cgroup.c: clean up for handle_cgroup_settings

Clean up the nesting if, make the logic similar for memory
and cpuset, and the error message should sent from inside,
for better extendibility.

Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>

src/lxc/cgroup.c

@@ -848,10 +848,8 @@ struct cgroup_process_info *lxc_cgroupfs_create(const char *name, const char *pa
 
 		if (lxc_string_in_array("ns", (const char **)h->subsystems))
 			continue;
-		if (handle_cgroup_settings(mp, info_ptr->cgroup_path) < 0) {
-			ERROR("Could not set clone_children to 1 for cpuset hierarchy in parent cgroup.");
+		if (handle_cgroup_settings(mp, info_ptr->cgroup_path) < 0)
 			goto out_initial_error;
-		}
 	}
 
 	/* normalize the path */
@@ -2084,47 +2082,66 @@ static int handle_cgroup_settings(struct cgroup_mount_point *mp,
 {
 	int r, saved_errno = 0;
 	char buf[2];
+	const char **subsystems = (const char **)mp->hierarchy->subsystems;
 
 	/* If this is the memory cgroup, we want to enforce hierarchy.
 	 * But don't fail if for some reason we can't.
 	 */
-	if (lxc_string_in_array("memory", (const char **)mp->hierarchy->subsystems)) {
-		char *cc_path = cgroup_to_absolute_path(mp, cgroup_path, "/memory.use_hierarchy");
-		if (cc_path) {
-			r = lxc_read_from_file(cc_path, buf, 1);
-			if (r < 1 || buf[0] != '1') {
-				r = lxc_write_to_file(cc_path, "1", 1, false);
-				if (r < 0)
-					SYSERROR("failed to set memory.use_hiararchy to 1; continuing");
-			}
+	if (lxc_string_in_array("memory", subsystems)) {
+		char *cc_path = cgroup_to_absolute_path(mp, cgroup_path,
+						"/memory.use_hierarchy");
+		if (!cc_path)
+			goto cpuset;
+
+		r = lxc_read_from_file(cc_path, buf, 1);
+		if (r == 1 && buf[0] == '1') {
 			free(cc_path);
+			goto cpuset;
 		}
-	}
+
+		r = lxc_write_to_file(cc_path, "1", 1, false);
+		if (r < 0)
+			SYSERROR("Failed to set memory.use_hiararchy to 1; continuing");
+		free(cc_path);
+ 	}
 
 	/* if this is a cpuset hierarchy, we have to set cgroup.clone_children in
 	 * the base cgroup, otherwise containers will start with an empty cpuset.mems
 	 * and cpuset.cpus and then
 	 */
-	if (lxc_string_in_array("cpuset", (const char **)mp->hierarchy->subsystems)) {
-		char *cc_path = cgroup_to_absolute_path(mp, cgroup_path, "/cgroup.clone_children");
+cpuset:
+	if (lxc_string_in_array("cpuset", subsystems)) {
 		struct stat sb;
+		char *cc_path = cgroup_to_absolute_path(mp, cgroup_path,
+						"/cgroup.clone_children");
 
 		if (!cc_path)
-			return -1;
-		if (stat(cc_path, &sb) != 0 && errno == ENOENT)
-			return 0;
+			goto err;
+		if (stat(cc_path, &sb) != 0 && errno == ENOENT) {
+			free(cc_path);
+			goto out;
+		}
+
 		r = lxc_read_from_file(cc_path, buf, 1);
 		if (r == 1 && buf[0] == '1') {
 			free(cc_path);
-			return 0;
+			goto out;
 		}
+
 		r = lxc_write_to_file(cc_path, "1", 1, false);
-		saved_errno = errno;
-		free(cc_path);
-		errno = saved_errno;
-		return r < 0 ? -1 : 0;
+		if (r < 0) {
+			SYSERROR("Failed to set clone_children to 1 for cpuset hierarchy in parent cgroup.");
+			saved_errno = errno;
+			free(cc_path);
+			errno = saved_errno;
+			goto err;
+		}
+ 		free(cc_path);
 	}
+out:
 	return 0;
+err:
+	return -1;
 }
 
 extern void lxc_monitor_send_state(const char *name, lxc_state_t state,