linux-kernel - Re: [PATCH 06/10] time: Cap clocksource reads to the clocksource max

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Message-ID: <20150111124146.GA15387@localhost.localdomain>
Date:	Sun, 11 Jan 2015 13:41:46 +0100
From:	Richard Cochran <richardcochran@...il.com>
To:	John Stultz <john.stultz@...aro.org>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Dave Jones <davej@...emonkey.org.uk>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Prarit Bhargava <prarit@...hat.com>,
	Stephen Boyd <sboyd@...eaurora.org>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH 06/10] time: Cap clocksource reads to the clocksource
 max_cycles value

On Fri, Jan 09, 2015 at 04:34:24PM -0800, John Stultz wrote:
> When calculating the current delta since the last tick, we
> currently have no hard protections to prevent a multiplciation
> overflow from ocurring.

This is just papering over the problem. The "hard protection" should
be having a tick scheduled before the range of the clock source is
exhausted.

Thanks,
Richard
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