linux-kernel - Re: [PATCH v2 1/1] virtio: update balloon size in balloon "probe"

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Date:   Tue, 4 Oct 2016 13:47:38 +0300
From:   Konstantin Neumoin <kneumoin@...tuozzo.com>
To:     virtualization@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org
Cc:     "Denis V. Lunev" <den@...nvz.org>,
        "Michael S . Tsirkin" <mst@...hat.com>
Subject: Re: [PATCH v2 1/1] virtio: update balloon size in balloon "probe"

ping

On 09/29/2016 01:17 PM, Denis V. Lunev wrote:
> From: Konstantin Neumoin <kneumoin@...tuozzo.com>
>
> The following commit 'fad7b7b27b6a (virtio_balloon: Use a workqueue
> instead of "vballoon" kthread)' has added a regression. Original code with
> kthread starts the thread inside probe and checks the necessity to update
> balloon inside the thread immediately.
>
> Nowadays the code behaves differently. Work is queued only on the first
> command from the host after the negotiation. Thus there is a window
> especially at the guest startup or the module reloading when the balloon
> size is not updated until the notification from the host.
>
> This patch adds balloon size check at the end of the probe to match
> original behaviour.
>
> Signed-off-by: Konstantin Neumoin <kneumoin@...tuozzo.com>
> Signed-off-by: Denis V. Lunev <den@...nvz.org>
> CC: Michael S. Tsirkin <mst@...hat.com>
> ---
>   drivers/virtio/virtio_balloon.c | 2 ++
>   1 file changed, 2 insertions(+)
>
> Changes from v1:
> - fixed description
> - removed update_balloon_size() call
>
> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
> index 4e7003d..181793f 100644
> --- a/drivers/virtio/virtio_balloon.c
> +++ b/drivers/virtio/virtio_balloon.c
> @@ -577,6 +577,8 @@ static int virtballoon_probe(struct virtio_device *vdev)
>   
>   	virtio_device_ready(vdev);
>   
> +	if (towards_target(vb))
> +		virtballoon_changed(vdev);
>   	return 0;
>   
>   out_del_vqs: