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

Rafael J. Wysocki
2007-11-22T16:09:20Z

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