clocksource: Make negative motion detection more robust

Guenter reported boot stalls on a emulated ARM 32-bit platform, which has a
24-bit wide clocksource.

It turns out that the calculated maximal

clocksource: Make negative motion detection more robust

Guenter reported boot stalls on a emulated ARM 32-bit platform, which has a
24-bit wide clocksource.

It turns out that the calculated maximal idle time, which limits idle
sleeps to prevent clocksource wrap arounds, is close to the point where the
negative motion detection triggers.

max_idle_ns: 597268854 ns
negative motion tripping point: 671088640 ns

If the idle wakeup is delayed beyond that point, the clocksource
advances far enough to trigger the negative motion detection. This
prevents the clock to advance and in the worst case the system stalls
completely if the consecutive sleeps based on the stale clock are
delayed as well.

Cure this by calculating a more robust cut-off value for negative motion,
which covers 87.5% of the actual clocksource counter width. Compare the
delta against this value to catch negative motion. This is specifically for
clock sources with a small counter width as their wrap around time is close
to the half counter width. For clock sources with wide counters this is not
a problem because the maximum idle time is far from the half counter width
due to the math overflow protection constraints.

For the case at hand this results in a tripping point of 1174405120ns.

Note, that this cannot prevent issues when the delay exceeds the 87.5%
margin, but that's not different from the previous unchecked version which
allowed arbitrary time jumps.

Systems with small counter width are prone to invalid results, but this
problem is unlikely to be seen on real hardware. If such a system
completely stalls for more than half a second, then there are other more
urgent problems than the counter wrapping around.

Fixes: c163e40af9b2 ("timekeeping: Always check for negative motion")
Reported-by: Guenter Roeck <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Tested-by: Guenter Roeck <[email protected]>
Link: https://lore.kernel.org/all/8734j5ul4x.ffs@tglx
Closes: https://lore.kernel.org/all/[email protected]

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clocksource: Remove unused clocksource_change_rating

clocksource_change_rating() has been unused since 2017's commit
63ed4e0c67df ("Drivers: hv: vmbus: Consolidate all Hyper-V specific clocksource c

clocksource: Remove unused clocksource_change_rating

clocksource_change_rating() has been unused since 2017's commit
63ed4e0c67df ("Drivers: hv: vmbus: Consolidate all Hyper-V specific clocksource code")

Remove it.

__clocksource_change_rating now only has one use which is ifdef'd.
Move it into the ifdef'd section.

Signed-off-by: Dr. David Alan Gilbert <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/all/[email protected]

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timekeeping: Provide infrastructure for converting to/from a base clock

Hardware time stamps like provided by PTP clock implementations are based
on a clock which feeds both the PCIe device and the

timekeeping: Provide infrastructure for converting to/from a base clock

Hardware time stamps like provided by PTP clock implementations are based
on a clock which feeds both the PCIe device and the system clock. For
further processing the underlying hardwarre clock timestamp must be
converted to the system clock.

Right now this requires drivers to invoke an architecture specific
conversion function, e.g. to convert the ART (Always Running Timer)
timestamp to a TSC timestamp.

As the system clock is aware of the underlying base clock, this can be
moved to the core code by providing a base clock property for the system
clock which contains the conversion factors and assigning a clocksource ID
to the base clock.

Add the required data structures and the conversion infrastructure in the
core code to prepare for converting X86 and the related PTP drivers over.

[ tglx: Added a missing READ_ONCE(). Massaged change log ]

Co-developed-by: Thomas Gleixner <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Co-developed-by: Christopher S. Hall <[email protected]>
Signed-off-by: Christopher S. Hall <[email protected]>
Signed-off-by: Lakshmi Sowjanya D <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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clocksource: Scale the watchdog read retries automatically

On a 8-socket server the TSC is wrongly marked as 'unstable' and disabled
during boot time on about one out of 120 boot attempts:

cloc

clocksource: Scale the watchdog read retries automatically

On a 8-socket server the TSC is wrongly marked as 'unstable' and disabled
during boot time on about one out of 120 boot attempts:

clocksource: timekeeping watchdog on CPU227: wd-tsc-wd excessive read-back delay of 153560ns vs. limit of 125000ns,
wd-wd read-back delay only 11440ns, attempt 3, marking tsc unstable
tsc: Marking TSC unstable due to clocksource watchdog
TSC found unstable after boot, most likely due to broken BIOS. Use 'tsc=unstable'.
sched_clock: Marking unstable (119294969739, 159204297)<-(125446229205, -5992055152)
clocksource: Checking clocksource tsc synchronization from CPU 319 to CPUs 0,99,136,180,210,542,601,896.
clocksource: Switched to clocksource hpet

The reason is that for platform with a large number of CPUs, there are
sporadic big or huge read latencies while reading the watchog/clocksource
during boot or when system is under stress work load, and the frequency and
maximum value of the latency goes up with the number of online CPUs.

