From: Thomas Gleixner <tglx@linutronix.de>
Date: Mon, 12 Sep 2011 11:32:23 +0000 (+0200)
Subject: clocksource: Make watchdog reset lockless
X-Git-Tag: v3.2-rc1~160^2~5
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9fb60336253edf73dedc527b2aa2bf32eae0d6da;p=pandora-kernel.git

clocksource: Make watchdog reset lockless

KGDB needs to trylock watchdog_lock when trying to reset the
clocksource watchdog after the system has been stopped to avoid a
potential deadlock. When the trylock fails TSC usually becomes
unstable.

We can be more clever by using an atomic counter and checking it in
the clocksource_watchdog callback. We restart the watchdog whenever
the counter is > 0 and only decrement the counter when we ran through
a full update cycle.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <johnstul@us.ibm.com>
Acked-by: Jason Wessel <jason.wessel@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1109121326280.2723@ionos
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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