qemu_driver: check whether iothread is used by controller

This follows the same check for disk, because we cannot remove iothread
if it's used by disk or by controller.  It could lead to crashing QEMU.

Signed-off-by: Pavel Hrdina <phrdina@redhat.com>

src/qemu/qemu_driver.c

@@ -5749,6 +5749,16 @@ qemuDomainDelIOThreadCheck(virDomainDefPtr def,
         }
     }
 
+    for (i = 0; i < def->ncontrollers; i++) {
+        if (def->controllers[i]->iothread == iothread_id) {
+            virReportError(VIR_ERR_INVALID_ARG,
+                           _("cannot remove IOThread '%u' since it "
+                             "is being used by controller"),
+                           iothread_id);
+            return -1;
+        }
+    }
+
     return 0;
 }