qemu_hotplug: Clear QoS if required in qemuDomainChangeNet()

In one of my recent commits, I've introduced
virDomainInterfaceClearQoS() which is a helper that either calls
virNetDevBandwidthClear() ('tc' implementation) or
virNetDevOpenvswitchInterfaceClearQos() (for ovs ifaces). But I
made a micro optimization which leads to a bug: the function
checks whether passed iface has any QoS set and returns early if
it has none. In majority of cases this is right thing to do, but
when removing QoS on virDomainUpdateDeviceFlags() this is
problematic. The new definition (passed as argument to
virDomainInterfaceClearQoS()) contains no QoS (because user
requested its removal) and thus instead of removing the old QoS
setting nothing is done.

Fortunately, the fix is simple - pass olddev which contains the
old QoS setting.

Fixes: 812a146dfe784315edece43d09f8d9e432f8230e
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Jiri Denemark <jdenemar@redhat.com>

diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
index 4739beead8811e5ed3a610fe0c1eb2a002804099..c98b0b5d523ba9d0292ded83d22655f90978f17b 100644 (file)
--- a/src/qemu/qemu_hotplug.c
+++ b/src/qemu/qemu_hotplug.c
@@ -4071,7 +4071,7 @@ qemuDomainChangeNet(virQEMUDriver *driver,
                 goto cleanup;
             }
         } else {
-            if (virDomainInterfaceClearQoS(vm->def, newdev) < 0)
+            if (virDomainInterfaceClearQoS(vm->def, olddev) < 0)
                 goto cleanup;
         }