[PATCH 00/11] 2.6.34-stable: Fix for leapsecond deadlock & hrtimer/futex issue

[John Stultz]

Here is backport of the leapsecond fixes to 2.6.34-stable. These are less
straight forward, and should get closer review.

This patch set addresses two issues:

1) Deadlock leapsecond issue that a few reports described.

I spent some time over the weekend trying to find a way to reproduce
the hard-hang issue some folks were reporting after the leapsecond.
Initially I didn't think the 6b43ae8a619d17 leap-second hrimter livelock
patch needed to be backported since, I assumed it required the ntp_lock
split for it to be triggered, but looking again I found that the same
issue could occur prior to splitting out the ntp_lock. So I've backported
that fix (and its follow-on fixups) as well as created a test case
to reproduce the hard-hang deadlock.


2) Early hrtimer/futex expiration issue that was more widely observed

This is the load-spike issue that a number of folks saw that did not
hard hang most boxes (although some reports did show nmi-watchdogs
triggering due to sudden spinning in tight loops).

I've booted and tested this entire patchset on two boxes and run through a
number of leapsecond related stress tests. However, additional testing and
review would be appreciated. Especially as the backports get further away
from upstream.

The original commits backported in this set are:

Deadlock issue fixes:
---------------------
6b43ae8a619d17c4935c3320d2ef9e92bdeed05d    ntp: Fix leap-second hrtimer livelock
dd48d708ff3e917f6d6b6c2b696c3f18c019feed    ntp: Correct TAI offset during leap second
fad0c66c4bb836d57a5f125ecd38bed653ca863a    timekeeping: Fix CLOCK_MONOTONIC inconsistency during leapsecond

Helper change: (allows the following fixes to backport more easily):
--------------------------------------------------------------------
cc06268c6a87db156af2daed6e96a936b955cc82    time: Move common updates to a function

Hrtimer early-expiration issue fixes:
-------------------------------------
f55a6faa384304c89cfef162768e88374d3312cb    hrtimer: Provide clock_was_set_delayed()
4873fa070ae84a4115f0b3c9dfabc224f1bc7c51    timekeeping: Fix leapsecond triggered load spike issue
5b9fe759a678e05be4937ddf03d50e950207c1c0    timekeeping: Maintain ktime_t based offsets for hrtimers
196951e91262fccda81147d2bcf7fdab08668b40    hrtimers: Move lock held region in hrtimer_interrupt()
f6c06abfb3972ad4914cef57d8348fcb2932bc3b    timekeeping: Provide hrtimer update function
5baefd6d84163443215f4a99f6a20f054ef11236    hrtimer: Update hrtimer base offsets each hrtimer_interrupt
3e997130bd2e8c6f5aaa49d6e3161d4d29b43ab0    timekeeping: Add missing update call in timekeeping_resume()


I'll be sending the remaining 2.6.32, backport out soon.

Please let me know if you have any comments or feedback. 

thanks
-john


Cc: Prarit Bhargava <prarit@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Linux Kernel <linux-kernel@xxxxxxxxxxxxxxx>


John Stultz (5):
  2.6.34.x: ntp: Fix leap-second hrtimer livelock
  2.6.34.x: timekeeping: Fix CLOCK_MONOTONIC inconsistency during
    leapsecond
  2.6.34.x: hrtimer: Provide clock_was_set_delayed()
  2.6.34.x: timekeeping: Fix leapsecond triggered load spike issue
  2.6.34.x: hrtimer: Update hrtimer base offsets each hrtimer_interrupt

Richard Cochran (1):
  2.6.34.x: ntp: Correct TAI offset during leap second

Thomas Gleixner (5):
  2.6.34.x: time: Move common updates to a function
  2.6.34.x: timekeeping: Maintain ktime_t based offsets for hrtimers
  2.6.34.x: hrtimers: Move lock held region in hrtimer_interrupt()
  2.6.34.x: timekeeping: Provide hrtimer update function
  2.6.34.x: timekeeping: Add missing update call in
    timekeeping_resume()

 include/linux/hrtimer.h   |    9 +++-
 include/linux/timex.h     |    2 +-
 kernel/hrtimer.c          |   52 ++++++++++++-------
 kernel/time/ntp.c         |  124 +++++++++++++++------------------------------
 kernel/time/timekeeping.c |   93 ++++++++++++++++++++++++++++------
 5 files changed, 162 insertions(+), 118 deletions(-)

-- 
1.7.9.5

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