Re: [PATCH] virtio: remove virtio-pci root device

Michael S. Tsirkin
2011-01-09T15:19:20Z

On Fri, Jan 07, 2011 at 02:55:06AM -0600, Milton Miller wrote:
> We sometimes need to map between the virtio device and
> the given pci device. One such use is OS installer that
> gets the boot pci device from BIOS and needs to
> find the relevant block device. Since it can't,
> installation fails.
>
> Instead of creating a top-level devices/virtio-pci
> directory, create each device under the corresponding
> pci device node. Symlinks to all virtio-pci
> devices can be found under the pci driver link in
> bus/pci/drivers/virtio-pci/devices, and all virtio
> devices under drivers/bus/virtio/devices.
>
> Signed-off-by: Milton Miller <miltonm@bga.com>

OK, this works fine for me. I played with options to add compat
softlinks under devices/virtio-pci but we still don't get exactly the
same layout and since I don't think anyone actually uses them, it's
probably ok to just to the simple thing.

Tested/Acked-by: Michael S. Tsirkin <mst@redhat.com>

Rusty, since this help fix at least one user, any chance this can be put
in 2.6.38? OK to backport to -stable?

Gleb, could you try this out too?

> ---
>
> This is an alternative to the patch by Michael S. Tsirkin
> titled "virtio-pci: add softlinks between virtio and pci"
> https://patchwork.kernel.org/patch/454581/
>
> It creates simpler code, uses less memory, and should
> be even easier use by the installer as it won't have to
> know a virtio symlink to follow (just follow none).
>
> Compile tested only as I don't have kvm setup.
>
>
> diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
> index ef8d9d5..4fb5b2b 100644
> --- a/drivers/virtio/virtio_pci.c
> +++ b/drivers/virtio/virtio_pci.c
> @@ -96,11 +96,6 @@ static struct pci_device_id virtio_pci_id_table[] = {
>
> MODULE_DEVICE_TABLE(pci, virtio_pci_id_table);
>
> -/* A PCI device has it's own struct device and so does a virtio device so
> - * we create a place for the virtio devices to show up in sysfs. I think it
> - * would make more sense for virtio to not insist on having it's own device. */
> -static struct device *virtio_pci_root;
> -
> /* Convert a generic virtio device to our structure */
> static struct virtio_pci_device *to_vp_device(struct virtio_device *vdev)
> {
> @@ -629,7 +624,7 @@ static int __devinit virtio_pci_probe(struct pci_dev *pci_dev,
> if (vp_dev == NULL)
> return -ENOMEM;
>
> - vp_dev->vdev.dev.parent = virtio_pci_root;
> + vp_dev->vdev.dev.parent = &pci_dev->dev;
> vp_dev->vdev.dev.release = virtio_pci_release_dev;
> vp_dev->vdev.config = &virtio_pci_config_ops;
> vp_dev->pci_dev = pci_dev;
> @@ -717,17 +712,7 @@ static struct pci_driver virtio_pci_driver = {
>
> static int __init virtio_pci_init(void)
> {
> - int err;
> -
> - virtio_pci_root = root_device_register("virtio-pci");
> - if (IS_ERR(virtio_pci_root))
> - return PTR_ERR(virtio_pci_root);
> -
> - err = pci_register_driver(&virtio_pci_driver);
> - if (err)
> - root_device_unregister(virtio_pci_root);
> -
> - return err;
> + return pci_register_driver(&virtio_pci_driver);
> }
>
> module_init(virtio_pci_init);
> @@ -735,7 +720,6 @@ module_init(virtio_pci_init);
> static void __exit virtio_pci_exit(void)
> {
> pci_unregister_driver(&virtio_pci_driver);
> - root_device_unregister(virtio_pci_root);
> }
>
> module_exit(virtio_pci_exit);