commit 46abb8124006887d071921c5e657eeec3c50a9e2
author Luiz Capitulino <lcapitulino@redhat.com> Tue Mar 31 13:00:26 2015 -0400
committer Luiz Capitulino <lcapitulino@redhat.com> Fri Apr 24 14:18:05 2015 -0400
tree 6e6d3c985da30d59a9973ad11047c2c6fd5646fb
parent e5b3a24181ea0cebf1c5b20f44d016311b7048f0

balloon: improve error msg when adding second device

A VM supports only one balloon device, but due to several changes
in infrastructure the error message got messed up when trying
to add a second device. Fix it.

Before this fix

Command-line:

qemu-qmp: -device virtio-balloon-pci,id=balloon0: Another balloon device already registered
qemu-qmp: -device virtio-balloon-pci,id=balloon0: Adding balloon handler failed
qemu-qmp: -device virtio-balloon-pci,id=balloon0: Device 'virtio-balloon-pci' could not be initialized

HMP:

Another balloon device already registered
Adding balloon handler failed
Device 'virtio-balloon-pci' could not be initialized

QMP:

{ "execute": "device_add", "arguments": { "driver": "virtio-balloon-pci", "id": "balloon0" } }
{
	"error": {
		"class": "GenericError",
		"desc": "Adding balloon handler failed"
	}
}

After this fix

Command-line:

qemu-qmp: -device virtio-balloon-pci,id=balloon0: Only one balloon device is supported
qemu-qmp: -device virtio-balloon-pci,id=balloon0: Device 'virtio-balloon-pci' could not be initialized

HMP:

(qemu) device_add virtio-balloon-pci,id=balloon0
Only one balloon device is supported
Device 'virtio-balloon-pci' could not be initialized
(qemu)

QMP:

{ "execute": "device_add",
          "arguments": { "driver": "virtio-balloon-pci", "id": "balloon0" } }
{
    "error": {
        "class": "GenericError",
        "desc": "Only one balloon device is supported"
    }
}

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>

hw/virtio/virtio-balloon.c

diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index 95b0643..484c3c3 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -383,7 +383,7 @@
                                    virtio_balloon_stat, s);
 
     if (ret < 0) {
-        error_setg(errp, "Adding balloon handler failed");
+        error_setg(errp, "Only one balloon device is supported");
         virtio_cleanup(vdev);
         return;
     }