<feed xmlns='http://www.w3.org/2005/Atom'>
<title>user/sven/linux.git/kernel/time, branch v4.14</title>
<subtitle>Linux Kernel
</subtitle>
<id>https://git.stealer.net/cgit.cgi/user/sven/linux.git/atom?h=v4.14</id>
<link rel='self' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/atom?h=v4.14'/>
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<updated>2017-11-02T10:10:55Z</updated>
<entry>
<title>License cleanup: add SPDX GPL-2.0 license identifier to files with no license</title>
<updated>2017-11-02T10:10:55Z</updated>
<author>
<name>Greg Kroah-Hartman</name>
<email>gregkh@linuxfoundation.org</email>
</author>
<published>2017-11-01T14:07:57Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=b24413180f5600bcb3bb70fbed5cf186b60864bd'/>
<id>urn:sha1:b24413180f5600bcb3bb70fbed5cf186b60864bd</id>
<content type='text'>
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier.  The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
 - file had no licensing information it it.
 - file was a */uapi/* one with no licensing information in it,
 - file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode &amp; Windriver) producing SPDX
tag:value files created by Philippe Ombredanne.  Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed.  Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
 - Files considered eligible had to be source code files.
 - Make and config files were included as candidates if they contained &gt;5
   lines of source
 - File already had some variant of a license header in it (even if &lt;5
   lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

 - when both scanners couldn't find any license traces, file was
   considered to have no license information in it, and the top level
   COPYING file license applied.

   For non */uapi/* files that summary was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0                                              11139

   and resulted in the first patch in this series.

   If that file was a */uapi/* path one, it was "GPL-2.0 WITH
   Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0 WITH Linux-syscall-note                        930

   and resulted in the second patch in this series.

 - if a file had some form of licensing information in it, and was one
   of the */uapi/* ones, it was denoted with the Linux-syscall-note if
   any GPL family license was found in the file or had no licensing in
   it (per prior point).  Results summary:

   SPDX license identifier                            # files
   ---------------------------------------------------|------
   GPL-2.0 WITH Linux-syscall-note                       270
   GPL-2.0+ WITH Linux-syscall-note                      169
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
   LGPL-2.1+ WITH Linux-syscall-note                      15
   GPL-1.0+ WITH Linux-syscall-note                       14
   ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
   LGPL-2.0+ WITH Linux-syscall-note                       4
   LGPL-2.1 WITH Linux-syscall-note                        3
   ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
   ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1

   and that resulted in the third patch in this series.

 - when the two scanners agreed on the detected license(s), that became
   the concluded license(s).

 - when there was disagreement between the two scanners (one detected a
   license but the other didn't, or they both detected different
   licenses) a manual inspection of the file occurred.

 - In most cases a manual inspection of the information in the file
   resulted in a clear resolution of the license that should apply (and
   which scanner probably needed to revisit its heuristics).

 - When it was not immediately clear, the license identifier was
   confirmed with lawyers working with the Linux Foundation.

 - If there was any question as to the appropriate license identifier,
   the file was flagged for further research and to be revisited later
   in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights.  The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
 - a full scancode scan run, collecting the matched texts, detected
   license ids and scores
 - reviewing anything where there was a license detected (about 500+
   files) to ensure that the applied SPDX license was correct
 - reviewing anything where there was no detection but the patch license
   was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
   SPDX license was correct

This produced a worksheet with 20 files needing minor correction.  This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg.  Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected.  This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.)  Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart &lt;kstewart@linuxfoundation.org&gt;
Reviewed-by: Philippe Ombredanne &lt;pombredanne@nexb.com&gt;
Reviewed-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>drivers/pps: aesthetic tweaks to PPS-related content</title>
<updated>2017-09-09T01:26:51Z</updated>
<author>
<name>Robert P. J. Day</name>
<email>rpjday@crashcourse.ca</email>
</author>
<published>2017-09-08T23:17:19Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=a2d818030135c293f878fbb772cf40e7a14c5acc'/>
<id>urn:sha1:a2d818030135c293f878fbb772cf40e7a14c5acc</id>
<content type='text'>
Collection of aesthetic adjustments to various PPS-related files,
directories and Documentation, some quite minor just for the sake of
consistency, including:

