Re: [PATCH 09/15] virtio-blk: Pass attribute group to device_add_disk

Michael S. Tsirkin
2016-09-04T04:18:22Z

On Wed, Aug 17, 2016 at 03:15:09PM +0800, Fam Zheng wrote:
> Previously after device_add_disk returns, the KOBJ_ADD uevent is already
> emitted. Adding attributes after that is a poor usage of kobject, and
> in practice may result in race conditions with userspace, for
> example udev checks availability of certain attributes and initializes
> /dev entries conditionally.
>
> device_add_disk can handle adding attribute group better, so use it.
>
> Meanwhile, handle error of device_add_disk.
>
> Signed-off-by: Fam Zheng <famz@redhat.com>

Feel free to merge this with the rest of patchset
Acked-by: Michael S. Tsirkin <mst@redhat.com>

> ---
> drivers/block/virtio_blk.c | 38 +++++++++++++++++++++++++++-----------
> 1 file changed, 27 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
> index 4564df5..ff60d82 100644
> --- a/drivers/block/virtio_blk.c
> +++ b/drivers/block/virtio_blk.c
> @@ -522,10 +522,10 @@ virtblk_cache_type_show(struct device *dev, struct device_attribute *attr,
> return snprintf(buf, 40, "%s\n", virtblk_cache_types[writeback]);
> }
>
> -static const struct device_attribute dev_attr_cache_type_ro =
> +static struct device_attribute dev_attr_cache_type_ro =
> __ATTR(cache_type, S_IRUGO,
> virtblk_cache_type_show, NULL);
> -static const struct device_attribute dev_attr_cache_type_rw =
> +static struct device_attribute dev_attr_cache_type_rw =
> __ATTR(cache_type, S_IRUGO|S_IWUSR,
> virtblk_cache_type_show, virtblk_cache_type_store);
>
> @@ -550,6 +550,26 @@ static struct blk_mq_ops virtio_mq_ops = {
> static unsigned int virtblk_queue_depth;
> module_param_named(queue_depth, virtblk_queue_depth, uint, 0444);
>
> +static struct attribute *virtblk_attrs_ro[] = {
> + &dev_attr_serial.attr,
> + &dev_attr_cache_type_ro.attr,
> + NULL
> +};
> +
> +static struct attribute *virtblk_attrs_rw[] = {
> + &dev_attr_serial.attr,
> + &dev_attr_cache_type_rw.attr,
> + NULL
> +};
> +
> +static struct attribute_group virtblk_attr_group_ro = {
> + .attrs = virtblk_attrs_ro,
> +};
> +
> +static struct attribute_group virtblk_attr_group_rw = {
> + .attrs = virtblk_attrs_rw,
> +};
> +
> static int virtblk_probe(struct virtio_device *vdev)
> {
> struct virtio_blk *vblk;
> @@ -560,6 +580,7 @@ static int virtblk_probe(struct virtio_device *vdev)
> u32 v, blk_size, sg_elems, opt_io_size;
> u16 min_io_size;
> u8 physical_block_exp, alignment_offset;
> + struct attribute_group *attr_group;
>
> if (!vdev->config->get) {
> dev_err(&vdev->dev, "%s failure: config access disabled\n",
> @@ -719,19 +740,14 @@ static int virtblk_probe(struct virtio_device *vdev)
>
> virtio_device_ready(vdev);
>
> - device_add_disk(&vdev->dev, vblk->disk, NULL);
> - err = device_create_file(disk_to_dev(vblk->disk), &dev_attr_serial);
> - if (err)
> - goto out_del_disk;
> -
> if (virtio_has_feature(vdev, VIRTIO_BLK_F_CONFIG_WCE))
> - err = device_create_file(disk_to_dev(vblk->disk),
> - &dev_attr_cache_type_rw);
> + attr_group = &virtblk_attr_group_rw;
> else
> - err = device_create_file(disk_to_dev(vblk->disk),
> - &dev_attr_cache_type_ro);
> + attr_group = &virtblk_attr_group_ro;
> + err = device_add_disk(&vdev->dev, vblk->disk, attr_group);
> if (err)
> goto out_del_disk;
> +
> return 0;
>
> out_del_disk:
> --
> 2.7.4