Re: [RFC PATCH 00/13] firmware loader: introduce cache/uncache firmware

From: Rafael J. Wysocki
Date: Wed Jul 25 2012 - 14:56:39 EST


On Wednesday, July 25, 2012, Linus Torvalds wrote:
> On Wed, Jul 25, 2012 at 5:35 AM, Ming Lei <ming.lei@xxxxxxxxxxxxx> wrote:
> >
> > The below patch should fix the problem above.
>
> Actually, I think we could make this even simpler.
>
> There's nothing wrong with saying "user mode is enabled" *just* before
> we unthaw things, if we also simply guarantee that there is no
> sleeping lock or similar that we might get caught on (causing a
> deadlock or other untimely waking) before we've actually thawed
> everything.
>
> So *if* the only problem wrt the USB hub code comes from this area,
> then I think the solution might be as simple as just moving the
> "usermodehelper_enable()" up a few lines, with a comment. Something
> like the *untested* and whitespace-damaged thing below..
>
> Rafael?

Yes, we can do this I think.

> Who has one of those isight things and has seen the warning to test?

That I can't answer, sorry.

Rafael


> ---
> diff --git a/kernel/power/process.c b/kernel/power/process.c
> index 19db29f67558..5bf50e488196 100644
> --- a/kernel/power/process.c
> +++ b/kernel/power/process.c
> @@ -181,6 +181,12 @@ void thaw_processes(void)
> pm_freezing = false;
> pm_nosig_freezing = false;
>
> + /*
> + * User mode helper are available again (or will be,
> + * modulo scheduling)
> + */
> + usermodehelper_enable();
> +
> oom_killer_enable();
>
> printk("Restarting tasks ... ");
> @@ -193,8 +199,6 @@ void thaw_processes(void)
> } while_each_thread(g, p);
> read_unlock(&tasklist_lock);
>
> - usermodehelper_enable();
> -
> schedule();
> printk("done.\n");
> }
>
>

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