The cCurrent code already has logic to detect and filter such high latency
case by reading the watchdog twice and checking the two deltas. Due to the
randomness of the latency, there is a low probabilty that the first delta
(latency) is big, but the second delta is small and looks valid. The
watchdog code retries the readouts by default twice, which is not
necessarily sufficient for systems with a large number of CPUs.

There is a command line parameter 'max_cswd_read_retries' which allows to
increase the number of retries, but that's not user friendly as it needs to
be tweaked per system. As the number of required retries is proportional to
the number of online CPUs, this parameter can be calculated at runtime.

Scale and enlarge the number of retries according to the number of online
CPUs and remove the command line parameter completely.

[ tglx: Massaged change log and comments ]

Signed-off-by: Feng Tang <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Tested-by: Jin Wang <[email protected]>
Tested-by: Paul E. McKenney <[email protected]>
Reviewed-by: Waiman Long <[email protected]>
Reviewed-by: Paul E. McKenney <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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clocksource: Provide kernel module to test clocksource watchdog

When the clocksource watchdog marks a clock as unstable, this might
be due to that clock being unstable or it might be due to delays t

clocksource: Provide kernel module to test clocksource watchdog

When the clocksource watchdog marks a clock as unstable, this might
be due to that clock being unstable or it might be due to delays that
happen to occur between the reads of the two clocks. It would be good
to have a way of testing the clocksource watchdog's ability to
distinguish between these two causes of clock skew and instability.

Therefore, provide a new clocksource-wdtest module selected by a new
TEST_CLOCKSOURCE_WATCHDOG Kconfig option. This module has a single module
parameter named "holdoff" that provides the number of seconds of delay
before testing should start, which defaults to zero when built as a module
and to 10 seconds when built directly into the kernel. Very large systems
that boot slowly may need to increase the value of this module parameter.

This module uses hand-crafted clocksource structures to do its testing,
thus avoiding messing up timing for the rest of the kernel and for user
applications. This module first verifies that the ->uncertainty_margin
field of the clocksource structures are set sanely. It then tests the
delay-detection capability of the clocksource watchdog, increasing the
number of consecutive delays injected, first provoking console messages
complaining about the delays and finally forcing a clock-skew event.
Unexpected test results cause at least one WARN_ON_ONCE() console splat.
If there are no splats, the test has passed. Finally, it fuzzes the
value returned from a clocksource to test the clocksource watchdog's
ability to detect time skew.

This module checks the state of its clocksource after each test, and
uses WARN_ON_ONCE() to emit a console splat if there are any failures.
This should enable all types of test frameworks to detect any such
failures.

This facility is intended for diagnostic use only, and should be avoided
on production systems.

Reported-by: Chris Mason <[email protected]>
Suggested-by: Thomas Gleixner <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Tested-by: Feng Tang <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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clocksource: Reduce clocksource-skew threshold

Currently, WATCHDOG_THRESHOLD is set to detect a 62.5-millisecond skew in
a 500-millisecond WATCHDOG_INTERVAL. This requires that clocks be skewed
by

clocksource: Reduce clocksource-skew threshold

Currently, WATCHDOG_THRESHOLD is set to detect a 62.5-millisecond skew in
a 500-millisecond WATCHDOG_INTERVAL. This requires that clocks be skewed
by more than 12.5% in order to be marked unstable. Except that a clock
that is skewed by that much is probably destroying unsuspecting software
right and left. And given that there are now checks for false-positive
skews due to delays between reading the two clocks, it should be possible
to greatly decrease WATCHDOG_THRESHOLD, at least for fine-grained clocks
such as TSC.

Therefore, add a new uncertainty_margin field to the clocksource structure
that contains the maximum uncertainty in nanoseconds for the corresponding
clock. This field may be initialized manually, as it is for
clocksource_tsc_early and clocksource_jiffies, which is copied to
refined_jiffies. If the field is not initialized manually, it will be
computed at clock-registry time as the period of the clock in question
based on the scale and freq parameters to __clocksource_update_freq_scale()
function. If either of those two parameters are zero, the
tens-of-milliseconds WATCHDOG_THRESHOLD is used as a cowardly alternative
to dividing by zero. No matter how the uncertainty_margin field is
calculated, it is bounded below by twice WATCHDOG_MAX_SKEW, that is, by 100
microseconds.

