linux-stable.git/kernel/time/timekeeping.c, branch linux-2.6.34.y

timekeeping: add arch_offset hook to ktime_get functions

2013-01-16T21:44:58+00:00

commit d004e024058a0eaca097513ce62cbcf978913e0a upstream.

ktime_get and ktime_get_ts were calling timekeeping_get_ns()
but later they were not calling arch_gettimeoffset() so architectures
using this mechanism returned 0 ns when calling these functions.

This happened for example when running Busybox's ping which calls
syscall(__NR_clock_gettime, CLOCK_MONOTONIC, ts) which eventually
calls ktime_get. As a result the returned ping travel time was zero.

Signed-off-by: Hector Palacios 
Signed-off-by: John Stultz 
Signed-off-by: Paul Gortmaker

time: Move ktime_t overflow checking into timespec_valid_strict

2013-01-16T21:44:53+00:00

commit cee58483cf56e0ba355fdd97ff5e8925329aa936 upstream.

Andreas Bombe reported that the added ktime_t overflow checking added to
timespec_valid in commit 4e8b14526ca7 ("time: Improve sanity checking of
timekeeping inputs") was causing problems with X.org because it caused
timeouts larger then KTIME_T to be invalid.

Previously, these large timeouts would be clamped to KTIME_MAX and would
never expire, which is valid.

This patch splits the ktime_t overflow checking into a new
timespec_valid_strict function, and converts the timekeeping codes
internal checking to use this more strict function.

Reported-and-tested-by: Andreas Bombe 
Cc: Zhouping Liu 
Cc: Ingo Molnar 
Cc: Prarit Bhargava 
Cc: Thomas Gleixner 
Signed-off-by: John Stultz 
Signed-off-by: Linus Torvalds 
Cc: Linux Kernel 
Signed-off-by: John Stultz 
Signed-off-by: Paul Gortmaker

time: Avoid making adjustments if we haven't accumulated anything

2013-01-16T21:44:53+00:00

commit bf2ac312195155511a0f79325515cbb61929898a upstream.

If update_wall_time() is called and the current offset isn't large
enough to accumulate, avoid re-calling timekeeping_adjust which may
change the clock freq and can cause 1ns inconsistencies with
CLOCK_REALTIME_COARSE/CLOCK_MONOTONIC_COARSE.

Signed-off-by: John Stultz 
Cc: Prarit Bhargava 
Cc: Ingo Molnar 
Link: http://lkml.kernel.org/r/1345595449-34965-5-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner 
Cc: Linux Kernel 
Signed-off-by: John Stultz 
Signed-off-by: Paul Gortmaker

time: Improve sanity checking of timekeeping inputs

2013-01-16T21:44:53+00:00

commit 4e8b14526ca7fb046a81c94002c1c43b6fdf0e9b upstream.

Unexpected behavior could occur if the time is set to a value large
enough to overflow a 64bit ktime_t (which is something larger then the
year 2262).

Also unexpected behavior could occur if large negative offsets are
injected via adjtimex.

So this patch improves the sanity check timekeeping inputs by
improving the timespec_valid() check, and then makes better use of
timespec_valid() to make sure we don't set the time to an invalid
negative value or one that overflows ktime_t.

Note: This does not protect from setting the time close to overflowing
ktime_t and then letting natural accumulation cause the overflow.

Reported-by: CAI Qian 
Reported-by: Sasha Levin 
Signed-off-by: John Stultz 
Cc: Peter Zijlstra 
Cc: Prarit Bhargava 
Cc: Zhouping Liu 
Cc: Ingo Molnar 
Link: http://lkml.kernel.org/r/1344454580-17031-1-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner 
Cc: Linux Kernel 
Signed-off-by: John Stultz 
Signed-off-by: Paul Gortmaker

timekeeping: Add missing update call in timekeeping_resume()

2012-08-17T19:35:50+00:00

commit 3e997130bd2e8c6f5aaa49d6e3161d4d29b43ab0 upstream.

The leap second rework unearthed another issue of inconsistent data.

On timekeeping_resume() the timekeeper data is updated, but nothing
calls timekeeping_update(), so now the update code in the timer
interrupt sees stale values.

This has been the case before those changes, but then the timer
interrupt was using stale data as well so this went unnoticed for quite
some time.

Add the missing update call, so all the data is consistent everywhere.

Reported-by: Andreas Schwab 
Reported-and-tested-by: "Rafael J. Wysocki" 
Reported-and-tested-by: Martin Steigerwald 
Cc: LKML 
Cc: Linux PM list 
Cc: John Stultz 
Cc: Ingo Molnar 
Cc: Peter Zijlstra ,
Cc: Prarit Bhargava 
Signed-off-by: Thomas Gleixner 
Signed-off-by: John Stultz 
Signed-off-by: Linus Torvalds 
Cc: Prarit Bhargava 
Cc: Thomas Gleixner 
Cc: Linux Kernel 
Signed-off-by: John Stultz 
Signed-off-by: Paul Gortmaker

timekeeping: Provide hrtimer update function

2012-08-17T19:35:49+00:00

commit f6c06abfb3972ad4914cef57d8348fcb2932bc3b upstream.

