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Date: Tue, 27 Sep 2016 17:12:12 +0100
From: Marc Zyngier <marc.zyngier@arm.com>
To: <gregkh@linuxfoundation.org>
Cc: <christoffer.dall@linaro.org>, <nbd@nbd.name>,
        <tglx@linutronix.de>, <tn@semihalf.com>, <stable@vger.kernel.org>,
        <stable-commits@vger.kernel.org>
Subject: Re: Patch "hrtimer: Add support for CLOCK_MONOTONIC_RAW" has been
 added to the 4.4-stable tree
Message-ID: <20160927171212.2e75bb99@arm.com>
In-Reply-To: <1474986477241162@kroah.com>
References: <1474986477241162@kroah.com>
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Greg,

On Tue, 27 Sep 2016 16:27:57 +0200
<gregkh@linuxfoundation.org> wrote:

> This is a note to let you know that I've just added the patch titled
> 
>     hrtimer: Add support for CLOCK_MONOTONIC_RAW
> 
> to the 4.4-stable tree which can be found at:
>     http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
> 
> The filename of the patch is:
>      hrtimer-add-support-for-clock_monotonic_raw.patch
> and it can be found in the queue-4.4 subdirectory.
> 
> If you, or anyone else, feels it should not be added to the stable tree,
> please let <stable@vger.kernel.org> know about it.
> 
> 
> From 9c808765e88efb6fa6af7e2206ef89512f1840a7 Mon Sep 17 00:00:00 2001
> From: Marc Zyngier <marc.zyngier@arm.com>
> Date: Fri, 15 Jan 2016 17:41:08 +0000
> Subject: hrtimer: Add support for CLOCK_MONOTONIC_RAW
> 
> From: Marc Zyngier <marc.zyngier@arm.com>
> 
> commit 9c808765e88efb6fa6af7e2206ef89512f1840a7 upstream.
> 
> The KVM/ARM timer implementation arms a hrtimer when a vcpu is
> blocked (usually because it is waiting for an interrupt)
> while its timer is going to kick in the future.
> 
> It is essential that this timer doesn't get adjusted, or the
> guest will end up being woken-up at the wrong time (NTP running
> on the host seems to confuse the hell out of some guests).
> 
> In order to allow this, let's add CLOCK_MONOTONIC_RAW support
> to hrtimer (it is so far only supported for posix timers). It also
> has the (limited) benefit of fixing de0421d53bfb ("mac80211_hwsim:
> shuffle code to prepare for dynamic radios"), which already uses
> this functionnality without realizing wasn't implemented (just being
> lucky...).
> 
> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
> Cc: Tomasz Nowicki <tn@semihalf.com>
> Cc: Christoffer Dall <christoffer.dall@linaro.org>
> Link: http://lkml.kernel.org/r/1452879670-16133-2-git-send-email-marc.zyngier@arm.com
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Cc: Felix Fietkau <nbd@nbd.name>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Please drop that patch. It is utterly broken, and was reverted in
mainline with commit 82e88ff1ea94 ("hrtimer: Revert CLOCK_MONOTONIC_RAW
support").

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny.