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

From: Alexander Strakh
Date: Mon Mar 01 2010 - 10:28:14 EST


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;
...
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