linux-kernel - Re: [PATCH] iTCO_wdt: Don't double the requested timeout

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Message-ID: <20100225084535.4658cbf9@marrow.netinsight.se>
Date:	Thu, 25 Feb 2010 08:45:35 +0100
From:	Simon Kagstrom <simon.kagstrom@...insight.net>
To:	Pádraig Brady <P@...igBrady.com>
Cc:	Wim Van Sebroeck <wim@...ana.be>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iTCO_wdt: Don't double the requested timeout

(taking back lkml on CC. The discussion is about stopping watchdogs
before rebooting).

On Wed, 24 Feb 2010 16:10:00 +0000
Pádraig Brady <P@...igBrady.com> wrote:
> > Returning to the initial issue (my patch to avoid stopping the watchdog
> > before reboot): What is the preferred behavior? I've looked in other
> > drivers, and see multiple ways being used. Some do as in my patch, some
> > leave it on unconditionally and some stop it unconditionally.
> >
> Well nowayout to me means userspace should have no way out,
> but when rebooting the system the watchdog should be reset.
> But in saying that I'm not sure what to do. At least there
> should be some way to select the operation you want above,
> so as to protect the reboot process itself.

Well, from the drives I saw that had this behavior (not that I checked
all of them), they did look at nowayout to determine whether to stop it
or not.

> In general, I wonder could an order be specified so that
> the watchdog is disabled as the very last thing by the kernel,
> right before it does the reboot?

Many other drivers use reboot notifiers, but unfortunately it seems
that these are called before device shutdown (kernel/sys.c), so it
wouldn't help here.


I guess it would be good to have defined and uniform behavior across
different watchdogs, and at least an option to specify
nowayout-also-when-rebooting.

// Simon
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