workqueue *pwq = get_pwq(cpu, wq);
+                WARN_ON_ONCE(pool->flags & POOL_FREEZING);
+                pool->flags |= POOL_FREEZING;
 
-                                if (pwq && pwq->pool == pool &&
-                                    (wq->flags & WQ_FREEZABLE))
-                                        pwq->max_active = 0;
-                        }
+                list_for_each_entry(wq, &workqueues, list) {
+                        struct pool_workqueue *pwq = get_pwq(pool->cpu, wq);
 
-                        spin_unlock(&pool->lock);
+                        if (pwq && pwq->pool == pool &&
+                            (wq->flags & WQ_FREEZABLE))
+                                pwq->max_active = 0;
                 }
+
+                spin_unlock(&pool->lock);
         }
 
         spin_unlock_irq(&workqueue_lock);