linux/kernel/time
John Stultz ec145babe7 time: Fix timeekeping_get_ns overflow on 32bit systems
Daniel Lezcano reported seeing multi-second stalls from
keyboard input on his T61 laptop when NOHZ and CPU_IDLE
were enabled on a 32bit kernel.

He bisected the problem down to commit
1e75fa8be9 ("time: Condense timekeeper.xtime into xtime_sec").

After reproducing this issue, I narrowed the problem down
to the fact that timekeeping_get_ns() returns a 64bit
nsec value that hasn't been accumulated. In some cases
this value was being then stored in timespec.tv_nsec
(which is a long).

On 32bit systems, with idle times larger then 4 seconds
(or less, depending on the value of xtime_nsec), the
returned nsec value would overflow 32bits. This limited
kept time from increasing, causing timers to not expire.

The fix is to make sure we don't directly store the
result of timekeeping_get_ns() into a tv_nsec field,
instead using a 64bit nsec value which can then be
added into the timespec via timespec_add_ns().

Reported-and-bisected-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Tested-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Acked-by: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Link: http://lkml.kernel.org/r/1347405963-35715-1-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-09-13 17:39:14 +02:00
..
alarmtimer.c alarmtimer: Provide accessor to alarmtimer rtc device 2012-04-20 14:56:36 -07:00
clockevents.c clockevents: Make clockevents_config() a global symbol 2012-05-25 01:44:51 +02:00
clocksource.c kernel-time: fix s/then/than/ spelling errors 2012-03-23 16:49:21 -07:00
jiffies.c time/jiffies: Rename ACTHZ to SHIFTED_HZ 2012-07-31 17:09:12 +02:00
Kconfig timers: Fixup the Kconfig consolidation fallout 2012-05-21 23:43:46 +02:00
Makefile timers: Introduce in-kernel alarm-timer interface 2011-04-26 14:01:44 -07:00
ntp.c time/jiffies: Rename ACTHZ to SHIFTED_HZ 2012-07-31 17:09:12 +02:00
posix-clock.c kernel: Fix files explicitly needing EXPORT_SYMBOL infrastructure 2011-10-31 19:30:05 -04:00
tick-broadcast.c tick: Fix the spurious broadcast timer ticks after resume 2012-04-19 21:27:50 +02:00
tick-common.c clockevents: Make minimum delay adjustments configurable 2011-09-08 11:10:56 +02:00
tick-internal.h clockevents: Make minimum delay adjustments configurable 2011-09-08 11:10:56 +02:00
tick-oneshot.c clockevents: Make minimum delay adjustments configurable 2011-09-08 11:10:56 +02:00
tick-sched.c Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-07-22 11:35:46 -07:00
timecompare.c time: Use ARRAY_SIZE macro in timecompare.c 2010-10-21 17:30:06 +02:00
timeconv.c time: add function to convert between calendar time and broken-down time for universal use 2009-09-24 07:20:56 -07:00
timekeeping.c time: Fix timeekeping_get_ns overflow on 32bit systems 2012-09-13 17:39:14 +02:00
timer_list.c nohz: Rename ts->idle_tick to ts->last_tick 2012-06-11 20:07:17 +02:00
timer_stats.c locking, timer_stats: Annotate table_lock as raw 2011-09-13 11:12:00 +02:00