linux-kernel - Re: [RESEND][PATCH v3] watchdog: Fix disable/enable regression

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Message-ID: <20121220191752.GR88797@redhat.com>
Date:	Thu, 20 Dec 2012 14:17:53 -0500
From:	Don Zickus <dzickus@...hat.com>
To:	Bjørn Mork <bjorn@...k.no>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org,
	Norbert Warmuth <nwarmuth@...nline.de>,
	Joseph Salisbury <joseph.salisbury@...onical.com>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [RESEND][PATCH v3] watchdog: Fix disable/enable regression

On Wed, Dec 19, 2012 at 10:44:44PM +0100, Bjørn Mork wrote:
> Bjørn Mork <bjorn@...k.no> writes:
> > Don Zickus <dzickus@...hat.com> writes:
> >
> >> What about the opposite cases?  
> >> nmi_watchdog=1
> >> echo 1 > /sys/devices/system/cpu/cpu1/online
> >
> > I don't see why not. But verifying it would be nice.  I thought that it
> > would be a simple thing to test using qemu-kvm, but it seems that the
> > CPU hotplugging support there isn't quite ready. The guest just dies
> > with "Assertion `bus->allow_hotplug' failed."
> >
> > I'll go digging for alternatives, but if anyone else could verify this
> > then I'd appreciate it.
> 
> I just realized that you might not really want/need hotplugging, but
> just booting with some cores initially offline?

Actually, I did a poor job explaining myself but your previous email
answered my question.

The original problem was that hrtimer_cancel was being called on an
un-initialized object.  I was wondering what happens if watchdog_enable
was called multiple times, would it re-initialize a new object causing a
memory leak?

But as you pointed out that couldn't happen.

So I am fine with your changes.  Thanks for the initial and follow up
testing.

Acked-by: Don Zickus <dzickus@...hat.com>
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