question about del_gendisk function use in drivers/scsi/sr.c

KERNEL_VERSION: 2.6.33
SUBJECT: question about del_gendisk function use SUBSCRIBE:
In driver drivers/scsi/sr.c in function sr_probe:

1. In line 588 we call alloc_disk(1);
2. If in line 593 function find_first_zero_bit returns SR_DISKS then we goto label fail_put (line 597).
3. In line 652 we call put_disk. But in some other drivers del_gendisk is called before put_disk. Why didn't we call del_gendisk before put_disk here? Is it an error?

570 static int sr_probe(struct device *dev)
571 {

572         struct scsi_device *sdev = to_scsi_device(dev);
573         struct gendisk *disk;
574         struct scsi_cd *cd;
575         int minor, error;

576
577 error = -ENODEV;
578 if (sdev->type != TYPE_ROM && sdev->type != TYPE_WORM)
579 goto fail;
580

581         error = -ENOMEM;
582         cd = kzalloc(sizeof(*cd), GFP_KERNEL);
583         if (!cd)

584 goto fail;
585
586 kref_init(&cd->kref);
587
588 disk = alloc_disk(1);
589 if (!disk)
590 goto fail_free;
591

592         spin_lock(&sr_index_lock);
593         minor = find_first_zero_bit(sr_index_bits, SR_DISKS);
594         if (minor == SR_DISKS) {
595                 spin_unlock(&sr_index_lock);
596                 error = -EBUSY;
597                 goto fail_put;

598 }

...
641 goto fail_put;
642

643         dev_set_drvdata(dev, cd);
644         disk->flags |= GENHD_FL_REMOVABLE;
645         add_disk(disk);

646
647 sdev_printk(KERN_DEBUG, sdev,
648 "Attached scsi CD-ROM %s\n", cd->cdi.name);
649 return 0;
650
651 fail_put:
652 put_disk(disk);
653 fail_free:
654 kfree(cd);
655 fail:
656 return error;
...