[PATCH 2/14] uml: fix bad NTP interaction with clock

[PATCH 2/14] uml: fix bad NTP interaction with clock

[Jeff Dike]

>From 2b95eda726d565d4abe3cac045022d3141a11b23 Mon Sep 17 00:00:00 2001

UML's supposed nanosecond clock interacts badly with NTP when NTP
decides that the clock has drifted ahead and needs to be slowed down.
Slowing down the clock is done by decrementing the cycle-to-nanosecond
multiplier, which is 1.  Decrementing that gives you 0 and time is
stopped.

This is fixed by switching to a microsecond clock, with a multiplier
of 1000.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Cc: WANG Cong <xiyou.wangcong@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 arch/um/kernel/time.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/um/kernel/time.c b/arch/um/kernel/time.c
index e066e84..5036c81 100644
--- a/arch/um/kernel/time.c
+++ b/arch/um/kernel/time.c
@@ -74,7 +74,7 @@ static irqreturn_t um_timer(int irq, void *dev)
 
 static cycle_t itimer_read(void)
 {
-	return os_nsecs();
+	return os_nsecs() / 1000;
 }
 
 static struct clocksource itimer_clocksource = {
@@ -82,7 +82,7 @@ static struct clocksource itimer_clocksource = {
 	.rating		= 300,
 	.read		= itimer_read,
 	.mask		= CLOCKSOURCE_MASK(64),
-	.mult		= 1,
+	.mult		= 1000,
 	.shift		= 0,
 	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
 };
-- 
1.5.5.1

[PATCH 2/14] uml: fix bad NTP interaction with clock

[Jeff Dike]

>From cfd28f6695d0fc047478480791a21bdd4967f98e

UML's supposed nanosecond clock interacts badly with NTP when NTP
decides that the clock has drifted ahead and needs to be slowed down.
Slowing down the clock is done by decrementing the cycle-to-nanosecond
multiplier, which is 1.  Decrementing that gives you 0 and time is
stopped.

This is fixed by switching to a microsecond clock, with a multiplier
of 1000.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Cc: WANG Cong <xiyou.wangcong@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 arch/um/kernel/time.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/um/kernel/time.c b/arch/um/kernel/time.c
index e066e84..5036c81 100644
--- a/arch/um/kernel/time.c
+++ b/arch/um/kernel/time.c
@@ -74,7 +74,7 @@ static irqreturn_t um_timer(int irq, void *dev)
 
 static cycle_t itimer_read(void)
 {
-	return os_nsecs();
+	return os_nsecs() / 1000;
 }
 
 static struct clocksource itimer_clocksource = {
@@ -82,7 +82,7 @@ static struct clocksource itimer_clocksource = {
 	.rating		= 300,
 	.read		= itimer_read,
 	.mask		= CLOCKSOURCE_MASK(64),
-	.mult		= 1,
+	.mult		= 1000,
 	.shift		= 0,
 	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
 };
-- 
1.5.5.1

patch uml-fix-bad-ntp-interaction-with-clock.patch added to 2.6.25-stable tree

[gregkh]

This is a note to let you know that we have just queued up the patch titled

    Subject: uml: fix bad NTP interaction with clock

to the 2.6.25-stable tree.  Its filename is

    uml-fix-bad-ntp-interaction-with-clock.patch

A git repo of this tree can be found at 
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary


>From stable-bounces@linux.kernel.org Tue Aug  5 13:14:46 2008
From: Jeff Dike <jdike@addtoit.com>
Date: Tue, 5 Aug 2008 16:14:03 -0400
Subject: uml: fix bad NTP interaction with clock
To: stable@kernel.org
Cc: LKML <linux-kernel@vger.kernel.org>, uml-devel <user-mode-linux-devel@lists.sourceforge.net>
Message-ID: <20080805201403.GA11734@c2.user-mode-linux.org>
Content-Disposition: inline

From: Jeff Dike <jdike@addtoit.com>

commit cfd28f6695d0fc047478480791a21bdd4967f98e upstream

UML's supposed nanosecond clock interacts badly with NTP when NTP
decides that the clock has drifted ahead and needs to be slowed down.
Slowing down the clock is done by decrementing the cycle-to-nanosecond
multiplier, which is 1.  Decrementing that gives you 0 and time is
stopped.

This is fixed by switching to a microsecond clock, with a multiplier
of 1000.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Cc: WANG Cong <xiyou.wangcong@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 arch/um/kernel/time.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/arch/um/kernel/time.c
+++ b/arch/um/kernel/time.c
@@ -74,7 +74,7 @@ static irqreturn_t um_timer(int irq, voi
 
 static cycle_t itimer_read(void)
 {
-	return os_nsecs();
+	return os_nsecs() / 1000;
 }
 
 static struct clocksource itimer_clocksource = {
@@ -82,7 +82,7 @@ static struct clocksource itimer_clockso
 	.rating		= 300,
 	.read		= itimer_read,
 	.mask		= CLOCKSOURCE_MASK(64),
-	.mult		= 1,
+	.mult		= 1000,
 	.shift		= 0,
 	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
 };


Patches currently in stable-queue which might be from jdike@addtoit.com are

queue-2.6.25/uml-fix-build-when-slob-is-enabled.patch
queue-2.6.25/uml-fix-bad-ntp-interaction-with-clock.patch
queue-2.6.25/uml-physical-memory-shouldn-t-include-initial-stack.patch
queue-2.6.25/uml-track-and-make-up-lost-ticks.patch
queue-2.6.25/uml-missed-kmalloc-in-pcap_user.c.patch
queue-2.6.25/uml-deal-with-host-time-going-backwards.patch
queue-2.6.25/uml-deal-with-inaccessible-address-space-start.patch
queue-2.6.25/uml-missing-export-of-csum_partial-on-uml-amd64.patch
queue-2.6.25/uml-memcpy-export-needs-to-follow-host-declaration.patch
queue-2.6.25/uml-stub-needs-to-tolerate-sigwinch.patch
queue-2.6.25/uml-work-around-broken-host-ptrace_sysemu.patch
queue-2.6.25/uml-fix-gcc-ices-and-unresolved-externs.patch
queue-2.6.25/uml-fix-boot-crash.patch