Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932478AbZJELvk (ORCPT ); Mon, 5 Oct 2009 07:51:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932435AbZJELvk (ORCPT ); Mon, 5 Oct 2009 07:51:40 -0400 Received: from www.tglx.de ([62.245.132.106]:52407 "EHLO www.tglx.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932434AbZJELvj (ORCPT ); Mon, 5 Oct 2009 07:51:39 -0400 Date: Mon, 5 Oct 2009 13:50:46 +0200 (CEST) From: Thomas Gleixner To: Ingo Molnar cc: Peter Zijlstra , Anirban Sinha , linux-kernel@vger.kernel.org, Darren Hart , Kaz Kylheku , Anirban Sinha Subject: Re: futex question In-Reply-To: <20091005111933.GA25889@elte.hu> Message-ID: References: <20091001092218.GH15345@elte.hu> <4AC68F13.8050601@us.ibm.com> <4AC8CF32.8060108@anirban.org> <1254738974.26976.24.camel@twins> <1254741372.26976.35.camel@twins> <20091005111933.GA25889@elte.hu> User-Agent: Alpine 2.00 (LFD 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1635 Lines: 58 On Mon, 5 Oct 2009, Ingo Molnar wrote: > * Peter Zijlstra wrote: > > > diff --git a/fs/exec.c b/fs/exec.c > > index d49be6b..0812ba6 100644 > > --- a/fs/exec.c > > +++ b/fs/exec.c > > @@ -1295,6 +1295,22 @@ int do_execve(char * filename, > > bool clear_in_exec; > > int retval; > > > > + retval = -EWOULDBLOCK; > > +#ifdef CONFIG_FUTEX > > + if (unlikely(current->robust_list)) > > + goto out_ret; > > +#ifdef CONFIG_COMPAT > > + if (unlikely(current->compat_robust_list)) > > + goto out_ret; > > +#endif > > + spin_lock_irq(¤t->pi_lock); > > + if (!list_empty(¤t->pi_state_list)) { > > + spin_unlock_irq(¤t->pi_lock); > > + goto out_ret; > > + } > > + spin_unlock_irq(¤t->pi_lock); > > +#endif > > i suspect this should have the form of: > > retval = can_exec_robust_futexes(); > if (retval) > goto out_ret Yes. > retval = unshare_files(&displaced); > if (retval) > goto out_ret; > > ... > > but ... shouldnt we just do what exec normally does and zap any state > that shouldnt be carried over into the new context - instead of denying > the exec? Am i missing something? We want to check whether the robust list is empty. If it's not empty then we deny the exec instead of silently releasing the futexes or just ignoring the robust list entirely. Same applies for the pi waiters list. Thanks, tglx -- 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/