[libvirt] [PATCH for v1.0.4-maint 1/2] qemu: Resolve issue with GetScheduler APIs for non running domain

[John Ferlan]

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.

Conflicts:
	src/qemu/qemu_driver.c

 * Resolved conflict by using former qemuCgroupHasController() rather than
   virCgroupHasController()
 * Needed to add the code to fetch the 'vm'
      vm = virDomainObjListFindByUUID(driver->domains, dom->uuid);
      if (vm == NULL) {
          virReportError(VIR_ERR_INTERNAL_ERROR,
                         _("No such domain %s"), dom->uuid);
          goto cleanup;
      }
* Used 'ret = strdup("posix");' rather than VIR_STRDUP(ret, "posix");
---
 src/qemu/qemu_driver.c | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index b6a5139..bfa10c4 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -6734,6 +6734,22 @@ static char *qemuGetSchedulerType(virDomainPtr dom,
     virQEMUDriverPtr driver = dom->conn->privateData;
     char *ret = NULL;
     int rc;
+    virDomainObjPtr vm = NULL;
+
+    vm = virDomainObjListFindByUUID(driver->domains, dom->uuid);
+    if (vm == NULL) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("No such domain %s"), dom->uuid);
+        goto cleanup;
+    }
+
+    /* Domain not running, thus no cgroups - return defaults */
+    if (!virDomainObjIsActive(vm)) {
+        if (nparams)
+            *nparams = 5;
+        ret = strdup("posix");
+        goto cleanup;
+    }
 
     if (!qemuCgroupControllerActive(driver, VIR_CGROUP_CONTROLLER_CPU)) {
         virReportError(VIR_ERR_OPERATION_INVALID,
@@ -8227,11 +8243,12 @@ qemuGetSchedulerParametersFlags(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;
     }
-- 
1.8.1.4