cgroups: honor lxc.cgroup.pattern if set explicitly II

Link: https://discuss.linuxcontainers.org/t/lxc-cgroup-pattern-is-not-being-honored
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

src/lxc/cgroups/cgfsng.c

@@ -1223,21 +1223,14 @@ static void cgroup_remove_leaf(struct hierarchy *h, bool payload)
 
 	if (payload) {
 		__lxc_unused __do_close_prot_errno int fd = move_fd(h->cgfd_con);
-		h->cgfd_con = -EBADF;
-		full_path = h->container_full_path;
+		full_path = move_ptr(h->container_full_path);
 	} else {
 		__lxc_unused __do_close_prot_errno int fd = move_fd(h->cgfd_mon);
-		h->cgfd_mon = -EBADF;
-		full_path = h->monitor_full_path;
+		full_path = move_ptr(h->monitor_full_path);
 	}
 
-	if (rmdir(full_path))
+	if (full_path && rmdir(full_path))
 		SYSWARN("Failed to rmdir(\"%s\") cgroup", full_path);
-
-	if (payload)
-		h->container_full_path = NULL;
-	else
-		h->monitor_full_path = NULL;
 }
 
 __cgfsng_ops static inline bool cgfsng_monitor_create(struct cgroup_ops *ops,
@@ -1273,10 +1266,15 @@ __cgfsng_ops static inline bool cgfsng_monitor_create(struct cgroup_ops *ops,
 					     CGROUP_CREATE_RETRY, NULL);
 	} else if (ops->cgroup_pattern) {
 		__cgroup_tree = lxc_string_replace("%n", handler->name, ops->cgroup_pattern);
+		if (!__cgroup_tree)
+			return ret_set_errno(false, ENOMEM);
+
 		cgroup_tree = __cgroup_tree;
-		monitor_cgroup = must_concat(&len, cgroup_tree,
+		monitor_cgroup = must_concat(&len, cgroup_tree, "/",
+					     DEFAULT_MONITOR_CGROUP,
 					     CGROUP_CREATE_RETRY, NULL);
 	} else {
+		cgroup_tree = NULL;
 		monitor_cgroup = must_concat(&len, DEFAULT_MONITOR_CGROUP_PREFIX,
 					     handler->name,
 					     CGROUP_CREATE_RETRY, NULL);
@@ -1347,10 +1345,15 @@ __cgfsng_ops static inline bool cgfsng_payload_create(struct cgroup_ops *ops,
 					     CGROUP_CREATE_RETRY, NULL);
 	} else if (ops->cgroup_pattern) {
 		__cgroup_tree = lxc_string_replace("%n", handler->name, ops->cgroup_pattern);
+		if (!__cgroup_tree)
+			return ret_set_errno(false, ENOMEM);
+
 		cgroup_tree = __cgroup_tree;
-		container_cgroup = must_concat(&len, cgroup_tree,
+		container_cgroup = must_concat(&len, cgroup_tree, "/",
+					       DEFAULT_PAYLOAD_CGROUP,
 					       CGROUP_CREATE_RETRY, NULL);
 	} else {
+		cgroup_tree = NULL;
 		container_cgroup = must_concat(&len, DEFAULT_PAYLOAD_CGROUP_PREFIX,
 					     handler->name,
 					     CGROUP_CREATE_RETRY, NULL);

src/lxc/cgroups/cgroup.h

@@ -12,6 +12,8 @@
 #define DEFAULT_CGROUP_MOUNTPOINT "/sys/fs/cgroup"
 #define DEFAULT_PAYLOAD_CGROUP_PREFIX "lxc.payload."
 #define DEFAULT_MONITOR_CGROUP_PREFIX "lxc.monitor."
+#define DEFAULT_PAYLOAD_CGROUP "payload"
+#define DEFAULT_MONITOR_CGROUP "monitor"
 #define CGROUP_CREATE_RETRY "-NNNN"
 #define CGROUP_CREATE_RETRY_LEN (STRLITERALLEN(CGROUP_CREATE_RETRY))
 #define CGROUP_PIVOT "lxc.pivot"

src/lxc/initutils.c

@@ -169,8 +169,7 @@ const char *lxc_global_config_value(const char *option_name)
 				free(user_lxc_path);
 				user_lxc_path = copy_global_config_value(slider1);
 				remove_trailing_slashes(user_lxc_path);
-				values[i] = user_lxc_path;
-				user_lxc_path = NULL;
+				values[i] = move_ptr(user_lxc_path);
 				goto out;
 			}
 
@@ -182,19 +181,14 @@ const char *lxc_global_config_value(const char *option_name)
 	/* could not find value, use default */
 	if (strcmp(option_name, "lxc.lxcpath") == 0) {
 		remove_trailing_slashes(user_lxc_path);
-		values[i] = user_lxc_path;
-		user_lxc_path = NULL;
-	}
-	else if (strcmp(option_name, "lxc.default_config") == 0) {
-		values[i] = user_default_config_path;
-		user_default_config_path = NULL;
-	}
-	else if (strcmp(option_name, "lxc.cgroup.pattern") == 0) {
-		values[i] = user_cgroup_pattern;
-		user_cgroup_pattern = NULL;
-	}
-	else
+		values[i] = move_ptr(user_lxc_path);
+	} else if (strcmp(option_name, "lxc.default_config") == 0) {
+		values[i] = move_ptr(user_default_config_path);
+	} else if (strcmp(option_name, "lxc.cgroup.pattern") == 0) {
+		values[i] = move_ptr(user_cgroup_pattern);
+	} else {
 		values[i] = (*ptr)[1];
+	}
 
 	/* special case: if default value is NULL,
 	 * and there is no config, don't view that