[libvirt] [PATCH v2 2/2] lxc: Resolve issue with GetScheduler APIs for non running domain

[John Ferlan]

As a consequence of the cgroup layout changes from commit 'cfed9ad4', the
lxcDomainGetSchedulerParameters[Flags]()' and lxcGetSchedulerType() 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.
---
 src/lxc/lxc_driver.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/src/lxc/lxc_driver.c b/src/lxc/lxc_driver.c
index 3d6baf5..4ab1736 100644
--- a/src/lxc/lxc_driver.c
+++ b/src/lxc/lxc_driver.c
@@ -1617,6 +1617,14 @@ static char *lxcDomainGetSchedulerType(virDomainPtr dom,
     }
     priv = vm->privateData;
 
+    /* Domain not running, thus no cgroups - return defaults */
+    if (!virDomainObjIsActive(vm)) {
+        if (nparams)
+            *nparams = 3;
+        ignore_value(VIR_STRDUP(ret, "posix"));
+        goto cleanup;
+    }
+
     if (!virCgroupHasController(priv->cgroup, VIR_CGROUP_CONTROLLER_CPU)) {
         virReportError(VIR_ERR_OPERATION_INVALID,
                        "%s", _("cgroup CPU controller is not mounted"));
@@ -1895,9 +1903,10 @@ lxcDomainGetSchedulerParametersFlags(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;
+            cpu_bw_status = true; /* Allow copy of data to params[] */
         }
         goto out;
     }
-- 
1.8.1.4