Introduce the function virCgroupForEmulator

Introduce the function virCgroupForEmulator() to create sub directory
for simulator thread(include I/O thread, vhost-net thread)
Signed-off-by: NWen Congyang <wency@cn.fujitsu.com>
Signed-off-by: NTang Chen <tangchen@cn.fujitsu.com>
Signed-off-by: NHu Tao <hutao@cn.fujitsu.com>

src/libvirt_private.syms

@@ -71,6 +71,7 @@ virCgroupDenyDeviceMajor;
 virCgroupDenyDevicePath;
 virCgroupForDomain;
 virCgroupForDriver;
+virCgroupForEmulator;
 virCgroupForVcpu;
 virCgroupFree;
 virCgroupGetBlkioWeight;

src/util/cgroup.c

@@ -956,6 +956,48 @@ int virCgroupForVcpu(virCgroupPtr driver ATTRIBUTE_UNUSED,
 }
 #endif
 
+/**
+ * virCgroupForEmulator:
+ *
+ * @driver: group for the domain
+ * @group: Pointer to returned virCgroupPtr
+ *
+ * Returns: 0 on success or -errno on failure
+ */
+#if defined HAVE_MNTENT_H && defined HAVE_GETMNTENT_R
+int virCgroupForEmulator(virCgroupPtr driver,
+                          virCgroupPtr *group,
+                          int create)
+{
+    int rc;
+    char *path;
+
+    if (driver == NULL)
+        return -EINVAL;
+
+    if (virAsprintf(&path, "%s/emulator", driver->path) < 0)
+        return -ENOMEM;
+
+    rc = virCgroupNew(path, group);
+    VIR_FREE(path);
+
+    if (rc == 0) {
+        rc = virCgroupMakeGroup(driver, *group, create, VIR_CGROUP_VCPU);
+        if (rc != 0)
+            virCgroupFree(group);
+    }
+
+    return rc;
+}
+#else
+int virCgroupForEmulator(virCgroupPtr driver ATTRIBUTE_UNUSED,
+                          virCgroupPtr *group ATTRIBUTE_UNUSED,
+                          int create ATTRIBUTE_UNUSED)
+{
+    return -ENXIO;
+}
+
+#endif
 /**
  * virCgroupSetBlkioWeight:
  *

src/util/cgroup.h

@@ -59,6 +59,10 @@ int virCgroupForVcpu(virCgroupPtr driver,
                      virCgroupPtr *group,
                      int create);
 
+int virCgroupForEmulator(virCgroupPtr driver,
+                         virCgroupPtr *group,
+                         int create);
+
 int virCgroupPathOfController(virCgroupPtr group,
                               int controller,
                               const char *key,