From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751768Ab3EJLrm (ORCPT ); Fri, 10 May 2013 07:47:42 -0400 Received: from merlin.infradead.org ([205.233.59.134]:39003 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751369Ab3EJLrl (ORCPT ); Fri, 10 May 2013 07:47:41 -0400 Date: Fri, 10 May 2013 13:46:06 +0200 From: Peter Zijlstra To: Sasha Levin Cc: torvalds@linux-foundation.org, mingo@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 7/9] liblockdep: Support using LD_PRELOAD Message-ID: <20130510114605.GA32110@dyad.programming.kicks-ass.net> References: <1368115089-8909-1-git-send-email-sasha.levin@oracle.com> <1368115089-8909-8-git-send-email-sasha.levin@oracle.com> <20130510111719.GG31235@dyad.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130510111719.GG31235@dyad.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 10, 2013 at 01:17:19PM +0200, Peter Zijlstra wrote: > On Thu, May 09, 2013 at 11:58:07AM -0400, Sasha Levin wrote: > > + /* > > + * Some programs attempt to initialize and use locks in their > > + * allocation path. This means that a call to malloc() would > > + * result in locks being initialized and locked. > > + * > > + * Why is it an issue for us? dlsym() below will try allocating to > > + * give us the original function. Since this allocation will result > > + * in a locking operations, we have to let pthread deal with it, > > + * but we can't! we don't have the pointer to the original API > > + * since we're inside dlsym() trying to get it :( > > + * > > + * We can work around it by telling the program that locking was > > + * really okay, and just initialize those locks when we're fully > > + * up and running (this is ok because this all happens during > > + * initialization phase, when we have just one thread). But > > + * this is a big TODO at this point. > > + */ > > + if (preload_started) { > > + printf( > > + "LOCKDEP error: It seems that the program you are trying to " > > + "debug is initializing locks in it's allocation path.\n" > > + "This means that liblockdep cannot reliably analyze this " > > + "program since we need the allocator to work before we can " > > + "debug locks.\nSorry!\n"); > > + > > + exit(1); > > + } > > > Would something like the below cure things? Obviously this hasn't been near a > compiler for the entire thing still isn't wanting to compile for me. OK, that won't do indeed. Not being able to malloc is only part of the problem. /me goes stare at it more