[PATCH v2 1/3] vircgroup: Introduce virCgroupControllerAvailable

[Michal Privoznik <mprivozn@xxxxxxxxxx>]

This new internal API checks if given CGroup controller is
available.  It is going to be needed later when we need to make a
decision whether pin domain memory onto NUMA nodes using cpuset
CGroup controller or using numa_set_membind().

Signed-off-by: Michal Privoznik <mprivozn@xxxxxxxxxx>
---
 src/libvirt_private.syms |  1 +
 src/util/vircgroup.c     | 19 +++++++++++++++++++
 src/util/vircgroup.h     |  1 +
 tests/vircgrouptest.c    | 31 +++++++++++++++++++++++++++++++
 4 files changed, 52 insertions(+)

diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index 5716ece..136036b 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -1129,6 +1129,7 @@ virCgroupAllowDevice;
 virCgroupAllowDeviceMajor;
 virCgroupAllowDevicePath;
 virCgroupAvailable;
+virCgroupControllerAvailable;
 virCgroupControllerTypeFromString;
 virCgroupControllerTypeToString;
 virCgroupDenyAllDevices;
diff --git a/src/util/vircgroup.c b/src/util/vircgroup.c
index d42f433..00c0bab 100644
--- a/src/util/vircgroup.c
+++ b/src/util/vircgroup.c
@@ -4011,6 +4011,20 @@ virCgroupHasEmptyTasks(virCgroupPtr cgroup, int controller)
     return ret;
 }
 
+bool
+virCgroupControllerAvailable(int controller)
+{
+    virCgroupPtr cgroup;
+    bool ret = false;
+
+    if (virCgroupNewSelf(&cgroup) < 0)
+        return ret;
+
+    ret = virCgroupHasController(cgroup, controller);
+    virCgroupFree(&cgroup);
+    return ret;
+}
+
 #else /* !VIR_CGROUP_SUPPORTED */
 
 bool
@@ -4781,4 +4795,9 @@ virCgroupHasEmptyTasks(virCgroupPtr cgroup ATTRIBUTE_UNUSED,
     return -1;
 }
 
+bool
+virCgroupControllerAvailable(int controller ATTRIBUTE_UNUSED)
+{
+    return false;
+}
 #endif /* !VIR_CGROUP_SUPPORTED */
diff --git a/src/util/vircgroup.h b/src/util/vircgroup.h
index eee15ca..5d6356d 100644
--- a/src/util/vircgroup.h
+++ b/src/util/vircgroup.h
@@ -282,4 +282,5 @@ int virCgroupSetOwner(virCgroupPtr cgroup,
 
 int virCgroupHasEmptyTasks(virCgroupPtr cgroup, int controller);
 
+bool virCgroupControllerAvailable(int controller);
 #endif /* __VIR_CGROUP_H__ */
diff --git a/tests/vircgrouptest.c b/tests/vircgrouptest.c
index bbf28d1..2b30258 100644
--- a/tests/vircgrouptest.c
+++ b/tests/vircgrouptest.c
@@ -586,6 +586,34 @@ static int testCgroupAvailable(const void *args)
     return 0;
 }
 
+static int testCgroupControllerAvailable(const void *args ATTRIBUTE_UNUSED)
+{
+    int ret = 0;
+
+# define CHECK_CONTROLLER(c, present)                                   \
+    if ((present && !virCgroupControllerAvailable(c)) ||                \
+        (!present && virCgroupControllerAvailable(c))) {                \
+        fprintf(stderr, present ?                                       \
+                "Expected controller %s not available\n" :              \
+                "Unexpected controller %s available\n", #c);            \
+        ret = -1;                                                       \
+    }
+
+    CHECK_CONTROLLER(VIR_CGROUP_CONTROLLER_CPU, true)
+    CHECK_CONTROLLER(VIR_CGROUP_CONTROLLER_CPUACCT, true)
+    CHECK_CONTROLLER(VIR_CGROUP_CONTROLLER_CPUSET, true)
+    CHECK_CONTROLLER(VIR_CGROUP_CONTROLLER_MEMORY, true)
+    CHECK_CONTROLLER(VIR_CGROUP_CONTROLLER_DEVICES, false)
+    CHECK_CONTROLLER(VIR_CGROUP_CONTROLLER_FREEZER, true)
+    CHECK_CONTROLLER(VIR_CGROUP_CONTROLLER_BLKIO, true)
+    CHECK_CONTROLLER(VIR_CGROUP_CONTROLLER_NET_CLS, false)
+    CHECK_CONTROLLER(VIR_CGROUP_CONTROLLER_PERF_EVENT, false)
+    CHECK_CONTROLLER(VIR_CGROUP_CONTROLLER_SYSTEMD, true)
+
+# undef CHECK_CONTROLLER
+    return ret;
+}
+
 static int testCgroupGetPercpuStats(const void *args ATTRIBUTE_UNUSED)
 {
     virCgroupPtr cgroup = NULL;
@@ -886,6 +914,9 @@ mymain(void)
     if (virtTestRun("Cgroup available", testCgroupAvailable, (void*)0x1) < 0)
         ret = -1;
 
+    if (virtTestRun("Cgroup controller available", testCgroupControllerAvailable, NULL) < 0)
+        ret = -1;
+
     if (virtTestRun("virCgroupGetBlkioIoServiced works", testCgroupGetBlkioIoServiced, NULL) < 0)
         ret = -1;
 
-- 
2.0.5

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