To finally fix the infamous leap second issue and other race windows
caused by functions which change the offsets between the various time
bases (CLOCK_MONOTONIC, CLOCK_REALTIME and CLOCK_BOOTTIME) we need a
function which atomically gets the current monotonic time and updates
the offsets of CLOCK_REALTIME and CLOCK_BOOTTIME with minimalistic
overhead. The previous patch which provides ktime_t offsets allows us
to make this function almost as cheap as ktime_get() which is going to
be replaced in hrtimer_interrupt().

Signed-off-by: Thomas Gleixner 
Reviewed-by: Ingo Molnar 
Acked-by: Peter Zijlstra 
Acked-by: Prarit Bhargava 
Signed-off-by: John Stultz 
Link: http://lkml.kernel.org/r/1341960205-56738-7-git-send-email-johnstul@us.ibm.com
Signed-off-by: Thomas Gleixner 
Cc: Prarit Bhargava 
Cc: Thomas Gleixner 
Cc: Linux Kernel 
Signed-off-by: John Stultz 
Signed-off-by: Paul Gortmaker

timekeeping: Maintain ktime_t based offsets for hrtimers

2012-08-17T19:35:48+00:00

commit 5b9fe759a678e05be4937ddf03d50e950207c1c0 upstream.

We need to update the hrtimer clock offsets from the hrtimer interrupt
context. To avoid conversions from timespec to ktime_t maintain a
ktime_t based representation of those offsets in the timekeeper. This
puts the conversion overhead into the code which updates the
underlying offsets and provides fast accessible values in the hrtimer
interrupt.

Signed-off-by: Thomas Gleixner 
Signed-off-by: John Stultz 
Reviewed-by: Ingo Molnar 
Acked-by: Peter Zijlstra 
Acked-by: Prarit Bhargava 
Link: http://lkml.kernel.org/r/1341960205-56738-4-git-send-email-johnstul@us.ibm.com
Signed-off-by: Thomas Gleixner 
Cc: Prarit Bhargava 
Cc: Thomas Gleixner 
Cc: Linux Kernel 
Signed-off-by: John Stultz 
Signed-off-by: Paul Gortmaker

timekeeping: Fix leapsecond triggered load spike issue

2012-08-17T19:35:47+00:00

commit 4873fa070ae84a4115f0b3c9dfabc224f1bc7c51 upstream.

The timekeeping code misses an update of the hrtimer subsystem after a
leap second happened. Due to that timers based on CLOCK_REALTIME are
either expiring a second early or late depending on whether a leap
second has been inserted or deleted until an operation is initiated
which causes that update. Unless the update happens by some other
means this discrepancy between the timekeeping and the hrtimer data
stays forever and timers are expired either early or late.

The reported immediate workaround - $ data -s "`date`" - is causing a
call to clock_was_set() which updates the hrtimer data structures.
See: http://www.sheeri.com/content/mysql-and-leap-second-high-cpu-and-fix

Add the missing clock_was_set() call to update_wall_time() in case of
a leap second event. The actual update is deferred to softirq context
as the necessary smp function call cannot be invoked from hard
interrupt context.

Signed-off-by: John Stultz 
Reported-by: Jan Engelhardt 
Reviewed-by: Ingo Molnar 
Acked-by: Peter Zijlstra 
Acked-by: Prarit Bhargava 
Link: http://lkml.kernel.org/r/1341960205-56738-3-git-send-email-johnstul@us.ibm.com
Signed-off-by: Thomas Gleixner 
Cc: Prarit Bhargava 
Cc: Thomas Gleixner 
Cc: Linux Kernel 
Signed-off-by: John Stultz 
Signed-off-by: Paul Gortmaker

time: Move common updates to a function

2012-08-17T19:35:46+00:00

commit cc06268c6a87db156af2daed6e96a936b955cc82 upstream.

While not a bugfix itself, it allows following fixes to backport
in a more straightforward manner.

CC: Thomas Gleixner 
CC: Eric Dumazet 
CC: Richard Cochran 
Signed-off-by: Thomas Gleixner 
Cc: Prarit Bhargava 
Cc: Thomas Gleixner 
Cc: Linux Kernel 
Signed-off-by: John Stultz 
Signed-off-by: Paul Gortmaker

timekeeping: Fix CLOCK_MONOTONIC inconsistency during leapsecond

2012-08-17T19:35:46+00:00

commit fad0c66c4bb836d57a5f125ecd38bed653ca863a upstream.
which resolves a bug the previous commit.

Commit 6b43ae8a61 (ntp: Fix leap-second hrtimer livelock) broke the
leapsecond update of CLOCK_MONOTONIC. The missing leapsecond update to
wall_to_monotonic causes discontinuities in CLOCK_MONOTONIC.

Adjust wall_to_monotonic when NTP inserted a leapsecond.

Reported-by: Richard Cochran 
Signed-off-by: John Stultz 
Tested-by: Richard Cochran 
Link: http://lkml.kernel.org/r/1338400497-12420-1-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner 
Cc: Prarit Bhargava 
Cc: Thomas Gleixner 
Cc: Linux Kernel 
Signed-off-by: John Stultz 
Signed-off-by: Paul Gortmaker