cgroup: don't set clone_children when it is already 1

In particular, if it's already 1, and we can't change it, we currently
fail out.  That's silly.

I was going to just always continue, but if clone_children is not 1,
then the container *will* fail to start later on, so I'd rather stop
earlier on so the original cause doesn't get lost in the noise.

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>

diff --git a/src/lxc/cgroup.c b/src/lxc/cgroup.c
index 8be0ebf42dbf41b73739047dcc5fb10b3229003a..f2a686a32a533474d33b1a8495749da5f38a7db1 100644 (file)
--- a/src/lxc/cgroup.c
+++ b/src/lxc/cgroup.c
@@ -1944,6 +1944,7 @@ int count_lines(const char *fn)
 int handle_cgroup_settings(struct cgroup_mount_point *mp, char *cgroup_path)
 {
        int r, saved_errno = 0;
+       char buf[2];
 
        /* If this is the memory cgroup, we want to enforce hierarchy.
         * But don't fail if for some reason we can't.
@@ -1951,9 +1952,12 @@ int handle_cgroup_settings(struct cgroup_mount_point *mp, char *cgroup_path)
        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_write_to_file(cc_path, "1", 1, false);
-                       if (r < 0)
-                               SYSERROR("failed to set memory.use_hiararchy to 1; continuing");
+                       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");
+                       }
                        free(cc_path);
                }
        }
@@ -1966,6 +1970,11 @@ int handle_cgroup_settings(struct cgroup_mount_point *mp, char *cgroup_path)
                char *cc_path = cgroup_to_absolute_path(mp, cgroup_path, "/cgroup.clone_children");
                if (!cc_path)
                        return -1;
+               r = lxc_read_from_file(cc_path, buf, 1);
+               if (r == 1 && buf[0] == '1') {
+                       free(cc_path);
+                       return 0;
+               }
                r = lxc_write_to_file(cc_path, "1", 1, false);
                saved_errno = errno;
                free(cc_path);