qemu: Don't fail stats collection due to IOThread capability

Commit 212dc928 made a generic qemuDomainGetIOThreadsMon which
would fail if the QEMU_CAPS_OBJECT_IOTHREAD didn't exist. Then
commit d1eac927 used that helper for the collection of all domain
stats. However, if the capability doesn't exist, then the entire
stats collection fails. Since the IOThread stats were meant to be
if available only, thus rather than failing if the capability
doesn't exist, let's just not collect the stats. Restore the caps
failure logic for qemuDomainGetIOThreadsLive.
Signed-off-by: NJohn Ferlan <jferlan@redhat.com>
Reviewed-by: NJán Tomko <jtomko@redhat.com>

src/qemu/qemu_driver.c

@@ -5498,16 +5498,9 @@ qemuDomainGetIOThreadsMon(virQEMUDriverPtr driver,
                           virDomainObjPtr vm,
                           qemuMonitorIOThreadInfoPtr **iothreads)
 {
-    qemuDomainObjPrivatePtr priv;
+    qemuDomainObjPrivatePtr priv = vm->privateData;
     int niothreads = 0;
 
-    priv = vm->privateData;
-    if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_OBJECT_IOTHREAD)) {
-        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
-                       _("IOThreads not supported with this binary"));
-        return -1;
-    }
-
     qemuDomainObjEnterMonitor(driver, vm);
     niothreads = qemuMonitorGetIOThreads(priv->mon, iothreads);
     if (qemuDomainObjExitMonitor(driver, vm) < 0 || niothreads < 0)
@@ -5522,6 +5515,7 @@ qemuDomainGetIOThreadsLive(virQEMUDriverPtr driver,
                            virDomainObjPtr vm,
                            virDomainIOThreadInfoPtr **info)
 {
+    qemuDomainObjPrivatePtr priv;
     qemuMonitorIOThreadInfoPtr *iothreads = NULL;
     virDomainIOThreadInfoPtr *info_ret = NULL;
     int niothreads = 0;
@@ -5537,6 +5531,13 @@ qemuDomainGetIOThreadsLive(virQEMUDriverPtr driver,
         goto endjob;
     }
 
+    priv = vm->privateData;
+    if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_OBJECT_IOTHREAD)) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                       _("IOThreads not supported with this binary"));
+        goto endjob;
+    }
+
     if ((niothreads = qemuDomainGetIOThreadsMon(driver, vm, &iothreads)) < 0)
         goto endjob;
 
@@ -20882,6 +20883,7 @@ qemuDomainGetStatsIOThread(virQEMUDriverPtr driver,
                            int *maxparams,
                            unsigned int privflags ATTRIBUTE_UNUSED)
 {
+    qemuDomainObjPrivatePtr priv = dom->privateData;
     size_t i;
     qemuMonitorIOThreadInfoPtr *iothreads = NULL;
     int niothreads;
@@ -20890,6 +20892,9 @@ qemuDomainGetStatsIOThread(virQEMUDriverPtr driver,
     if (!virDomainObjIsActive(dom))
         return 0;
 
+    if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_OBJECT_IOTHREAD))
+        return 0;
+
     if ((niothreads = qemuDomainGetIOThreadsMon(driver, dom, &iothreads)) < 0)
         return -1;