From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753017AbbEATlQ (ORCPT ); Fri, 1 May 2015 15:41:16 -0400 Received: from e37.co.us.ibm.com ([32.97.110.158]:34149 "EHLO e37.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751860AbbEATlH (ORCPT ); Fri, 1 May 2015 15:41:07 -0400 Date: Fri, 1 May 2015 12:41:02 -0700 From: "Paul E. McKenney" To: Rik van Riel Cc: Linux kernel Mailing List Subject: Re: RCU recursion? (code inspection) Message-ID: <20150501194102.GH5381@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <5543D184.4070707@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5543D184.4070707@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15050119-0025-0000-0000-00000A43CF56 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 01, 2015 at 03:18:28PM -0400, Rik van Riel wrote: > Hi Paul, > > While looking at synchronize_rcu(), I noticed that > synchronize_rcu_expedited() calls synchronize_sched_expedited(), > which can call synchronize_sched() when it is worried about > the counter wrapping, which can call synchronize_sched_expedited() > > The code is sufficiently convoluted that I am unsure whether this > recursion can actually happen in practice, but I also did not spot > anything that would stop it. Hmmm... Sounds like I should take a look! Thanx, Paul