 * Updated example of pps device tree node (courtesy Rodolfo G.)
 * "PPS-API" -&gt; "PPS API"
 * "pps_source_info_s" -&gt; "pps_source_info"
 * "ktimer driver" -&gt; "pps-ktimer driver"
 * "ppstest /dev/pps0" -&gt; "ppstest /dev/pps1" to match example
 * Add missing PPS-related entries to MAINTAINERS file
 * Other trivialities

Link: http://lkml.kernel.org/r/alpine.LFD.2.20.1708261048220.8106@localhost.localdomain
Signed-off-by: Robert P. J. Day &lt;rpjday@crashcourse.ca&gt;
Acked-by: Rodolfo Giometti &lt;giometti@enneenne.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>Merge tag 'pm-4.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm</title>
<updated>2017-09-05T19:19:08Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2017-09-05T19:19:08Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=439644096c1a6afb9bd9953130f4444a856f76c5'/>
<id>urn:sha1:439644096c1a6afb9bd9953130f4444a856f76c5</id>
<content type='text'>
Pull power management updates from Rafael Wysocki:
 "This time (again) cpufreq gets the majority of changes which mostly
  are driver updates (including a major consolidation of intel_pstate),
  some schedutil governor modifications and core cleanups.

  There also are some changes in the system suspend area, mostly related
  to diagnostics and debug messages plus some renames of things related
  to suspend-to-idle. One major change here is that suspend-to-idle is
  now going to be preferred over S3 on systems where the ACPI tables
  indicate to do so and provide requsite support (the Low Power Idle S0
  _DSM in particular). The system sleep documentation and the tools
  related to it are updated too.

  The rest is a few cpuidle changes (nothing major), devfreq updates,
  generic power domains (genpd) framework updates and a few assorted
  modifications elsewhere.

  Specifics:

   - Drop the P-state selection algorithm based on a PID controller from
     intel_pstate and make it use the same P-state selection method
     (based on the CPU load) for all types of systems in the active mode
     (Rafael Wysocki, Srinivas Pandruvada).

   - Rework the cpufreq core and governors to make it possible to take
     cross-CPU utilization updates into account and modify the schedutil
     governor to actually do so (Viresh Kumar).

   - Clean up the handling of transition latency information in the
     cpufreq core and untangle it from the information on which drivers
     cannot do dynamic frequency switching (Viresh Kumar).

   - Add support for new SoCs (MT2701/MT7623 and MT7622) to the mediatek
     cpufreq driver and update its DT bindings (Sean Wang).

   - Modify the cpufreq dt-platdev driver to autimatically create
     cpufreq devices for the new (v2) Operating Performance Points (OPP)
     DT bindings and update its whitelist of supported systems (Viresh
     Kumar, Shubhrajyoti Datta, Marc Gonzalez, Khiem Nguyen, Finley
     Xiao).

   - Add support for Ux500 to the cpufreq-dt driver and drop the
     obsolete dbx500 cpufreq driver (Linus Walleij, Arnd Bergmann).

   - Add new SoC (R8A7795) support to the cpufreq rcar driver (Khiem
     Nguyen).

   - Fix and clean up assorted issues in the cpufreq drivers and core
     (Arvind Yadav, Christophe Jaillet, Colin Ian King, Gustavo Silva,
     Julia Lawall, Leonard Crestez, Rob Herring, Sudeep Holla).

   - Update the IO-wait boost handling in the schedutil governor to make
     it less aggressive (Joel Fernandes).

   - Rework system suspend diagnostics to make it print fewer messages
     to the kernel log by default, add a sysfs knob to allow more
     suspend-related messages to be printed and add Low Power S0 Idle
     constraints checks to the ACPI suspend-to-idle code (Rafael
     Wysocki, Srinivas Pandruvada).

