[PATCH 00/12] Increased clocksource validation and cleanups (v3)

[John Stultz]

So Ingo asked me to resend this series, which is the result of
earlier discussions with Linus and his suggestions around
improvements to clocksource validation in the hope we can more
easily catch bad hardware.

There's also a few cleanups Linus suggested as well as a few I've been
meaning to get to for awhile.

I tried in address all the feedback that had been given, adding
the checks behind CONFIG_DEBUG_TIMEKEEPING.  I also sorted out a
sane way to print rate-limited warnings if we see cycle deltas that
are too large, or if they look like small underflows.

I'd like to get this queued into -tip soon so it can get as much
testing in -next as possible.

If there are any objections or feedback, I'd love to hear it!

New in v3:
* Its been awhile since v2, and I don't recall any substantial changes,
  but I did change a function macro into a static inline per PeterZ's
  request.

thanks
-john

The patches are also available via a git pull:

The following changes since commit c517d838eb7d07bbe9507871fab3931deccff539:

  Linux 4.0-rc1 (2015-02-22 18:21:14 -0800)

are available in the git repository at:

  https://git.linaro.org/people/john.stultz/linux.git fortglx/4.1/time

for you to fetch changes up to 904d6befdcab1b9947c14dd517977782216daafa:

  clocksource: Add some debug info about clocksources being registered
(2015-02-25 20:58:30 -0800)


Cc: Dave Jones <davej@xxxxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Richard Cochran <richardcochran@xxxxxxxxx>
Cc: Prarit Bhargava <prarit@xxxxxxxxxx>
Cc: Stephen Boyd <sboyd@xxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>

John Stultz (12):
  clocksource: Simplify clocks_calc_max_nsecs logic
  clocksource: Simplify logic around clocksource wrapping saftey margins
  clocksource: Remove clocksource_max_deferment()
  clocksource: Add max_cycles to clocksource structure
  time: Add debugging checks to warn if we see delays
  time: Add infrastructure to cap clocksource reads to the max_cycles
    value
  time: Try to catch clocksource delta underflows
  time: Add warnings when overflows or underflows are observed
  clocksource: Improve clocksource watchdog reporting
  clocksource: Mostly kill clocksource_register()
  sparc: Convert to using clocksource_register_hz()
  clocksource: Add some debug info about clocksources being registered

 arch/s390/kernel/time.c     |   2 +-
 arch/sparc/kernel/time_32.c |   6 +-
 include/linux/clocksource.h |  16 ++++-
 kernel/time/clocksource.c   | 164 +++++++++++++++++++-------------------------
 kernel/time/jiffies.c       |   5 +-
 kernel/time/sched_clock.c   |   6 +-
 kernel/time/timekeeping.c   | 116 +++++++++++++++++++++++++++----
 lib/Kconfig.debug           |  12 ++++
 8 files changed, 208 insertions(+), 119 deletions(-)

-- 
1.9.1

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