virtio-balloon: Separate status handling into separate function

Separate out the code to retrieve balloon info from the code that sets
balloon values.

This will be used to separate the two callbacks from balloon.c and help
cope with 'balloon 0' on the monitor.  Currently, 'balloon 0' causes a
segfault in monitor_resume().

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>

diff --git a/hw/virtio-balloon.c b/hw/virtio-balloon.c
index 70a87103439ac0205eedb88b244ca9d3aa759174..2f371f2f6963c003f9ed86ba0140aede2c61b8df 100644 (file)
--- a/hw/virtio-balloon.c
+++ b/hw/virtio-balloon.c
@@ -199,36 +199,47 @@ static uint32_t virtio_balloon_get_features(VirtIODevice *vdev, uint32_t f)
     return f;
 }
 
+static void virtio_balloon_stat(void *opaque, MonitorCompletion cb,
+                                void *cb_data)
+{
+    VirtIOBalloon *dev = opaque;
+
+    /* For now, only allow one request at a time.  This restriction can be
+     * removed later by queueing callback and data pairs.
+     */
+    if (dev->stats_callback != NULL) {
+        return;
+    }
+    dev->stats_callback = cb;
+    dev->stats_opaque_callback_data = cb_data;
+
+    if (ENABLE_GUEST_STATS
+        && (dev->vdev.guest_features & (1 << VIRTIO_BALLOON_F_STATS_VQ))) {
+        virtqueue_push(dev->svq, &dev->stats_vq_elem, dev->stats_vq_offset);
+        virtio_notify(&dev->vdev, dev->svq);
+        return;
+    }
+
+    /* Stats are not supported.  Clear out any stale values that might
+     * have been set by a more featureful guest kernel.
+     */
+    reset_stats(dev);
+    complete_stats_request(dev);
+}
+
 static void virtio_balloon_to_target(void *opaque, ram_addr_t target,
                                      MonitorCompletion cb, void *cb_data)
 {
     VirtIOBalloon *dev = opaque;
 
-    if (target > ram_size)
+    if (target > ram_size) {
         target = ram_size;
-
+    }
     if (target) {
         dev->num_pages = (ram_size - target) >> VIRTIO_BALLOON_PFN_SHIFT;
         virtio_notify_config(&dev->vdev);
     } else {
-        /* For now, only allow one request at a time.  This restriction can be
-         * removed later by queueing callback and data pairs.
-         */
-        if (dev->stats_callback != NULL) {
-            return;
-        }
-        dev->stats_callback = cb;
-        dev->stats_opaque_callback_data = cb_data; 
-        if (ENABLE_GUEST_STATS && (dev->vdev.guest_features & (1 << VIRTIO_BALLOON_F_STATS_VQ))) {
-            virtqueue_push(dev->svq, &dev->stats_vq_elem, dev->stats_vq_offset);
-            virtio_notify(&dev->vdev, dev->svq);
-        } else {
-            /* Stats are not supported.  Clear out any stale values that might
-             * have been set by a more featureful guest kernel.
-             */
-            reset_stats(dev);
-            complete_stats_request(dev);
-        }
+        virtio_balloon_stat(opaque, cb, cb_data);
     }
 }