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Commit 0909dc44 authored by NeilBrown's avatar NeilBrown
Browse files

md: tidy up error paths in md_alloc 



As the recent bug in md_alloc showed, having a single exit path for
unlocking and putting is a good idea.  So restructure md_alloc to have
a single mutex_unlock and mddev_put, and use gotos where necessary.

Found-by: default avatarJiri Slaby <jirislaby@gmail.com>
Signed-off-by: default avatarNeilBrown <neilb@suse.de>
parent 1ec22eb2

drivers/md/md.c

+18 −20
Original line number Diff line number Diff line
@@ -3846,11 +3846,9 @@ static int md_alloc(dev_t dev, char *name) 
	flush_scheduled_work();



	mutex_lock(&disks_mutex);

	if (mddev->gendisk) {

		mutex_unlock(&disks_mutex);

		mddev_put(mddev);

		return -EEXIST;

	}

	error = -EEXIST;

	if (mddev->gendisk)

		goto abort;



	if (name) {

		/* Need to ensure that 'name' is not a duplicate.
@@ -3862,19 +3860,15 @@ static int md_alloc(dev_t dev, char *name) 
			if (mddev2->gendisk &&

			    strcmp(mddev2->gendisk->disk_name, name) == 0) {

				spin_unlock(&all_mddevs_lock);

				mutex_unlock(&disks_mutex);

				mddev_put(mddev);

				return -EEXIST;

				goto abort;

			}

		spin_unlock(&all_mddevs_lock);

	}



	error = -ENOMEM;

	mddev->queue = blk_alloc_queue(GFP_KERNEL);

	if (!mddev->queue) {

		mutex_unlock(&disks_mutex);

		mddev_put(mddev);

		return -ENOMEM;

	}

	if (!mddev->queue)

		goto abort;

	mddev->queue->queuedata = mddev;



	/* Can be unlocked because the queue is new: no concurrency */
@@ -3884,11 +3878,9 @@ static int md_alloc(dev_t dev, char *name) 


	disk = alloc_disk(1 << shift);

	if (!disk) {

		mutex_unlock(&disks_mutex);

		blk_cleanup_queue(mddev->queue);

		mddev->queue = NULL;

		mddev_put(mddev);

		return -ENOMEM;

		goto abort;

	}

	disk->major = MAJOR(mddev->unit);

	disk->first_minor = unit << shift;
@@ -3910,16 +3902,22 @@ static int md_alloc(dev_t dev, char *name) 
	mddev->gendisk = disk;

	error = kobject_init_and_add(&mddev->kobj, &md_ktype,

				     &disk_to_dev(disk)->kobj, "%s", "md");

	mutex_unlock(&disks_mutex);

	if (error)

	if (error) {

		/* This isn't possible, but as kobject_init_and_add is marked

		 * __must_check, we must do something with the result

		 */

		printk(KERN_WARNING "md: cannot register %s/md - name in use\n",

		       disk->disk_name);

	else {

		error = 0;

	}

 abort:

	mutex_unlock(&disks_mutex);

	if (!error) {

		kobject_uevent(&mddev->kobj, KOBJ_ADD);

		mddev->sysfs_state = sysfs_get_dirent(mddev->kobj.sd, "array_state");

	}

	mddev_put(mddev);

	return 0;

	return error;

}



static struct kobject *md_probe(dev_t dev, int *part, void *data)