make cgmanager follow lxc.cgroup.use

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 7dddb89dedf7d2572d2442efb036d3b0845662ff..95f540f6244351a14ab5f9bb013aad492c2d2238 100644 (file)
--- a/src/lxc/cgmanager.c
+++ b/src/lxc/cgmanager.c
@@ -1093,6 +1093,76 @@ static void cull_user_controllers(void)
        }
 }
 
+static bool in_comma_list(const char *inword, const char *cgroup_use)
+{
+       char *e;
+       size_t inlen = strlen(inword), len;
+
+       do {
+               e = strchr(cgroup_use, ',');
+               len = e ? e - cgroup_use : strlen(cgroup_use);
+               if (len == inlen && strncmp(inword, cgroup_use, len) == 0)
+                       return true;
+               cgroup_use = e + 1;
+       } while (e);
+
+       return false;
+}
+
+static bool in_subsystem_list(const char *c)
+{
+       int i;
+
+       for (i = 0; i < nr_subsystems; i++) {
+               if (strcmp(c, subsystems[i]) == 0)
+                       return true;
+       }
+
+       return false;
+}
+
+/*
+ * If /etc/lxc/lxc.conf specifies lxc.cgroup.use = "freezer,memory",
+ * then clear out any other subsystems, and make sure that freezer
+ * and memory are both enabled
+ */
+static bool verify_and_prune(const char *cgroup_use)
+{
+       const char *p;
+       char *e;
+       int i, j;
+
+       for (p = cgroup_use; p && *p; p = e + 1) {
+               e = strchr(p, ',');
+               if (e)
+                       *e = '\0';
+
+               if (!in_subsystem_list(p)) {
+                       ERROR("Controller %s required by lxc.cgroup.use but not available\n", p);
+                       return false;
+               }
+
+               if (e)
+                       *e = ',';
+               if (!e)
+                       break;
+       }
+
+       for (i = 0; i < nr_subsystems;) {
+               if (in_comma_list(subsystems[i], cgroup_use)) {
+                       i++;
+                       continue;
+               }
+               free(subsystems[i]);
+               for (j = i;  j < nr_subsystems-1; j++)
+                       subsystems[j] = subsystems[j+1];
+               subsystems[nr_subsystems-1] = NULL;
+               nr_subsystems--;
+       }
+
+       return true;
+}
+
 static bool collect_subsytems(void)
 {
        char *line = NULL;
@@ -1154,6 +1224,18 @@ static bool collect_subsytems(void)
                return false;
        }
 
+       /* make sure that cgroup.use can be and is honored */
+       const char *cgroup_use = lxc_global_config_value("lxc.cgroup.use");
+       if (!cgroup_use && errno != 0)
+               goto out_good;
+       if (cgroup_use) {
+               if (!verify_and_prune(cgroup_use))
+                       goto out_free;
+               subsystems_inone[0] = NIH_MUST( strdup(cgroup_use) );
+               cgm_all_controllers_same = false;
+       }
+
+out_good:
        return true;
 
 out_free: