If the guest is unresponsive and 'info balloon' is invoked, the monitor process just hangs waiting for info from the guest. Return the most recent balloon data in that case.
A new timer is added, which on expiry, just presents the old data to the monitor callback functions. See https://bugzilla.redhat.com/show_bug.cgi?id=623903 Reported-by: <lihu...@redhat.com> Signed-off-by: Amit Shah <amit.s...@redhat.com> --- hw/virtio-balloon.c | 11 +++++++++++ 1 files changed, 11 insertions(+), 0 deletions(-) diff --git a/hw/virtio-balloon.c b/hw/virtio-balloon.c index 9fe3886..d6c66cf 100644 --- a/hw/virtio-balloon.c +++ b/hw/virtio-balloon.c @@ -40,6 +40,7 @@ typedef struct VirtIOBalloon size_t stats_vq_offset; MonitorCompletion *stats_callback; void *stats_opaque_callback_data; + QEMUTimer *timer; } VirtIOBalloon; static VirtIOBalloon *to_virtio_balloon(VirtIODevice *vdev) @@ -137,6 +138,11 @@ static void complete_stats_request(VirtIOBalloon *vb) vb->stats_callback = NULL; } +static void show_old_stats(void *opaque) +{ + complete_stats_request(opaque); +} + static void virtio_balloon_receive_stats(VirtIODevice *vdev, VirtQueue *vq) { VirtIOBalloon *s = DO_UPCAST(VirtIOBalloon, vdev, vdev); @@ -148,6 +154,8 @@ static void virtio_balloon_receive_stats(VirtIODevice *vdev, VirtQueue *vq) return; } + qemu_del_timer(s->timer); + /* Initialize the stats to get rid of any stale values. This is only * needed to handle the case where a guest supports fewer stats than it * used to (ie. it has booted into an old kernel). @@ -215,6 +223,7 @@ static void virtio_balloon_to_target(void *opaque, ram_addr_t target, dev->stats_callback = cb; dev->stats_opaque_callback_data = cb_data; if (dev->vdev.guest_features & (1 << VIRTIO_BALLOON_F_STATS_VQ)) { + qemu_mod_timer(dev->timer, qemu_get_clock(rt_clock) + 5000); virtqueue_push(dev->svq, &dev->stats_vq_elem, dev->stats_vq_offset); virtio_notify(&dev->vdev, dev->svq); } else { @@ -267,6 +276,8 @@ VirtIODevice *virtio_balloon_init(DeviceState *dev) s->dvq = virtio_add_queue(&s->vdev, 128, virtio_balloon_handle_output); s->svq = virtio_add_queue(&s->vdev, 128, virtio_balloon_receive_stats); + s->timer = qemu_new_timer(rt_clock, show_old_stats, s); + reset_stats(s); qemu_add_balloon_handler(virtio_balloon_to_target, s); -- 1.7.2.2