   - Prefer suspend-to-idle over S3 on ACPI-based systems with the
     ACPI_FADT_LOW_POWER_S0 flag set and the Low Power Idle S0 _DSM
     interface present in the ACPI tables (Rafael Wysocki).

   - Update documentation related to system sleep and rename a number of
     items in the code to make it cleare that they are related to
     suspend-to-idle (Rafael Wysocki).

   - Export a variable allowing device drivers to check the target
     system sleep state from the core system suspend code (Florian
     Fainelli).

   - Clean up the cpuidle subsystem to handle the polling state on x86
     in a more straightforward way and to use %pOF instead of full_name
     (Rafael Wysocki, Rob Herring).

   - Update the devfreq framework to fix and clean up a few minor issues
     (Chanwoo Choi, Rob Herring).

   - Extend diagnostics in the generic power domains (genpd) framework
     and clean it up slightly (Thara Gopinath, Rob Herring).

   - Fix and clean up a couple of issues in the operating performance
     points (OPP) framework (Viresh Kumar, Waldemar Rymarkiewicz).

   - Add support for RV1108 to the rockchip-io Adaptive Voltage Scaling
     (AVS) driver (David Wu).

   - Fix the usage of notifiers in CPU power management on some
     platforms (Alex Shi).

   - Update the pm-graph system suspend/hibernation and boot profiling
     utility (Todd Brandt).

   - Make it possible to run the cpupower utility without CPU0 (Prarit
     Bhargava)"

* tag 'pm-4.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (87 commits)
  cpuidle: Make drivers initialize polling state
  cpuidle: Move polling state initialization code to separate file
  cpuidle: Eliminate the CPUIDLE_DRIVER_STATE_START symbol
  cpufreq: imx6q: Fix imx6sx low frequency support
  cpufreq: speedstep-lib: make several arrays static, makes code smaller
  PM: docs: Delete the obsolete states.txt document
  PM: docs: Describe high-level PM strategies and sleep states
  PM / devfreq: Fix memory leak when fail to register device
  PM / devfreq: Add dependency on PM_OPP
  PM / devfreq: Move private devfreq_update_stats() into devfreq
  PM / devfreq: Convert to using %pOF instead of full_name
  PM / AVS: rockchip-io: add io selectors and supplies for RV1108
  cpufreq: ti: Fix 'of_node_put' being called twice in error handling path
  cpufreq: dt-platdev: Drop few entries from whitelist
  cpufreq: dt-platdev: Automatically create cpufreq device with OPP v2
  ARM: ux500: don't select CPUFREQ_DT
  cpuidle: Convert to using %pOF instead of full_name
  cpufreq: Convert to using %pOF instead of full_name
  PM / Domains: Convert to using %pOF instead of full_name
  cpufreq: Cap the default transition delay value to 10 ms
  ...
</content>
</entry>
<entry>
<title>Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip</title>
<updated>2017-09-04T20:06:34Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2017-09-04T20:06:34Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=dd90cccffc20a15d8e4c3ac8813f4b6a6cd4766f'/>
<id>urn:sha1:dd90cccffc20a15d8e4c3ac8813f4b6a6cd4766f</id>
<content type='text'>
Pull timer fixes from Thomas Gleixner:
 "A rather small update for the time(r) subsystem:

   - A new clocksource driver IMX-TPM

   - Minor fixes to the alarmtimer facility

   - Device tree cleanups for Renesas drivers

   - A new kselftest and fixes for the timer related tests

   - Conversion of the clocksource drivers to use %pOF

   - Use the proper helpers to access rlimits in the posix-cpu-timer
     code"

* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  alarmtimer: Ensure RTC module is not unloaded
  clocksource: Convert to using %pOF instead of full_name
  clocksource/drivers/bcm2835: Remove message for a memory allocation failure
  devicetree: bindings: Remove deprecated properties
  devicetree: bindings: Remove unused 32-bit CMT bindings
  devicetree: bindings: Deprecate property, update example
  devicetree: bindings: r8a73a4 and R-Car Gen2 CMT bindings
  devicetree: bindings: R-Car Gen2 CMT0 and CMT1 bindings
  devicetree: bindings: Remove sh7372 CMT binding
  clocksource/drivers/imx-tpm: Add imx tpm timer support
  dt-bindings: timer: Add nxp tpm timer binding doc
  posix-cpu-timers: Use dedicated helper to access rlimit values
  alarmtimer: Fix unavailable wake-up source in sysfs
  timekeeping: Use proper timekeeper for debug code
  kselftests: timers: set-timer-lat: Add one-shot timer test cases
  kselftests: timers: set-timer-lat: Tweak reporting when timer fires early
  kselftests: timers: freq-step: Fix build warning
  kselftests: timers: freq-step: Define ADJ_SETOFFSET if device has older kernel headers
</content>
</entry>
<entry>
<title>Merge branch 'pm-sleep'</title>
<updated>2017-09-03T22:06:02Z</updated>
<author>
<name>Rafael J. Wysocki</name>
<email>rafael.j.wysocki@intel.com</email>
</author>
<published>2017-09-03T22:06:02Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=7b01463e51f6849d0787b24d06a62efcb243dd44'/>
<id>urn:sha1:7b01463e51f6849d0787b24d06a62efcb243dd44</id>
<content type='text'>
* pm-sleep:
  ACPI / PM: Check low power idle constraints for debug only
  PM / s2idle: Rename platform operations structure
  PM / s2idle: Rename -&gt;enter_freeze to -&gt;enter_s2idle
  PM / s2idle: Rename freeze_state enum and related items
  PM / s2idle: Rename PM_SUSPEND_FREEZE to PM_SUSPEND_TO_IDLE
  ACPI / PM: Prefer suspend-to-idle over S3 on some systems
  platform/x86: intel-hid: Wake up Dell Latitude 7275 from suspend-to-idle
  PM / suspend: Define pr_fmt() in suspend.c
  PM / suspend: Use mem_sleep_labels[] strings in messages
  PM / sleep: Put pm_test under CONFIG_PM_SLEEP_DEBUG
  PM / sleep: Check pm_wakeup_pending() in __device_suspend_noirq()
  PM / core: Add error argument to dpm_show_time()
  PM / core: Split dpm_suspend_noirq() and dpm_resume_noirq()
  PM / s2idle: Rearrange the main suspend-to-idle loop
  PM / timekeeping: Print debug messages when requested
  PM / sleep: Mark suspend/hibernation start and finish
  PM / sleep: Do not print debug messages by default
  PM / suspend: Export pm_suspend_target_state
</content>
</entry>
<entry>
<title>alarmtimer: Ensure RTC module is not unloaded</title>
<updated>2017-08-31T19:36:45Z</updated>
<author>
<name>Alexandre Belloni</name>
<email>alexandre.belloni@free-electrons.com</email>
</author>
<published>2017-08-20T22:01:46Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=51218298a25e6942957c5595f2abf130d47d5df9'/>
<id>urn:sha1:51218298a25e6942957c5595f2abf130d47d5df9</id>
<content type='text'>
When registering the rtc device to be used to handle alarm timers,
get_device is used to ensure the device doesn't go away but the module can
still be unloaded.

Call try_module_get to ensure the rtc driver will not go away.

