nspawn: rework mount_systemd_cgroup_writable() a bit

We shouldn't call alloca() as part of function calls, that's not really
defined in C. Hence, let's first do our stack allocations, and then
invoke functions.

Also, some coding style fixes, and minor shuffling around.

No functional changes.

diff --git a/src/nspawn/nspawn-mount.c b/src/nspawn/nspawn-mount.c
index c8c941cdfdba33553b885a6a62bb1c5d3ce4582e..69707cb7f988ae109520df1f0c3cdad599afef72 100644 (file)
--- a/src/nspawn/nspawn-mount.c
+++ b/src/nspawn/nspawn-mount.c
@@ -1213,23 +1213,25 @@ int mount_cgroups(
 
         if (unified_requested >= CGROUP_UNIFIED_ALL)
                 return mount_unified_cgroups(dest);
-        else if (use_cgns)
+        if (use_cgns)
                 return mount_legacy_cgns_supported(dest, unified_requested, userns, uid_shift, uid_range, selinux_apifs_context);
 
         return mount_legacy_cgns_unsupported(dest, unified_requested, userns, uid_shift, uid_range, selinux_apifs_context);
 }
 
-static int mount_systemd_cgroup_writable_one(const char *systemd_own, const char *systemd_root)
-{
+static int mount_systemd_cgroup_writable_one(const char *root, const char *own) {
         int r;
 
+        assert(root);
+        assert(own);
+
         /* Make our own cgroup a (writable) bind mount */
-        r = mount_verbose(LOG_ERR, systemd_own, systemd_own,  NULL, MS_BIND, NULL);
+        r = mount_verbose(LOG_ERR, own, own, NULL, MS_BIND, NULL);
         if (r < 0)
                 return r;
 
         /* And then remount the systemd cgroup root read-only */
-        return mount_verbose(LOG_ERR, NULL, systemd_root, NULL,
+        return mount_verbose(LOG_ERR, NULL, root, NULL,
                              MS_BIND|MS_REMOUNT|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_RDONLY, NULL);
 }
 
@@ -1238,6 +1240,7 @@ int mount_systemd_cgroup_writable(
                 CGroupUnified unified_requested) {
 
         _cleanup_free_ char *own_cgroup_path = NULL;
+        const char *root, *own;
         int r;
 
         assert(dest);
@@ -1250,19 +1253,27 @@ int mount_systemd_cgroup_writable(
         if (path_equal(own_cgroup_path, "/"))
                 return 0;
 
-        if (unified_requested >= CGROUP_UNIFIED_ALL)
-                return mount_systemd_cgroup_writable_one(strjoina(dest, "/sys/fs/cgroup", own_cgroup_path),
-                                                         prefix_roota(dest, "/sys/fs/cgroup"));
+        if (unified_requested >= CGROUP_UNIFIED_ALL) {
 
-        if (unified_requested >= CGROUP_UNIFIED_SYSTEMD) {
-                r = mount_systemd_cgroup_writable_one(strjoina(dest, "/sys/fs/cgroup/unified", own_cgroup_path),
-                                                      prefix_roota(dest, "/sys/fs/cgroup/unified"));
-                if (r < 0)
-                        return r;
+                root = prefix_roota(dest, "/sys/fs/cgroup");
+                own = strjoina(root, own_cgroup_path);
+
+        } else {
+
+                if (unified_requested >= CGROUP_UNIFIED_SYSTEMD) {
+                        root = prefix_roota(dest, "/sys/fs/cgroup/unified");
+                        own = strjoina(root, own_cgroup_path);
+
+                        r = mount_systemd_cgroup_writable_one(root, own);
+                        if (r < 0)
+                                return r;
+                }
+
+                root = prefix_roota(dest, "/sys/fs/cgroup/systemd");
+                own = strjoina(root, own_cgroup_path);
         }
 
-        return mount_systemd_cgroup_writable_one(strjoina(dest, "/sys/fs/cgroup/systemd", own_cgroup_path),
-                                                 prefix_roota(dest, "/sys/fs/cgroup/systemd"));
+        return mount_systemd_cgroup_writable_one(root, own);
 }
 
 int setup_volatile_state(