Re: [PATCH 06/15] genhd: Add return code to device_add_disk

Cornelia Huck
2016-08-17T08:49:46Z

On Wed, 17 Aug 2016 15:15:06 +0800
Fam Zheng <famz@redhat.com> wrote:

> @@ -613,10 +614,8 @@ void device_add_disk(struct device *parent, struct gendisk *disk)
> disk->flags |= GENHD_FL_UP;
>
> retval = blk_alloc_devt(&disk->part0, &devt);
> - if (retval) {
> - WARN_ON(1);
> - return;
> - }
> + if (retval)
> + goto fail;
> disk_to_dev(disk)->devt = devt;
>
> /* ->major and ->first_minor aren't supposed to be
> @@ -625,16 +624,26 @@ void device_add_disk(struct device *parent, struct gendisk *disk)
> disk->major = MAJOR(devt);
> disk->first_minor = MINOR(devt);
>
> - disk_alloc_events(disk);
> + retval = disk_alloc_events(disk);
> + if (retval)
> + goto fail;
>
> /* Register BDI before referencing it from bdev */
> bdi = &disk->queue->backing_dev_info;
> - bdi_register_owner(bdi, disk_to_dev(disk));
> + retval = bdi_register_owner(bdi, disk_to_dev(disk));
> + if (retval)
> + goto fail;
>
> - blk_register_region(disk_devt(disk), disk->minors, NULL,
> - exact_match, exact_lock, disk);
> - register_disk(parent, disk);
> - blk_register_queue(disk);
> + retval = blk_register_region(disk_devt(disk), disk->minors, NULL,
> + exact_match, exact_lock, disk);
> + if (retval)
> + goto fail;
> + retval = register_disk(parent, disk);
> + if (retval)
> + goto fail;
> + retval = blk_register_queue(disk);
> + if (retval)
> + goto fail;
>
> /*
> * Take an extra ref on queue which will be put on disk_release()
> @@ -644,10 +653,20 @@ void device_add_disk(struct device *parent, struct gendisk *disk)
>
> retval = sysfs_create_link(&disk_to_dev(disk)->kobj, &bdi->dev->kobj,
> "bdi");
> + if (retval)
> + goto fail;
> +
> + retval = disk_add_events(disk);
> + if (retval)
> + goto fail;
> +
> + retval = blk_integrity_add(disk);
> + if (retval)
> + goto fail;
> + return 0;
> +fail:
> WARN_ON(retval);
> -
> - disk_add_events(disk);
> - blk_integrity_add(disk);
> + return retval;
> }

Noticed this when trying to figure out whether the error handling in
virtio_blk was correct:

Shouldn't you try to cleanup/rewind so that any structures are in a
sane state after failure? The caller doesn't know where device_add_disk
failed, and calling del_gendisk unconditionally like virtio_blk does is
probably not the right thing to do (at the very least, I don't think
unregistering a device that has not been registered is likely to work).