Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934045Ab3CZNTj (ORCPT ); Tue, 26 Mar 2013 09:19:39 -0400 Received: from 173-166-109-252-newengland.hfc.comcastbusiness.net ([173.166.109.252]:35101 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933294Ab3CZNTj (ORCPT ); Tue, 26 Mar 2013 09:19:39 -0400 Message-ID: <1364303965.5053.29.camel@laptop> Subject: Re: [PATCH -mm -next] ipc,sem: fix lockdep false positive From: Peter Zijlstra To: Michel Lespinasse Cc: Rik van Riel , Sasha Levin , torvalds@linux-foundation.org, davidlohr.bueso@hp.com, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, hhuang@redhat.com, jason.low2@hp.com, lwoodman@redhat.com, chegu_vinod@hp.com, Dave Jones , benisty.e@gmail.com, Ingo Molnar Date: Tue, 26 Mar 2013 14:19:25 +0100 In-Reply-To: References: <1363809337-29718-1-git-send-email-riel@surriel.com> <5150B1C2.8090607@oracle.com> <20130325163844.042a45ba@annuminas.surriel.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.6.2-0ubuntu0.1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1203 Lines: 31 On Mon, 2013-03-25 at 14:42 -0700, Michel Lespinasse wrote: > depth nesting here... > Adding Peter & Ingo for advice about how to proceed > > +++ b/ipc/sem.c > > @@ -357,7 +357,7 @@ static inline int sem_lock(struct sem_array > *sma, struct sembuf *sops, > > spin_lock(&sma->sem_perm.lock); > > for (i = 0; i < sma->sem_nsems; i++) { > > struct sem *sem = sma->sem_base + i; > > - spin_lock(&sem->lock); > > + spin_lock_nested(&sem->lock, > SINGLE_DEPTH_NESTING); > > } > > locknum = -1; > > } Right, so as walken said, this isn't going to work right. I need a little more information as I've not really paid much attention to this stuff. Firstly, is there a limit to sem_nsems or is this a random user specified number? Secondly do we care about lock order at all, or is array order the only order that counts? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/