Re: [PATCH v3 06/11] virtio: blk: Add freeze, restore handlers to support S4

Michael S. Tsirkin
2011-11-17T12:27:04Z

On Thu, Nov 17, 2011 at 05:27:37PM +0530, Amit Shah wrote:
> Delete the vq and flush any pending requests from the block queue on the
> freeze callback to prepare for hibernation.
>
> Re-create the vq in the restore callback to resume normal function.
>
> Signed-off-by: Amit Shah <amit.shah@redhat.com>
> ---
> drivers/block/virtio_blk.c | 36 ++++++++++++++++++++++++++++++++++++
> 1 files changed, 36 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
> index 467f218..f73fb2d 100644
> --- a/drivers/block/virtio_blk.c
> +++ b/drivers/block/virtio_blk.c
> @@ -568,6 +568,38 @@ static void __devexit virtblk_remove(struct virtio_device *vdev)
> ida_simple_remove(&vd_index_ida, index);
> }
>
> +#ifdef CONFIG_PM
> +static int virtblk_freeze(struct virtio_device *vdev)
> +{
> + struct virtio_blk *vblk = vdev->priv;
> +
> + flush_work(&vblk->config_work);

What if a new config_work is scheduled after this point?
The right thing to do seems to be to flush after disabling interrupts.

> + spin_lock_irq(vblk->disk->queue->queue_lock);
> + blk_stop_queue(vblk->disk->queue);
> + spin_unlock_irq(vblk->disk->queue->queue_lock);
> + blk_sync_queue(vblk->disk->queue);
> +
> + /* Stop all the virtqueues. */
> + vdev->config->reset(vdev);
> + vdev->config->del_vqs(vdev);

I think del_vqs should be followed by reset:
del_vqs assumes the device in a state find put it in.

> + return 0;
> +}
> +
> +static int virtblk_restore(struct virtio_device *vdev)
> +{
> + struct virtio_blk *vblk = vdev->priv;
> + int ret;
> +
> + ret = init_vq(vdev->priv);
> + if (!ret) {
> + spin_lock_irq(vblk->disk->queue->queue_lock);
> + blk_start_queue(vblk->disk->queue);
> + spin_unlock_irq(vblk->disk->queue->queue_lock);
> + }
> + return ret;
> +}
> +#endif
> +
> static const struct virtio_device_id id_table[] = {
> { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID },
> { 0 },
> @@ -593,6 +625,10 @@ static struct virtio_driver __refdata virtio_blk = {
> .probe = virtblk_probe,
> .remove = __devexit_p(virtblk_remove),
> .config_changed = virtblk_config_changed,
> +#ifdef CONFIG_PM
> + .freeze = virtblk_freeze,
> + .restore = virtblk_restore,
> +#endif
> };
>
> static int __init init(void)
> --
> 1.7.7.1