From cb5281b1998c12b8d93d0c6a29aeae13934ceb1a Mon Sep 17 00:00:00 2001
From: Amit Shah <amit.shah@redhat.com>
Date: Fri, 4 Feb 2011 14:24:18 +0530
Subject: virtio-serial: Make sure virtqueue is ready before discarding data

This can happen if a port gets unplugged before guest has chance to
initialise vqs.

Reported-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
(cherry picked from commit 7185f9315bcf90e99b123370cf4d19b8c20afbd5)
---
 hw/virtio-serial-bus.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/hw/virtio-serial-bus.c b/hw/virtio-serial-bus.c
index 09e22aa44a..e05ab5e609 100644
--- a/hw/virtio-serial-bus.c
+++ b/hw/virtio-serial-bus.c
@@ -117,6 +117,9 @@ static void discard_vq_data(VirtQueue *vq, VirtIODevice *vdev)
 {
     VirtQueueElement elem;
 
+    if (!virtio_queue_ready(vq)) {
+        return;
+    }
     while (virtqueue_pop(vq, &elem)) {
         virtqueue_push(vq, &elem, 0);
     }
-- 
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