Reported-and-tested-by: Michal Simek &lt;monstr@monstr.eu&gt;
Signed-off-by: Alexandre Belloni &lt;alexandre.belloni@free-electrons.com&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Acked-by: John Stultz &lt;john.stultz@linaro.org&gt;
Cc: Stephen Boyd &lt;sboyd@codeaurora.org&gt;
Link: http://lkml.kernel.org/r/20170820220146.30969-1-alexandre.belloni@free-electrons.com

</content>
</entry>
<entry>
<title>time: Fix ktime_get_raw() incorrect base accumulation</title>
<updated>2017-08-26T14:06:12Z</updated>
<author>
<name>John Stultz</name>
<email>john.stultz@linaro.org</email>
</author>
<published>2017-08-25T22:57:04Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=0bcdc0987cce9880436b70836c6a92bb8e744fd1'/>
<id>urn:sha1:0bcdc0987cce9880436b70836c6a92bb8e744fd1</id>
<content type='text'>
In comqit fc6eead7c1e2 ("time: Clean up CLOCK_MONOTONIC_RAW time
handling"), the following code got mistakenly added to the update of the
raw timekeeper:

 /* Update the monotonic raw base */
 seconds = tk-&gt;raw_sec;
 nsec = (u32)(tk-&gt;tkr_raw.xtime_nsec &gt;&gt; tk-&gt;tkr_raw.shift);
 tk-&gt;tkr_raw.base = ns_to_ktime(seconds * NSEC_PER_SEC + nsec);

Which adds the raw_sec value and the shifted down raw xtime_nsec to the
base value.

But the read function adds the shifted down tk-&gt;tkr_raw.xtime_nsec value
another time, The result of this is that ktime_get_raw() users (which are
all internal users) see the raw time move faster then it should (the rate
at which can vary with the current size of tkr_raw.xtime_nsec), which has
resulted in at least problems with graphics rendering performance.

The change tried to match the monotonic base update logic:

 seconds = (u64)(tk-&gt;xtime_sec + tk-&gt;wall_to_monotonic.tv_sec);
 nsec = (u32) tk-&gt;wall_to_monotonic.tv_nsec;
 tk-&gt;tkr_mono.base = ns_to_ktime(seconds * NSEC_PER_SEC + nsec);

Which adds the wall_to_monotonic.tv_nsec value, but not the
tk-&gt;tkr_mono.xtime_nsec value to the base.

To fix this, simplify the tkr_raw.base accumulation to only accumulate the
raw_sec portion, and do not include the tkr_raw.xtime_nsec portion, which
will be added at read time.

Fixes: fc6eead7c1e2 ("time: Clean up CLOCK_MONOTONIC_RAW time handling")
Reported-and-tested-by: Chris Wilson &lt;chris@chris-wilson.co.uk&gt;
Signed-off-by: John Stultz &lt;john.stultz@linaro.org&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Prarit Bhargava &lt;prarit@redhat.com&gt;
Cc: Kevin Brodsky &lt;kevin.brodsky@arm.com&gt;
Cc: Richard Cochran &lt;richardcochran@gmail.com&gt;
Cc: Stephen Boyd &lt;stephen.boyd@linaro.org&gt;
Cc: Will Deacon &lt;will.deacon@arm.com&gt;
Cc: Miroslav Lichvar &lt;mlichvar@redhat.com&gt;
Cc: Daniel Mentz &lt;danielmentz@google.com&gt;
Link: http://lkml.kernel.org/r/1503701824-1645-1-git-send-email-john.stultz@linaro.org

</content>
</entry>
<entry>
<title>timers: Fix excessive granularity of new timers after a nohz idle</title>
<updated>2017-08-24T09:40:18Z</updated>
<author>
<name>Nicholas Piggin</name>
<email>npiggin@gmail.com</email>
</author>
<published>2017-08-22T08:43:48Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=2fe59f507a65dbd734b990a11ebc7488f6f87a24'/>
<id>urn:sha1:2fe59f507a65dbd734b990a11ebc7488f6f87a24</id>
<content type='text'>
When a timer base is idle, it is forwarded when a new timer is added
to ensure that granularity does not become excessive. When not idle,
the timer tick is expected to increment the base.

However there are several problems:

- If an existing timer is modified, the base is forwarded only after
  the index is calculated.

- The base is not forwarded by add_timer_on.

- There is a window after a timer is restarted from a nohz idle, after
  it is marked not-idle and before the timer tick on this CPU, where a
  timer may be added but the ancient base does not get forwarded.

