Revert "block: fix null-deref in percpu_ref_put"

hulk inclusion
category: bugfix
bugzilla: 187268, https://gitee.com/openeuler/kernel/issues/I5N162

----------------------------------------

This reverts commit 51e35e67.

There is a new fix for this problem in the mainline patch, so the patch
should return to the mainline solution.

mainline patch:
d36a9ea5 ("block: fix use-after-free of q->q_usage_counter")

Fixes: 51e35e67("block: fix null-deref in percpu_ref_put")
Signed-off-by: NZhong Jinghua <zhongjinghua@huawei.com>
Reviewed-by: NHou Tao <houtao1@huawei.com>
Signed-off-by: NJialin Zhang <zhangjialin11@huawei.com>

block/blk-core.c

@@ -400,8 +400,7 @@ void blk_cleanup_queue(struct request_queue *q)
 	 * prevent that blk_mq_run_hw_queues() accesses the hardware queues
 	 * after draining finished.
 	 */
-	blk_freeze_queue_start(q);
-	blk_mq_freeze_queue_wait_sync(q);
+	blk_freeze_queue(q);
 
 	rq_qos_exit(q);
 
@@ -518,7 +517,6 @@ static void blk_queue_usage_counter_release(struct percpu_ref *ref)
 	struct request_queue *q =
 		container_of(ref, struct request_queue, q_usage_counter);
 
-	blk_queue_flag_set(QUEUE_FLAG_USAGE_COUNT_SYNC, q);
 	wake_up_all(&q->mq_freeze_wq);
 }
 

block/blk-mq.c

@@ -195,7 +195,6 @@ void blk_freeze_queue_start(struct request_queue *q)
 {
 	mutex_lock(&q->mq_freeze_lock);
 	if (++q->mq_freeze_depth == 1) {
-		blk_queue_flag_clear(QUEUE_FLAG_USAGE_COUNT_SYNC, q);
 		percpu_ref_kill(&q->q_usage_counter);
 		mutex_unlock(&q->mq_freeze_lock);
 		if (queue_is_mq(q))
@@ -206,12 +205,6 @@ void blk_freeze_queue_start(struct request_queue *q)
 }
 EXPORT_SYMBOL_GPL(blk_freeze_queue_start);
 
-void blk_mq_freeze_queue_wait_sync(struct request_queue *q)
-{
-	wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->q_usage_counter) &&
-			test_bit(QUEUE_FLAG_USAGE_COUNT_SYNC, &q->queue_flags));
-}
-
 void blk_mq_freeze_queue_wait(struct request_queue *q)
 {
 	wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->q_usage_counter));

include/linux/blk-mq.h

@@ -566,7 +566,6 @@ void blk_mq_freeze_queue(struct request_queue *q);
 void blk_mq_unfreeze_queue(struct request_queue *q);
 void blk_freeze_queue_start(struct request_queue *q);
 void blk_mq_freeze_queue_wait(struct request_queue *q);
-void blk_mq_freeze_queue_wait_sync(struct request_queue *q);
 int blk_mq_freeze_queue_wait_timeout(struct request_queue *q,
 				     unsigned long timeout);
 

include/linux/blkdev.h

@@ -643,8 +643,6 @@ struct request_queue {
 #define QUEUE_FLAG_NOWAIT       29	/* device supports NOWAIT */
 /*at least one blk-mq hctx can't get driver tag */
 #define QUEUE_FLAG_HCTX_WAIT	30
-/* sync for q_usage_counter */
-#define QUEUE_FLAG_USAGE_COUNT_SYNC    31
 
 #define QUEUE_FLAG_MQ_DEFAULT	((1 << QUEUE_FLAG_IO_STAT) |		\
 				 (1 << QUEUE_FLAG_SAME_COMP) |		\