Note that manually initialized uncertainty_margin fields are not adjusted,
but there is a WARN_ON_ONCE() that triggers if any such field is less than
twice WATCHDOG_MAX_SKEW. This WARN_ON_ONCE() is intended to discourage
production use of the one-nanosecond uncertainty_margin values that are
used to test the clock-skew code itself.

The actual clock-skew check uses the sum of the uncertainty_margin fields
of the two clocksource structures being compared. Integer overflow is
avoided because the largest computed value of the uncertainty_margin
fields is one billion (10^9), and double that value fits into an
unsigned int. However, if someone manually specifies (say) UINT_MAX,
they will get what they deserve.

Note that the refined_jiffies uncertainty_margin field is initialized to
TICK_NSEC, which means that skew checks involving this clocksource will
be sufficently forgiving. In a similar vein, the clocksource_tsc_early
uncertainty_margin field is initialized to 32*NSEC_PER_MSEC, which
replicates the current behavior and allows custom setting if needed
in order to address the rare skews detected for this clocksource in
current mainline.

Suggested-by: Thomas Gleixner <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Acked-by: Feng Tang <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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clocksource: Check per-CPU clock synchronization when marked unstable

Some sorts of per-CPU clock sources have a history of going out of
synchronization with each other. However, this problem has p

clocksource: Check per-CPU clock synchronization when marked unstable

Some sorts of per-CPU clock sources have a history of going out of
synchronization with each other. However, this problem has purportedy been
solved in the past ten years. Except that it is all too possible that the
problem has instead simply been made less likely, which might mean that
some of the occasional "Marking clocksource 'tsc' as unstable" messages
might be due to desynchronization. How would anyone know?

Therefore apply CPU-to-CPU synchronization checking to newly unstable
clocksource that are marked with the new CLOCK_SOURCE_VERIFY_PERCPU flag.
Lists of desynchronized CPUs are printed, with the caveat that if it
is the reporting CPU that is itself desynchronized, it will appear that
all the other clocks are wrong. Just like in real life.

Reported-by: Chris Mason <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Acked-by: Feng Tang <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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time: Add mechanism to recognize clocksource in time_get_snapshot

System time snapshots are not conveying information about the current
clocksource which was used, but callers like the PTP KVM guest

time: Add mechanism to recognize clocksource in time_get_snapshot

System time snapshots are not conveying information about the current
clocksource which was used, but callers like the PTP KVM guest
implementation have the requirement to evaluate the clocksource type to
select the appropriate mechanism.

Introduce a clocksource id field in struct clocksource which is by default
set to CSID_GENERIC (0). Clocksource implementations can set that field to
a value which allows to identify the clocksource.

Store the clocksource id of the current clocksource in the
system_time_snapshot so callers can evaluate which clocksource was used to
take the snapshot and act accordingly.

Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Jianyong Wu <[email protected]>
Signed-off-by: Marc Zyngier <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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timekeeping, clocksource: Fix various typos in comments

Fix ~56 single-word typos in timekeeping & clocksource code comments.

Signed-off-by: Ingo Molnar <[email protected]>
Cc: Thomas Gleixner <tglx

timekeeping, clocksource: Fix various typos in comments

Fix ~56 single-word typos in timekeeping & clocksource code comments.

Signed-off-by: Ingo Molnar <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: John Stultz <[email protected]>
Cc: Stephen Boyd <[email protected]>
Cc: Daniel Lezcano <[email protected]>
Cc: [email protected]

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linux/clocksource.h: Extract common header for vDSO

The vDSO library should only include the necessary headers required for
a userspace library (UAPI and a minimal set of kernel headers). To make
th

linux/clocksource.h: Extract common header for vDSO

The vDSO library should only include the necessary headers required for
a userspace library (UAPI and a minimal set of kernel headers). To make
this possible it is necessary to isolate from the kernel headers the
common parts that are strictly necessary to build the library.

Split clocksource.h into linux and common headers to make the latter
suitable for inclusion in the vDSO library.

Signed-off-by: Vincenzo Frascino <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

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lib/vdso: Move VCLOCK_TIMENS to vdso_clock_modes

Move the time namespace indicator clock mode to the other ones for
consistency sake.

Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by

lib/vdso: Move VCLOCK_TIMENS to vdso_clock_modes

Move the time namespace indicator clock mode to the other ones for
consistency sake.

Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Vincenzo Frascino <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

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lib/vdso: Cleanup clock mode storage leftovers

Now that all architectures are converted to use the generic storage the
helpers and conditionals can be removed.

Signed-off-by: Thomas Gleixner <tglx@

lib/vdso: Cleanup clock mode storage leftovers

Now that all architectures are converted to use the generic storage the
helpers and conditionals can be removed.

