Re: [PATCH 1/2] Freezer: Fix s2disk resume from initrd (rev. 2)

["Rafael J. Wysocki" <rjw@sisk.pl>]

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