workqueue: remove worker_pool->gcwq

The only remaining user of pool->gcwq is std_worker_pool_pri().
Reimplement it using get_gcwq() and remove worker_pool->gcwq.

This is part of an effort to remove global_cwq and make worker_pool
the top level abstraction, which in turn will help implementing worker
pools with user-specified attributes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>

kernel/workqueue.c

@@ -123,7 +123,6 @@ enum {
 /* struct worker is defined in workqueue_internal.h */
 
 struct worker_pool {
-	struct global_cwq	*gcwq;		/* I: the owning gcwq */
 	spinlock_t		lock;		/* the pool lock */
 	unsigned int		cpu;		/* I: the associated cpu */
 	int			id;		/* I: pool ID */
@@ -451,11 +450,6 @@ static DEFINE_IDR(worker_pool_idr);
 
 static int worker_thread(void *__worker);
 
-static int std_worker_pool_pri(struct worker_pool *pool)
-{
-	return pool - pool->gcwq->pools;
-}
-
 static struct global_cwq *get_gcwq(unsigned int cpu)
 {
 	if (cpu != WORK_CPU_UNBOUND)
@@ -464,6 +458,11 @@ static struct global_cwq *get_gcwq(unsigned int cpu)
 		return &unbound_global_cwq;
 }
 
+static int std_worker_pool_pri(struct worker_pool *pool)
+{
+	return pool - get_gcwq(pool->cpu)->pools;
+}
+
 /* allocate ID and assign it to @pool */
 static int worker_pool_assign_id(struct worker_pool *pool)
 {
@@ -3818,7 +3817,6 @@ static int __init init_workqueues(void)
 		struct worker_pool *pool;
 
 		for_each_std_worker_pool(pool, cpu) {
-			pool->gcwq = get_gcwq(cpu);
 			spin_lock_init(&pool->lock);
 			pool->cpu = cpu;
 			pool->flags |= POOL_DISASSOCIATED;