block: Complain if queue_flag_(set|clear)_unlocked() is abused

Since it is not safe to use queue_flag_(set|clear)_unlocked()
without holding the queue lock after the sysfs entries for a
queue have been created, complain if this happens.

Cc: Mike Snitzer <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Hannes Reinecke <[email protected]>
Cc: Ming Lei <[email protected]>
Reviewed-by: Johannes Thumshirn <[email protected]>
Reviewed-by: Martin K. Petersen <[email protected]>
Signed-off-by: Bart Van Assche <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>

Author: KAGA-KOKO

include/linux/blkdev.h

@@ -728,12 +728,18 @@ static inline void queue_lockdep_assert_held(struct request_queue *q)
 static inline void queue_flag_set_unlocked(unsigned int flag,
 					   struct request_queue *q)
 {
+	if (test_bit(QUEUE_FLAG_INIT_DONE, &q->queue_flags) &&
+	    kref_read(&q->kobj.kref))
+		lockdep_assert_held(q->queue_lock);
 	__set_bit(flag, &q->queue_flags);
 }
 
 static inline void queue_flag_clear_unlocked(unsigned int flag,
 					     struct request_queue *q)
 {
+	if (test_bit(QUEUE_FLAG_INIT_DONE, &q->queue_flags) &&
+	    kref_read(&q->kobj.kref))
+		lockdep_assert_held(q->queue_lock);
 	__clear_bit(flag, &q->queue_flags);
 }