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

tick: Cleanup NOHZ per cpu data on cpu down

2014-02-10T21:11:03+00:00

commit 4b0c0f294f60abcdd20994a8341a95c8ac5eeb96 upstream.

Prarit reported a crash on CPU offline/online. The reason is that on
CPU down the NOHZ related per cpu data of the dead cpu is not cleaned
up. If at cpu online an interrupt happens before the per cpu tick
device is registered the irq_enter() check potentially sees stale data
and dereferences a NULL pointer.

Cleanup the data after the cpu is dead.

Reported-by: Prarit Bhargava 
Cc: Mike Galbraith 
Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1305031451561.2886@ionos
Signed-off-by: Thomas Gleixner 
Signed-off-by: Paul Gortmaker

clockevents: Don't allow dummy broadcast timers

2014-02-10T21:11:03+00:00

commit a7dc19b8652c862d5b7c4d2339bd3c428bd29c4a upstream.

Currently tick_check_broadcast_device doesn't reject clock_event_devices
with CLOCK_EVT_FEAT_DUMMY, and may select them in preference to real
hardware if they have a higher rating value. In this situation, the
dummy timer is responsible for broadcasting to itself, and the core
clockevents code may attempt to call non-existent callbacks for
programming the dummy, eventually leading to a panic.

This patch makes tick_check_broadcast_device always reject dummy timers,
preventing this problem.

Signed-off-by: Mark Rutland 
Cc: linux-arm-kernel@lists.infradead.org
Cc: Jon Medhurst (Tixy) 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Paul Gortmaker

tick-broadcast: Stop active broadcast device when replacing it

2013-01-16T21:45:01+00:00

commit c1be84309c58b1e7c6d626e28fba41a22b364c3d upstream.

When a better rated broadcast device is installed, then the current
active device is not disabled, which results in two running broadcast
devices.

Signed-off-by: Thomas Gleixner 
Signed-off-by: Paul Gortmaker

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