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* Patch "hrtimer: Add support for CLOCK_MONOTONIC_RAW" has been added to the 4.4-stable tree
@ 2016-09-27 14:27 gregkh
  2016-09-27 16:12 ` Marc Zyngier
  0 siblings, 1 reply; 5+ messages in thread
From: gregkh @ 2016-09-27 14:27 UTC (permalink / raw)
  To: marc.zyngier, christoffer.dall, gregkh, nbd, tglx, tn
  Cc: stable, stable-commits


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>

---
 include/linux/hrtimer.h |    1 +
 kernel/time/hrtimer.c   |   11 ++++++++++-
 2 files changed, 11 insertions(+), 1 deletion(-)

--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -153,6 +153,7 @@ enum  hrtimer_base_type {
 	HRTIMER_BASE_REALTIME,
 	HRTIMER_BASE_BOOTTIME,
 	HRTIMER_BASE_TAI,
+	HRTIMER_BASE_MONOTONIC_RAW,
 	HRTIMER_MAX_CLOCK_BASES,
 };
 
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -90,6 +90,11 @@ DEFINE_PER_CPU(struct hrtimer_cpu_base,
 			.clockid = CLOCK_TAI,
 			.get_time = &ktime_get_clocktai,
 		},
+		{
+			.index = HRTIMER_BASE_MONOTONIC_RAW,
+			.clockid = CLOCK_MONOTONIC_RAW,
+			.get_time = &ktime_get_raw,
+		},
 	}
 };
 
@@ -99,6 +104,7 @@ static const int hrtimer_clock_to_base_t
 
 	[CLOCK_REALTIME]	= HRTIMER_BASE_REALTIME,
 	[CLOCK_MONOTONIC]	= HRTIMER_BASE_MONOTONIC,
+	[CLOCK_MONOTONIC_RAW]	= HRTIMER_BASE_MONOTONIC_RAW,
 	[CLOCK_BOOTTIME]	= HRTIMER_BASE_BOOTTIME,
 	[CLOCK_TAI]		= HRTIMER_BASE_TAI,
 };
@@ -1292,7 +1298,10 @@ static void __hrtimer_run_queues(struct
 		if (!(active & 0x01))
 			continue;
 
-		basenow = ktime_add(now, base->offset);
+		if (unlikely(base->index == HRTIMER_BASE_MONOTONIC_RAW))
+			basenow = ktime_get_raw();
+		else
+			basenow = ktime_add(now, base->offset);
 
 		while ((node = timerqueue_getnext(&base->active))) {
 			struct hrtimer *timer;


Patches currently in stable-queue which might be from marc.zyngier@arm.com are

queue-4.4/hrtimer-add-support-for-clock_monotonic_raw.patch

^ permalink raw reply	[flat|nested] 5+ messages in thread
end of thread, other threads:[~2016-09-27 20:06 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2016-09-27 14:27 Patch "hrtimer: Add support for CLOCK_MONOTONIC_RAW" has been added to the 4.4-stable tree gregkh
2016-09-27 16:12 ` Marc Zyngier
2016-09-27 18:03   ` Greg KH
2016-09-27 19:55     ` Felix Fietkau
2016-09-27 20:06       ` Johannes Berg

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