ublk_drv: check ubq_daemon_is_dying() in __ublk_rq_task_work()

Replace direct check on PF_EXITING in __ublk_rq_task_work() by the
existing wrapper. Also inline ubq_daemon_is_dying().

Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: ZiyangZhang <ZiyangZhang@linux.alibaba.com>
Link: https://lore.kernel.org/r/20220815023633.259825-2-ZiyangZhang@linux.alibaba.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/ublk_drv.c

@@ -555,7 +555,7 @@ static inline struct ublk_uring_cmd_pdu *ublk_get_uring_cmd_pdu(
 	return (struct ublk_uring_cmd_pdu *)&ioucmd->pdu;
 }
 
-static bool ubq_daemon_is_dying(struct ublk_queue *ubq)
+static inline bool ubq_daemon_is_dying(struct ublk_queue *ubq)
 {
 	return ubq->ubq_daemon->flags & PF_EXITING;
 }
@@ -644,8 +644,7 @@ static inline void __ublk_rq_task_work(struct request *req)
 	struct ublk_device *ub = ubq->dev;
 	int tag = req->tag;
 	struct ublk_io *io = &ubq->ios[tag];
-	bool task_exiting = current != ubq->ubq_daemon ||
-		(current->flags & PF_EXITING);
+	bool task_exiting = current != ubq->ubq_daemon || ubq_daemon_is_dying(ubq);
 	unsigned int mapped_bytes;
 
 	pr_devel("%s: complete: op %d, qid %d tag %d io_flags %x addr %llx\n",