Use 'cgm listcontrollers' list rather than /proc/self/cgroups

to populate the list of subsystems to use.

Cgmanager can be started with some subsystems disabled (i.e.
cgmanager -M cpuset).  If lxc using cgmanager then uses the
/proc/self/cgroup output to determine which controllers to use,
it will fail when trying to do things to cpuset.  Instead, ask
cgmanager which controllers to use.

This still defers (per patch 1/1) to the lxc.cgroup.use values.

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

diff --git a/src/lxc/cgmanager.c b/src/lxc/cgmanager.c
index 95f540f6244351a14ab5f9bb013aad492c2d2238..48b81d9dc1d64449b1c822e45bed1bd74004affa 100644 (file)
--- a/src/lxc/cgmanager.c
+++ b/src/lxc/cgmanager.c
@@ -818,6 +818,25 @@ out:
        return pids_len;
 }
 
+static bool lxc_list_controllers(char ***list)
+{
+       if (!cgm_dbus_connect()) {
+               ERROR("Error connecting to cgroup manager");
+               return false;
+       }
+       if (cgmanager_list_controllers_sync(NULL, cgroup_manager, list) != 0) {
+               NihError *nerr;
+               nerr = nih_error_get();
+               ERROR("call to cgmanager_list_controllers_sync failed: %s", nerr->message);
+               nih_free(nerr);
+               cgm_dbus_disconnect();
+               return false;
+       }
+
+       cgm_dbus_disconnect();
+       return true;
+}
+
 static inline void free_abs_cgroup(char *cgroup)
 {
        if (!cgroup)
@@ -1166,8 +1185,9 @@ static bool verify_and_prune(const char *cgroup_use)
 static bool collect_subsytems(void)
 {
        char *line = NULL;
+       nih_local char **cgm_subsys_list = NULL;
        size_t sz = 0;
-       FILE *f;
+       FILE *f = NULL;
 
        if (subsystems) // already initialized
                return true;
@@ -1178,6 +1198,20 @@ static bool collect_subsytems(void)
        subsystems_inone[0] = "all";
        subsystems_inone[1] = NULL;
 
+       if (lxc_list_controllers(&cgm_subsys_list)) {
+               while (cgm_subsys_list[nr_subsystems]) {
+                       char **tmp = NIH_MUST( realloc(subsystems,
+                                               (nr_subsystems+2)*sizeof(char *)) );
+                       tmp[nr_subsystems] = NIH_MUST(
+                                       strdup(cgm_subsys_list[nr_subsystems++]) );
+                       subsystems = tmp;
+               }
+               if (nr_subsystems)
+                       subsystems[nr_subsystems] = NULL;
+               goto collected;
+       }
+
+       INFO("cgmanager_list_controllers failed, falling back to /proc/self/cgroups");
        f = fopen_cloexec("/proc/self/cgroup", "r");
        if (!f) {
                f = fopen_cloexec("/proc/1/cgroup", "r");
@@ -1219,6 +1253,8 @@ static bool collect_subsytems(void)
        fclose(f);
 
        free(line);
+
+collected:
        if (!nr_subsystems) {
                ERROR("No cgroup subsystems found");
                return false;
@@ -1240,7 +1276,8 @@ out_good:
 
 out_free:
        free(line);
-       fclose(f);
+       if (f)
+               fclose(f);
        free_subsystems();
        return false;
 }