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Date: Thu, 10 Mar 2016 09:09:41 +0100
From: Christoph Hellwig <hch@lst.de>
To: Dan Williams <dan.j.williams@intel.com>
Cc: axboe@fb.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
        viro@zeniv.linux.org.uk
Subject: Re: [PATCH 1/3] block: introduce device_add_disk()
Message-ID: <20160310080940.GA773@lst.de>
References: <20160225200018.21975.30922.stgit@dwillia2-desk3.amr.corp.intel.com> <20160225200443.21975.77561.stgit@dwillia2-desk3.amr.corp.intel.com>
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>  /**
> - * add_disk - add partitioning information to kernel list
> + * device_add_disk - add partitioning information to kernel list
> + * @parent: parent device for the disk
>   * @disk: per-device partitioning information
>   *
>   * This function registers the partitioning information in @disk
> @@ -581,7 +582,7 @@ exit:
>   *
>   * FIXME: error handling
>   */
> -void add_disk(struct gendisk *disk)
> +int device_add_disk(struct device *parent, struct gendisk *disk)
>  {
>  	struct backing_dev_info *bdi;
>  	dev_t devt;
> @@ -597,10 +598,8 @@ void add_disk(struct gendisk *disk)
>  	disk->flags |= GENHD_FL_UP;
>  
>  	retval = blk_alloc_devt(&disk->part0, &devt);
> -	if (retval) {
> -		WARN_ON(1);
> -		return;
> -	}
> +	if (retval)
> +		return retval;
>  	disk_to_dev(disk)->devt = devt;
>  
>  	/* ->major and ->first_minor aren't supposed to be
> @@ -617,7 +616,7 @@ void add_disk(struct gendisk *disk)
>  
>  	blk_register_region(disk_devt(disk), disk->minors, NULL,
>  			    exact_match, exact_lock, disk);
> -	register_disk(disk);
> +	register_disk(parent, disk);
>  	blk_register_queue(disk);
>  
>  	/*
> @@ -628,12 +627,11 @@ void add_disk(struct gendisk *disk)
>  
>  	retval = sysfs_create_link(&disk_to_dev(disk)->kobj, &bdi->dev->kobj,
>  				   "bdi");
> -	WARN_ON(retval);
> -
>  	disk_add_events(disk);
>  	blk_integrity_add(disk);
> +	return retval;

How are the callers expected to unwind after already having added the
disk?