linux-kernel - Re: [BUG REPORT] ktime_get

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Message-ID: <alpine.DEB.2.11.1601201837300.3575@nanos>
Date:	Wed, 20 Jan 2016 18:42:23 +0100 (CET)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	John Stultz <john.stultz@...aro.org>
cc:	Jeff Merkey <linux.mdb@...il.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [BUG REPORT] ktime_get_ts64 causes Hard Lockup

On Wed, 20 Jan 2016, John Stultz wrote:
> Ehrm.  A more productive route in solving this might be to cap the
> cycle delta we return from timekeeping_get_delta().
> 
> We already do this in the CONFIG_DEBUG_TIMEKEEPING, but adding a
> simple check it to the non-debug case should be doable w/o adding too
> much overhead to this very hot path.
> 
> Something like:
> if (delta > tkr->clock->max_cycles)
>     delta = tkr->clock->max_cycles;
> 
> return delta;

Well, you can make CONFIG_KDB select CONFIG_DEBUG_TIMEKEEPING.

Thanks,

	tglx