lkml.org 
[lkml]   [2012]   [Mar]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[34-longterm 182/196] clocksource: Install completely before selecting
Date
From: john stultz <johnstul@us.ibm.com>

-------------------
This is a commit scheduled for the next v2.6.34 longterm release.
If you see a problem with using this for longterm, please comment.
-------------------

commit e05b2efb82596905ebfe88e8612ee81dec9b6592 upstream.

Christian Hoffmann reported that the command line clocksource override
with acpi_pm timer fails:

Kernel command line: <SNIP> clocksource=acpi_pm
hpet clockevent registered
Switching to clocksource hpet
Override clocksource acpi_pm is not HRT compatible.
Cannot switch while in HRT/NOHZ mode.

The watchdog code is what enables CLOCK_SOURCE_VALID_FOR_HRES, but we
actually end up selecting the clocksource before we enqueue it into
the watchdog list, so that's why we see the warning and fail to switch
to acpi_pm timer as requested. That's particularly bad when we want to
debug timekeeping related problems in early boot.

Put the selection call last.

[PG: 34 doesn't have __clocksource_register_scale, so drop that 1/2]

Reported-by: Christian Hoffmann <email@christianhoffmann.info>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Link: http://lkml.kernel.org/r/%3C1304558210.2943.24.camel%40work-vm%3E
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
kernel/time/clocksource.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index 1f5dde6..db24c5c 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -638,8 +638,8 @@ int clocksource_register(struct clocksource *cs)

mutex_lock(&clocksource_mutex);
clocksource_enqueue(cs);
- clocksource_select();
clocksource_enqueue_watchdog(cs);
+ clocksource_select();
mutex_unlock(&clocksource_mutex);
return 0;
}
--
1.7.9.3


\
 
 \ /
  Last update: 2012-03-13 01:31    [W:0.331 / U:1.672 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site