From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH] pkt_sched: Fix lockdep warning on est_tree_lock in gen_estimator Date: Thu, 02 Sep 2010 13:22:48 -0700 (PDT) Message-ID: <20100902.132248.229742285.davem@davemloft.net> References: <20100902201257.GA3089@del.dom.local> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: eric.dumazet@gmail.com, netdev@vger.kernel.org To: jarkao2@gmail.com Return-path: Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:55790 "EHLO sunset.davemloft.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751217Ab0IBUWc (ORCPT ); Thu, 2 Sep 2010 16:22:32 -0400 In-Reply-To: <20100902201257.GA3089@del.dom.local> Sender: netdev-owner@vger.kernel.org List-ID: From: Jarek Poplawski Date: Thu, 2 Sep 2010 22:12:58 +0200 > This patch fixes a lockdep warning: > > [ 516.287584] ========================================================= > [ 516.288386] [ INFO: possible irq lock inversion dependency detected ] > [ 516.288386] 2.6.35b #7 > [ 516.288386] --------------------------------------------------------- > [ 516.288386] swapper/0 just changed the state of lock: > [ 516.288386] (&qdisc_tx_lock){+.-...}, at: [] est_timer+0x62/0x1b4 > [ 516.288386] but this lock took another, SOFTIRQ-unsafe lock in the past: > [ 516.288386] (est_tree_lock){+.+...} > [ 516.288386] > [ 516.288386] and interrupts could create inverse lock ordering between them. > ... > > So, est_tree_lock needs BH protection because it's taken by > qdisc_tx_lock, which is used both in BH and process contexts. > (Full warning with this patch at netdev, 02 Sep 2010.) > > Fixes commit: ae638c47dc040b8def16d05dc6acdd527628f231 > > Signed-off-by: Jarek Poplawski Applied, thanks Jarek. Eric, please make an effort to run with lockdep enabled when making locking changes, just for fun :-)