blk_stat_add_callback 3348 block/blk-mq.c 	blk_stat_add_callback(q, q->poll_cb);
blk_stat_add_callback   98 block/blk-stat.h void blk_stat_add_callback(struct request_queue *q,
blk_stat_add_callback  852 block/blk-wbt.c 	blk_stat_add_callback(q, rwb->cb);