From bcfa563707541ab415d6430a0e7ef5bb31cf3200 Mon Sep 17 00:00:00 2001
From: Pavel Hrdina <phrdina@redhat.com>
Date: Tue, 3 Nov 2020 13:27:08 +0100
Subject: [PATCH] vircgroup: introduce virCgroupNewParent

The current code uses virCgroupNew() as a single point of entry and
calls into virCgroupDetect() as well. Both have logic for several paths
which is difficult to figure out.

Extract the actually used code path from the two functions to make
it obvious what's happening in this case.

Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
---
 src/util/vircgroup.c | 51 ++++++++++++++++++++++++++++++++++++--------
 1 file changed, 42 insertions(+), 9 deletions(-)

diff --git a/src/util/vircgroup.c b/src/util/vircgroup.c
index 97e15c0ab3..b11139bef1 100644
--- a/src/util/vircgroup.c
+++ b/src/util/vircgroup.c
@@ -861,6 +861,40 @@ virCgroupSetPartitionSuffix(const char *path, char **res)
 }
 
 
+static int
+virCgroupNewFromParent(virCgroupPtr parent,
+                       const char *path,
+                       int controllers,
+                       virCgroupPtr *group)
+{
+    g_autoptr(virCgroup) new = g_new0(virCgroup, 1);
+
+    VIR_DEBUG("parent=%p path=%s controllers=%d group=%p",
+              parent, path, controllers, group);
+
+    if (virCgroupSetBackends(new) < 0)
+        return -1;
+
+    if (virCgroupCopyMounts(new, parent) < 0)
+        return -1;
+
+    if (virCgroupCopyPlacement(new, path, parent) < 0)
+        return -1;
+
+    if (virCgroupDetectPlacement(new, -1, path) < 0)
+        return -1;
+
+    if (virCgroupValidatePlacement(new, -1) < 0)
+        return -1;
+
+    if (virCgroupDetectControllers(new, controllers, parent) < 0)
+        return -1;
+
+    *group = g_steal_pointer(&new);
+    return 0;
+}
+
+
 /**
  * virCgroupNewPartition:
  * @path: path for the partition
@@ -910,7 +944,7 @@ virCgroupNewPartition(const char *path,
             return -1;
     }
 
-    if (virCgroupNew(-1, newPath, parent, controllers, &newGroup) < 0)
+    if (virCgroupNewFromParent(parent, newPath, controllers, &newGroup) < 0)
         return -1;
 
     if (parent) {
@@ -965,7 +999,7 @@ virCgroupNewDomainPartition(virCgroupPtr partition,
     if (virCgroupPartitionEscape(&grpname) < 0)
         return -1;
 
-    if (virCgroupNew(-1, grpname, partition, -1, &newGroup) < 0)
+    if (virCgroupNewFromParent(partition, grpname, -1, &newGroup) < 0)
         return -1;
 
     /*
@@ -1032,7 +1066,7 @@ virCgroupNewThread(virCgroupPtr domain,
                    (1 << VIR_CGROUP_CONTROLLER_CPUACCT) |
                    (1 << VIR_CGROUP_CONTROLLER_CPUSET));
 
-    if (virCgroupNew(-1, name, domain, controllers, &newGroup) < 0)
+    if (virCgroupNewFromParent(domain, name, controllers, &newGroup) < 0)
         return -1;
 
     if (virCgroupMakeGroup(domain, newGroup, create, VIR_CGROUP_THREAD) < 0)
@@ -1133,11 +1167,10 @@ virCgroupEnableMissingControllers(char *path,
         if (t)
             *t = '\0';
 
-        if (virCgroupNew(pidleader,
-                         path,
-                         parent,
-                         controllers,
-                         &tmp) < 0)
+        if (virCgroupNewFromParent(parent,
+                                   path,
+                                   controllers,
+                                   &tmp) < 0)
             return -1;
 
         if (virCgroupMakeGroup(parent, tmp, true, VIR_CGROUP_SYSTEMD) < 0)
@@ -2583,7 +2616,7 @@ virCgroupKillRecursiveInternal(virCgroupPtr group,
 
         VIR_DEBUG("Process subdir %s", ent->d_name);
 
-        if (virCgroupNew(-1, ent->d_name, group, -1, &subgroup) < 0)
+        if (virCgroupNewFromParent(group, ent->d_name, -1, &subgroup) < 0)
             return -1;
 
         if ((rc = virCgroupKillRecursiveInternal(subgroup, signum, pids,