Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030410AbXBZS2m (ORCPT ); Mon, 26 Feb 2007 13:28:42 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030393AbXBZS2m (ORCPT ); Mon, 26 Feb 2007 13:28:42 -0500 Received: from ogre.sisk.pl ([217.79.144.158]:32920 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030408AbXBZS2l (ORCPT ); Mon, 26 Feb 2007 13:28:41 -0500 From: "Rafael J. Wysocki" To: "Aneesh Kumar" Subject: Re: [RFC][PATCH 3/3] Freezer: Prevent ___call_usermodehelper from missing freezing requests Date: Mon, 26 Feb 2007 19:30:55 +0100 User-Agent: KMail/1.9.5 Cc: LKML , "Andrew Morton" , "Oleg Nesterov" , "Pavel Machek" , "Srivatsa Vaddagiri" , "Paul E. McKenney" , "Gautham R Shenoy" References: <200702261139.59130.rjw@sisk.pl> <200702261152.18379.rjw@sisk.pl> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200702261930.56550.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2279 Lines: 60 On Monday, 26 February 2007 12:58, Aneesh Kumar wrote: > On 2/26/07, Rafael J. Wysocki wrote: > > NOTE: Alternatively, we can just drop flush_signals() from there, but I'm not > > sure that's the right thing to do. > > > > --- > > From: Rafael J. Wysocki > > > > Since ____call_usermodehelper() calls flush_signals(current), the task that > > enters it may miss a freezing request. However, if ____call_usermodehelper() > > clears TIF_FREEZE for the current task after flush_signals(current) returns, the > > freezer will generate one more freezing request for this task. > > > > Signed-off-by: Rafael J. Wysocki > > --- > > kernel/kmod.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > Index: linux-2.6.20-mm2/kernel/kmod.c > > =================================================================== > > --- linux-2.6.20-mm2.orig/kernel/kmod.c 2007-02-25 12:07:15.000000000 +0100 > > +++ linux-2.6.20-mm2/kernel/kmod.c 2007-02-25 12:49:16.000000000 +0100 > > @@ -34,6 +34,7 @@ > > #include > > #include > > #include > > +#include > > #include > > > > extern int delete_module(const char *name, unsigned int flags); > > @@ -258,6 +259,7 @@ static int ____call_usermodehelper(void > > new_session = key_get(sub_info->ring); > > flush_signals(current); > > spin_lock_irq(¤t->sighand->siglock); > > + do_not_freeze(current); > > old_session = __install_session_keyring(current, new_session); > > flush_signal_handlers(current, 1); > > sigemptyset(¤t->blocked); > > > > > this need a comment . Otherwise one reading will read it as we don't > want it to freeze. > > How about > /* > clears TIF_FREEZE for the current task after flush_signals(current) > returns, so that the > freezer will generate one more freezing request for this task. > > */ Looks reasonable, but Oleg wants to drop the flush_signals(current) ... Rafael - 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/