From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexander Duyck Subject: Re: [Patch net-next] fib: move fib_rules_cleanup_ops() under rtnl lock Date: Thu, 26 Mar 2015 16:47:37 -0700 Message-ID: <55149A99.6040704@redhat.com> References: <1427403769-31208-1-git-send-email-xiyou.wangcong@gmail.com> <55147E5D.2070600@redhat.com> <55148576.1010303@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Cong Wang , netdev , tgraf@suug.ch To: Cong Wang Return-path: Received: from mx1.redhat.com ([209.132.183.28]:39983 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753416AbbCZXri (ORCPT ); Thu, 26 Mar 2015 19:47:38 -0400 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On 03/26/2015 04:05 PM, Cong Wang wrote: > On Thu, Mar 26, 2015 at 3:32 PM, Cong Wang wrote: >> On the other hand, the name rules_mod_lock already tells it is >> just a protection for ops (module) register. > I even doubt we really need rules_mod_lock, it is per netns, > which is newly allocated when registering pernet and upper > layer should guarantee no concurrent unregistering, so we > probably only need to take rtnl lock. I'm adding Thomas as he was the original author for the code and might have a better idea of what needs to be rtnl locked and what doesn't. You should probably CC him as well on the v2 patch. As far as why I am so focused on moving fib4_rules_exit it is because we don't want to call that delete function until after the table has been cleared. Otherwise you end up triggering the external_flush and unmerge code on a full table instead of an empty one. The result is you end up allocating a bunch of memory before you then turn around and free it. So even if you retain the rtnl_lock changes it would still be best to move fib4_rules_exit call to the region after you have freed the FIB tables, but before you free fib_table_hash. - Alex