cgmanager: attach: never use 'all' controller

We were using 'all' controller if current was in all the
same cgroup.  That doesn't suffice.  We'd have to check
the target.  At that point we may as well just attach
controller by controller.

An optimization to consider is to check the /proc/initpid/cgroup
for all identical controllers.  Let's start by just getting it
right.

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

src/lxc/cgmanager.c

@@ -1430,16 +1430,8 @@ static bool cgm_attach(const char *name, const char *lxcpath, pid_t pid)
 		return false;
 	}
 
-	check_supports_multiple_controllers(pid);
-
-	if (cgm_all_controllers_same)
-		slist = subsystems_inone;
-
 	for (i = 0; slist[i]; i++) {
-		if (slist == subsystems_inone)
-			cgroup = try_get_abs_cgroup(name, lxcpath, subsystems[0]);
-		else
-			cgroup = try_get_abs_cgroup(name, lxcpath, slist[i]);
+		cgroup = try_get_abs_cgroup(name, lxcpath, slist[i]);
 		if (!cgroup) {
 			ERROR("Failed to get cgroup for controller %s", slist[i]);
 			cgm_dbus_disconnect();