These result in excessive granularity (a 1 jiffy timeout can blow out
to 100s of jiffies), which cause the rcu lockup detector to trigger,
among other things.

Fix this by keeping track of whether the timer base has been idle
since it was last run or forwarded, and if so then forward it before
adding a new timer.

There is still a case where mod_timer optimises the case of a pending
timer mod with the same expiry time, where the timer can see excessive
granularity relative to the new, shorter interval. A comment is added,
but it's not changed because it is an important fastpath for
networking.

This has been tested and found to fix the RCU softlockup messages.

Testing was also done with tracing to measure requested versus
achieved wakeup latencies for all non-deferrable timers in an idle
system (with no lockup watchdogs running). Wakeup latency relative to
absolute latency is calculated (note this suffers from round-up skew
at low absolute times) and analysed:

             max     avg      std
upstream   506.0    1.20     4.68
patched      2.0    1.08     0.15

The bug was noticed due to the lockup detector Kconfig changes
dropping it out of people's .configs and resulting in larger base
clk skew When the lockup detectors are enabled, no CPU can go idle for
longer than 4 seconds, which limits the granularity errors.
Sub-optimal timer behaviour is observable on a smaller scale in that
case:

	     max     avg      std
upstream     9.0    1.05     0.19
patched      2.0    1.04     0.11

Fixes: Fixes: a683f390b93f ("timers: Forward the wheel clock whenever possible")
Signed-off-by: Nicholas Piggin &lt;npiggin@gmail.com&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Tested-by: Jonathan Cameron &lt;Jonathan.Cameron@huawei.com&gt;
Tested-by: David Miller &lt;davem@davemloft.net&gt;
Cc: dzickus@redhat.com
Cc: sfr@canb.auug.org.au
Cc: mpe@ellerman.id.au
Cc: Stephen Boyd &lt;sboyd@codeaurora.org&gt;
Cc: linuxarm@huawei.com
Cc: abdhalee@linux.vnet.ibm.com
Cc: John Stultz &lt;john.stultz@linaro.org&gt;
Cc: akpm@linux-foundation.org
Cc: paulmck@linux.vnet.ibm.com
Cc: torvalds@linux-foundation.org
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20170822084348.21436-1-npiggin@gmail.com

</content>
</entry>
<entry>
<title>Merge branch 'fortglx/4.14/time' of https://git.linaro.org/people/john.stultz/linux into timers/core</title>
<updated>2017-08-20T09:46:46Z</updated>
<author>
<name>Thomas Gleixner</name>
<email>tglx@linutronix.de</email>
</author>
<published>2017-08-20T09:46:46Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=4e2a809703e2b2300438a425b0a3f2013b55fcc6'/>
<id>urn:sha1:4e2a809703e2b2300438a425b0a3f2013b55fcc6</id>
<content type='text'>
Pull timekeepig updates from John Stultz

 - kselftest improvements

 - Use the proper timekeeper in the debug code

 - Prevent accessing an unavailable wakeup source in the alarmtimer sysfs
   interface.
</content>
</entry>
<entry>
<title>posix-cpu-timers: Use dedicated helper to access rlimit values</title>
<updated>2017-08-18T10:44:42Z</updated>
<author>
<name>Krzysztof Opasiak</name>
<email>k.opasiak@samsung.com</email>
</author>
<published>2017-07-05T17:25:48Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=3cf294962df8fcde710eb5e762e0929e2ba49947'/>
<id>urn:sha1:3cf294962df8fcde710eb5e762e0929e2ba49947</id>
<content type='text'>
Use rlimit() and rlimit_max() helper instead of manually writing
whole chain from task to rlimit value

Signed-off-by: Krzysztof Opasiak &lt;k.opasiak@samsung.com&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Link: http://lkml.kernel.org/r/20170705172548.7911-1-k.opasiak@samsung.com

</content>
</entry>
</feed>
