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

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Message-Id: <201003011827.41818.strakh@ispras.ru>
Date:	Mon, 1 Mar 2010 18:27:41 +0000
From:	Alexander Strakh <strakh@...ras.ru>
To:	Drew Eckhardt <drew@...orado.edu>,
	Thomas Quinot <thomas@...chior.cuivre.fdn.fr>,
	Gerd Knorr <kraxel@...tu-berlin.de>,
	Jens Axboe <axboe@...e.de>,
	Richard Gooch <rgooch@...f.csiro.au>,
	Arnaldo Carvalho de Melo <acme@...ectiva.com.br>,
	linux-scsi@...r.kernel.org, Jens Axboe <axboe@...nel.dk>,
	linux-kernel@...r.kernel.org
Cc:	Eric Youngdale <ericy@...ante.org>
Subject: 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;
...
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