From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Rafael J. Wysocki" <rjw@sisk.pl>
Subject: Re: [PATCH 1/2] Freezer: Fix s2disk resume from initrd
	(rev. 2)
Date: Thu, 22 Nov 2007 17:09:20 +0100
Message-ID: <200711221709.21175.rjw@sisk.pl>
References: <200711212322.02340.rjw@sisk.pl> <200711212325.32964.rjw@sisk.pl>
	<20071122095059.GA9860@elf.ucw.cz>
Mime-Version: 1.0
Content-Type: text/plain;
  charset="iso-8859-1"
Content-Transfer-Encoding: 7bit
Return-path: <linux-pm-bounces@lists.linux-foundation.org>
In-Reply-To: <20071122095059.GA9860@elf.ucw.cz>
Content-Disposition: inline
List-Unsubscribe: <https://lists.linux-foundation.org/mailman/listinfo/linux-pm>,
	<mailto:linux-pm-request@lists.linux-foundation.org?subject=unsubscribe>
List-Archive: <http://lists.linux-foundation.org/pipermail/linux-pm>
List-Post: <mailto:linux-pm@lists.linux-foundation.org>
List-Help: <mailto:linux-pm-request@lists.linux-foundation.org?subject=help>
List-Subscribe: <https://lists.linux-foundation.org/mailman/listinfo/linux-pm>,
	<mailto:linux-pm-request@lists.linux-foundation.org?subject=subscribe>
Sender: linux-pm-bounces@lists.linux-foundation.org
Errors-To: linux-pm-bounces@lists.linux-foundation.org
To: Pavel Machek <pavel@ucw.cz>
Cc: Nigel Cunningham <nigel@suspend2.net>, pm list <linux-pm@lists.linux-foundation.org>, Chris Friedhoff <chris@friedhoff.org>, Ingo Molnar <mingo@elte.hu>
List-Id: linux-pm@vger.kernel.org

On Thursday, 22 of November 2007, Pavel Machek wrote:
> Hi!
> 
> > Add appropriate freezer annotations to handle_initrd(), so that it's possible
> > to resume from disk from an initrd.
> > 
> > This patch fixes Bug #9345: http://bugzilla.kernel.org/show_bug.cgi?id=9345
> 
> 
> Unfortunately, bugzilla does not help me in understanding this.
> 
> > Index: linux-2.6/init/do_mounts_initrd.c
> > ===================================================================
> > --- linux-2.6.orig/init/do_mounts_initrd.c
> > +++ linux-2.6/init/do_mounts_initrd.c
> > @@ -55,12 +55,18 @@ static void __init handle_initrd(void)
> >  	sys_mount(".", "/", NULL, MS_MOVE, NULL);
> >  	sys_chroot(".");
> >  
> > +	/*
> > +	 * In case that a resume from disk is carried out by linuxrc or one of
> > +	 * its children, we need to tell the freezer not to wait for us.
> > +	 */
> > +	current->flags |= PF_FREEZER_SKIP;
> > +
> >  	pid = kernel_thread(do_linuxrc, "/linuxrc", SIGCHLD);
> >  	if (pid > 0)
> > -		while (pid != sys_wait4(-1, NULL, 0, NULL)) {
> > -			try_to_freeze();
> > +		while (pid != sys_wait4(-1, NULL, 0, NULL))
> >  			yield();
> > -		}
> > +
> > +	current->flags &= ~PF_FREEZER_SKIP;
> 
> New code should work (but it is uglier than the old one).

Well, the old code plain doesn't work ...

> What was wrong with the old one? Refrigerator should make sys_wait4() return,

It doesn't, because the task as no mm and is therefore considered as a kernel
thread and not sent a signal.

This _really_ is an exceptional case.

Greetings,
Rafael