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Date: Wed, 14 Jul 2010 10:39:51 -0400 (EDT)
From: Alon Levy <alevy@redhat.com>
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In-Reply-To: <1c5b20f693ebc3882d01d8f2f9e807878251cd42.1277976486.git.amit.shah@redhat.com>
Subject: Re: [Qemu-devel] [PATCH 1/2] virtio-serial: Check if virtio queue
	is ready before consuming data
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To: Amit Shah <amit.shah@redhat.com>
Cc: qemu list <qemu-devel@nongnu.org>


----- "Amit Shah" <amit.shah@redhat.com> wrote:

> If a virtio-serial port is removed before the guest comes up and
> initialises the virtqueues, qemu exits with the message
> 
> Guest moved used index from 0 to 61440
> 
> This happens because we try to clear any pending buffers from the
> virtqueue.
> 
> Ensure the virtqueue is initialised before calling any virtqueue
> operations.
> 
> Signed-off-by: Amit Shah <amit.shah@redhat.com>
> ---
>  hw/virtio-serial-bus.c |    3 +++
>  1 files changed, 3 insertions(+), 0 deletions(-)
> 
> diff --git a/hw/virtio-serial-bus.c b/hw/virtio-serial-bus.c
> index 7f9d28f..b89daa6 100644
> --- a/hw/virtio-serial-bus.c
> +++ b/hw/virtio-serial-bus.c
> @@ -139,6 +139,9 @@ static void flush_queued_data(VirtIOSerialPort
> *port, bool discard)
>  {
>      assert(port);
>  
> +    if (!virtio_queue_ready(port->ovq)) {
> +        return;
> +    }
>      do_flush_queued_data(port, port->ovq, &port->vser->vdev,
> discard);
>  }
>  
> -- 
> 1.7.0.1

ACK series