Re: [PATCH v3 11/11] virtio: balloon: Add freeze, restore handlers to support S4
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2011-11-17 12:23:44
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On Thu, Nov 17, 2011 at 05:27:42PM +0530, Amit Shah wrote:
quoted hunk ↗ jump to hunk
Delete the vqs on the freeze callback to prepare for hibernation. Re-create the vqs in the restore callback to resume normal function. Signed-off-by: Amit Shah <redacted> --- drivers/virtio/virtio_balloon.c | 20 ++++++++++++++++++++ 1 files changed, 20 insertions(+), 0 deletions(-)diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index 1ff3cf4..90149d1 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c@@ -363,6 +363,22 @@ static void __devexit virtballoon_remove(struct virtio_device *vdev) kfree(vb); } +#ifdef CONFIG_PM +static int virtballoon_freeze(struct virtio_device *vdev) +{ + /* Now we reset the device so we can clean up the queues. */ + vdev->config->reset(vdev); +
This is a weird thing to do. We normally delete vqs then reset. For example, I don't know whether we guarantee what happens to MSI-X vectors assigned meanwhile if you reset. IIRC qemu doesn't use MSI-X for the balloon, but nothing prevents it.
+ vdev->config->del_vqs(vdev);
What prevents requests being submitted at this point? I see all kind of handling of freezing in the balloon thread ... maybe that gives us some guarantees, but if yes it makes sense to add a comment to point this out.
quoted hunk ↗ jump to hunk
+ return 0; +} + +static int virtballoon_restore(struct virtio_device *vdev) +{ + return init_vqs(vdev->priv); +} +#endif + static unsigned int features[] = { VIRTIO_BALLOON_F_MUST_TELL_HOST, VIRTIO_BALLOON_F_STATS_VQ,@@ -377,6 +393,10 @@ static struct virtio_driver virtio_balloon_driver = { .probe = virtballoon_probe, .remove = __devexit_p(virtballoon_remove), .config_changed = virtballoon_changed, +#ifdef CONFIG_PM + .freeze = virtballoon_freeze, + .restore = virtballoon_restore, +#endif }; static int __init init(void)-- 1.7.7.1