linux-stable.git/kernel/time/clocksource.c, branch v3.4.112

clocksource: Fix abs() usage w/ 64bit values

2016-04-27T10:55:25+00:00

commit 67dfae0cd72fec5cd158b6e5fb1647b7dbe0834c upstream.

This patch fixes one cases where abs() was being used with 64-bit
nanosecond values, where the result may be capped at 32-bits.

This potentially could cause watchdog false negatives on 32-bit
systems, so this patch addresses the issue by using abs64().

Signed-off-by: John Stultz 
Cc: Prarit Bhargava 
Cc: Richard Cochran 
Cc: Ingo Molnar 
Link: http://lkml.kernel.org/r/1442279124-7309-2-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner 
[lizf: Backported to 3.4: adjust context]
Signed-off-by: Zefan Li

kernel-time: fix s/then/than/ spelling errors

2012-03-23T23:49:21+00:00

Use than for comparisons, like more than.

CC: John Stultz 
Signed-off-by: Jim Cromie 
Signed-off-by: John Stultz

Merge branch 'driver-core-next' into Linux 3.2

2012-01-06T19:42:52+00:00

This resolves the conflict in the arch/arm/mach-s3c64xx/s3c6400.c file,
and it fixes the build error in the arch/x86/kernel/microcode_core.c
file, that the merge did not catch.

The microcode_core.c patch was provided by Stephen Rothwell
 who was invaluable in the merge issues involved
with the large sysdev removal process in the driver-core tree.

Signed-off-by: Greg Kroah-Hartman

time/clocksource: Fix kernel-doc warnings

2011-12-19T10:41:40+00:00

Fix various KernelDoc build warnings.

Signed-off-by: Kusanagi Kouichi 
Cc: John Stultz 
Link: http://lkml.kernel.org/r/20111219091320.0D5AF6FC03D@msa105.auone-net.jp
Signed-off-by: Ingo Molnar

clocksource: convert sysdev_class to a regular subsystem

2011-12-14T23:28:51+00:00

After all sysdev classes are ported to regular driver core entities, the
sysdev implementation will be entirely removed from the kernel.

Cc: John Stultz 
Cc: Thomas Gleixner 
Signed-off-by: Kay Sievers 
Signed-off-by: Greg Kroah-Hartman

clocksource: Fix bug with max_deferment margin calculation

2011-12-01T23:50:00+00:00

In order to leave a margin of 12.5% we should >> 3 not >> 5.

CC: stable@kernel.org
Signed-off-by: Yang Honggang (Joseph) 
[jstultz: Modified commit subject]
Signed-off-by: John Stultz

clocksource: Avoid selecting mult values that might overflow when adjusted

2011-11-10T19:27:08+00:00

For some frequencies, the clocks_calc_mult_shift() function will
unfortunately select mult values very close to 0xffffffff.  This
has the potential to overflow when NTP adjusts the clock, adding
to the mult value.

This patch adds a clocksource.maxadj value, which provides
an approximation of an 11% adjustment(NTP limits adjustments to
500ppm and the tick adjustment is limited to 10%), which could
be made to the clocksource.mult value. This is then used to both
check that the current mult value won't overflow/underflow, as
well as warning us if the timekeeping_adjust() code pushes over
that 11% boundary.

v2: Fix max_adjustment calculation, and improve WARN_ONCE
messages.

v3: Don't warn before maxadj has actually been set

CC: Yong Zhang 
CC: David Daney 
CC: Thomas Gleixner 
CC: Chen Jie 
CC: zhangfx 
CC: stable@kernel.org
Reported-by: Chen Jie 
Reported-by: zhangfx 
Tested-by: Yong Zhang 
Signed-off-by: John Stultz

clocksource: Make watchdog reset lockless

2011-09-13T07:58:29+00:00

KGDB needs to trylock watchdog_lock when trying to reset the
clocksource watchdog after the system has been stopped to avoid a
potential deadlock. When the trylock fails TSC usually becomes
unstable.

We can be more clever by using an atomic counter and checking it in
the clocksource_watchdog callback. We restart the watchdog whenever
the counter is > 0 and only decrement the counter when we ran through
a full update cycle.

Signed-off-by: Thomas Gleixner 
Cc: John Stultz 
Acked-by: Jason Wessel 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1109121326280.2723@ionos
Signed-off-by: Thomas Gleixner

clocksource: Make watchdog robust vs. interruption

2011-06-16T17:30:53+00:00

The clocksource watchdog code is interruptible and it has been
observed that this can trigger false positives which disable the TSC.

The reason is that an interrupt storm or a long running interrupt
handler between the read of the watchdog source and the read of the
TSC brings the two far enough apart that the delta is larger than the
unstable treshold. Move both reads into a short interrupt disabled
region to avoid that.

Reported-and-tested-by: Vernon Mauery 
Signed-off-by: Thomas Gleixner 
Cc: stable@kernel.org

clockevents/source: Use u64 to make 32bit happy

2011-05-20T08:50:52+00:00

unsigned long is not 64bit on 32bit machine.

Signed-off-by: Thomas Gleixner