From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [Patch net] net_sched: avoid generating same handle for u32 filters Date: Sun, 20 Jul 2014 20:49:53 -0700 (PDT) Message-ID: <20140720.204953.867212897376669839.davem@davemloft.net> References: <1405643693-4880-1-git-send-email-xiyou.wangcong@gmail.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, jhs@mojatatu.com, cwang@twopensource.com To: xiyou.wangcong@gmail.com Return-path: Received: from shards.monkeyblade.net ([149.20.54.216]:52899 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752449AbaGUDty (ORCPT ); Sun, 20 Jul 2014 23:49:54 -0400 In-Reply-To: <1405643693-4880-1-git-send-email-xiyou.wangcong@gmail.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Cong Wang Date: Thu, 17 Jul 2014 17:34:53 -0700 > From: Cong Wang > > When kernel generates a handle for a u32 filter, it tries to start > from the max in the bucket. So when we have a filter with the max (fff) > handle, it will cause kernel always generates the same handle for new > filters. This can be shown by the following command: > > tc qdisc add dev eth0 ingress > tc filter add dev eth0 parent ffff: protocol ip pref 770 handle 800::fff u32 match ip protocol 1 0xff > tc filter add dev eth0 parent ffff: protocol ip pref 770 u32 match ip protocol 1 0xff > ... > > we will get some u32 filters with same handle: > > # tc filter show dev eth0 parent ffff: > filter protocol ip pref 770 u32 > filter protocol ip pref 770 u32 fh 800: ht divisor 1 > filter protocol ip pref 770 u32 fh 800::fff order 4095 key ht 800 bkt 0 > match 00010000/00ff0000 at 8 > filter protocol ip pref 770 u32 fh 800::fff order 4095 key ht 800 bkt 0 > match 00010000/00ff0000 at 8 > filter protocol ip pref 770 u32 fh 800::fff order 4095 key ht 800 bkt 0 > match 00010000/00ff0000 at 8 > filter protocol ip pref 770 u32 fh 800::fff order 4095 key ht 800 bkt 0 > match 00010000/00ff0000 at 8 > > handles should be unique. This patch fixes it by looking up a bitmap, > so that can guarantee the handle is as unique as possible. For compatibility, > we still start from 0x800. > > Cc: "David S. Miller" > Cc: Jamal Hadi Salim > Signed-off-by: Cong Wang > Signed-off-by: Cong Wang Applied, thank you.