From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933683Ab2DLBNt (ORCPT ); Wed, 11 Apr 2012 21:13:49 -0400 Received: from shards.monkeyblade.net ([198.137.202.13]:60602 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933296Ab2DLBNr (ORCPT ); Wed, 11 Apr 2012 21:13:47 -0400 Date: Wed, 11 Apr 2012 21:08:43 -0400 (EDT) Message-Id: <20120411.210843.716144028821174908.davem@davemloft.net> To: paulmck@linux.vnet.ibm.com Cc: shemminger@vyatta.com, mroos@linux.ee, linux-kernel@vger.kernel.org, netdev@vger.kernel.org Subject: Re: suspicious RCU usage warnings in 3.3.0 From: David Miller In-Reply-To: <20120412004507.GF2473@linux.vnet.ibm.com> References: <20120411171004.016ddd95@nehalam.linuxnetplumber.net> <20120411.201854.1070083308359208025.davem@davemloft.net> <20120412004507.GF2473@linux.vnet.ibm.com> X-Mailer: Mew version 6.4 on Emacs 23.3 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.2.6 (shards.monkeyblade.net [198.137.202.13]); Wed, 11 Apr 2012 18:08:45 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Paul E. McKenney" Date: Wed, 11 Apr 2012 17:45:07 -0700 > If I am confused about the simple function call, and if control is really > passing via an interrupt or exception, then rcu_irq_enter() should be > called on entry to the interrupt or exception and rcu_irq_exit() should > be called on exit. Hmm, it seems the convention changed such that platforms aren't supposed to invoke do_softirq() from their trap return trap any more. It's handled completely by irq_exit(). When did that start happening? :-) Anyways I bet that's the problem, sparc64 invokes do_softirq() in it's trap return path if softirqs are pending, and that doesn't do any of the RCU frobbing you mention.