struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag)
{
	return tags->rqs[tag];
}
The program contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently.