qemu: Resolve issue with GetScheduler APIs for non running domain

Cherry-picked from b23754534193fb7a1e31306d94ae5f09759a0aa4

As a consequence of the cgroup layout changes from commit '632f78ca', the
qemuDomainGetSchedulerParameters[Flags]()' and qemuGetSchedulerType() APIs
failed to return data for a non running domain.  This can be seen through
a 'virsh schedinfo <domain>' command which returns:

Scheduler      : Unknown
error: Requested operation is not valid: cgroup CPU controller is not mounted

Prior to that change a non running domain would return:

Scheduler      : posix
cpu_shares     : 0
vcpu_period    : 0
vcpu_quota     : 0
emulator_period: 0
emulator_quota : 0

This patch will restore the capability to return configuration only data
for a non running domain regardless of whether cgroups are available.

NOTE: Needed to change the VIR_STRDUP(ret, "posix"); to ret = strdup("posix");
      and added the virReportOOMError(); on failure.

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 31b2f8569a9dc44d9a494221f6378d59941d0d2d..631e6f440dc3459b50db306228620c645441fd4c 100644 (file)
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -6619,6 +6619,16 @@ static char *qemuDomainGetSchedulerType(virDomainPtr dom,
     }
     priv = vm->privateData;
 
+    /* Domain not running, thus no cgroups - return defaults */
+    if (!virDomainObjIsActive(vm)) {
+        if (nparams)
+            *nparams = 5;
+        ret = strdup("posix");
+        if (!ret)
+            virReportOOMError();
+        goto cleanup;
+    }
+
     if (!virCgroupHasController(priv->cgroup, VIR_CGROUP_CONTROLLER_CPU)) {
         virReportError(VIR_ERR_OPERATION_INVALID,
                        "%s", _("cgroup CPU controller is not mounted"));
@@ -8038,11 +8048,12 @@ qemuDomainGetSchedulerParametersFlags(virDomainPtr dom,
 
     if (flags & VIR_DOMAIN_AFFECT_CONFIG) {
         shares = persistentDef->cputune.shares;
-        if (*nparams > 1 && cpu_bw_status) {
+        if (*nparams > 1) {
             period = persistentDef->cputune.period;
             quota = persistentDef->cputune.quota;
             emulator_period = persistentDef->cputune.emulator_period;
             emulator_quota = persistentDef->cputune.emulator_quota;
+            cpu_bw_status = true; /* Allow copy of data to params[] */
         }
         goto out;
     }