From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Graf Subject: Re: [PATCH 1/2] Traffic control cgroups subsystem Date: Thu, 11 Sep 2008 00:01:15 +0200 Message-ID: <20080910220115.GH20815@postel.suug.ch> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: davem@davemloft.net, akpm@linux-foundation.org, kaber@trash.net, lizf@cn.fujitsu.com, menage@google.com, linux-kernel@vger.kernel.org, netdev@vger.kernel.org To: Ranjit Manomohan Return-path: Received: from postel.suug.ch ([194.88.212.233]:42994 "EHLO postel.suug.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753117AbYIJWAz (ORCPT ); Wed, 10 Sep 2008 18:00:55 -0400 Content-Disposition: inline In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: * Ranjit Manomohan 2008-09-10 10:42 > +void cgroup_tc_set_sock_classid(struct sock *sk) > +{ > + if (sk) > + sk->sk_cgroup_classid = cgroup_tc_classid(current); > +} > + > @@ -1170,6 +1171,8 @@ static int __sock_create(struct net *net, int family, int type, int protocol, > if (err < 0) > goto out_module_put; > > + cgroup_tc_set_sock_classid(sock->sk); > + > /* > * Now to bump the refcnt of the [loadable] module that owns this > * socket at sock_release time we decrement its refcnt. > @@ -1444,6 +1447,8 @@ asmlinkage long sys_accept(int fd, struct sockaddr __user *upeer_sockaddr, > if (err < 0) > goto out_fd; > > + cgroup_tc_set_sock_classid(newsock->sk); > + > if (upeer_sockaddr) { > if (newsock->ops->getname(newsock, (struct sockaddr *)address, > &len, 2) < 0) { The big disadvantage of this method is that it does not allow to change the classid for sockets which already exist. It inherits the classid at socket creation time and then sticks to it. So if you want to follow this approach I'd suggest to at least store a reference to the cgroup state and reference count it properly. As for the locking that you mentioned in the other thread. IMHO it is not possible to lookup a socket without taking at least one lock, but I might be wrong there. Actually I think it will take even more locks as different locks are used to f.e. protect listening and established tcp sockets.