Signed-off-by: Thomas Gleixner <[email protected]>
Tested-by: Vincenzo Frascino <[email protected]>
Reviewed-by: Vincenzo Frascino <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

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clocksource: Add common vdso clock mode storage

All architectures which use the generic VDSO code have their own storage
for the VDSO clock mode. That's pointless and just requires duplicate code.

clocksource: Add common vdso clock mode storage

All architectures which use the generic VDSO code have their own storage
for the VDSO clock mode. That's pointless and just requires duplicate code.

Provide generic storage for it. The new Kconfig symbol is intermediate and
will be removed once all architectures are converted over.

Signed-off-by: Thomas Gleixner <[email protected]>
Tested-by: Vincenzo Frascino <[email protected]>
Reviewed-by: Vincenzo Frascino <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

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clocksource: Cleanup struct clocksource and documentation

Reformat the struct definition, add missing member documentation.
No functional change.

Signed-off-by: Thomas Gleixner <[email protected]>

clocksource: Cleanup struct clocksource and documentation

Reformat the struct definition, add missing member documentation.
No functional change.

Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Vincenzo Frascino <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

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clocksource: Provide clocksource_arch_init()

Architectures have extra archdata in the clocksource, e.g. for VDSO
support. There are no sanity checks or general initializations for this
available. Ad

clocksource: Provide clocksource_arch_init()

Architectures have extra archdata in the clocksource, e.g. for VDSO
support. There are no sanity checks or general initializations for this
available. Add support for that.

Signed-off-by: Thomas Gleixner <[email protected]>
Acked-by: Andy Lutomirski <[email protected]>
Acked-by: John Stultz <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Matt Rickard <[email protected]>
Cc: Stephen Boyd <[email protected]>
Cc: Florian Weimer <[email protected]>
Cc: "K. Y. Srinivasan" <[email protected]>
Cc: Vitaly Kuznetsov <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: Paolo Bonzini <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Juergen Gross <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

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clocksource: Remove obsolete CLOCKSOURCE_OF_DECLARE

The macro CLOCKSOURCE_OF_DECLARE was renamed more TIMER_OF_DECLARE, and we
kept an alias CLOCKSOURCE_OF_DECLARE in order to smooth the transition

clocksource: Remove obsolete CLOCKSOURCE_OF_DECLARE

The macro CLOCKSOURCE_OF_DECLARE was renamed more TIMER_OF_DECLARE, and we
kept an alias CLOCKSOURCE_OF_DECLARE in order to smooth the transition for
drivers.

This change was done 1.5 year ago, we can reasonably remove this backward
compatible macro as it is no longer used anywhere.

Signed-off-by: Daniel Lezcano <[email protected]>

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time: Introduce one suspend clocksource to compensate the suspend time

On some hardware with multiple clocksources, we have coarse grained
clocksources that support the CLOCK_SOURCE_SUSPEND_NONSTOP

time: Introduce one suspend clocksource to compensate the suspend time

On some hardware with multiple clocksources, we have coarse grained
clocksources that support the CLOCK_SOURCE_SUSPEND_NONSTOP flag, but
which are less than ideal for timekeeping whereas other clocksources
can be better candidates but halt on suspend.

Currently, the timekeeping core only supports timing suspend using
CLOCK_SOURCE_SUSPEND_NONSTOP clocksources if that clocksource is the
current clocksource for timekeeping.

As a result, some architectures try to implement read_persistent_clock64()
using those non-stop clocksources, but isn't really ideal, which will
introduce more duplicate code. To fix this, provide logic to allow a
registered SUSPEND_NONSTOP clocksource, which isn't the current
clocksource, to be used to calculate the suspend time.

Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Miroslav Lichvar <[email protected]>
Cc: Richard Cochran <[email protected]>
Cc: Prarit Bhargava <[email protected]>
Cc: Stephen Boyd <[email protected]>
Cc: Daniel Lezcano <[email protected]>
Reviewed-by: Thomas Gleixner <[email protected]>
Reviewed-by: Daniel Lezcano <[email protected]>
Suggested-by: Thomas Gleixner <[email protected]>
Signed-off-by: Baolin Wang <[email protected]>
[jstultz: minor tweaks to merge with previous resume changes]
Signed-off-by: John Stultz <[email protected]>

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License cleanup: add SPDX GPL-2.0 license identifier to files with no license

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

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 & 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 >5
lines of source
- File already had some variant of a license header in it (even if <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 <[email protected]>
Reviewed-by: Philippe Ombredanne <[email protected]>
Reviewed-by: Thomas Gleixner <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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clocksource/drivers: Add an alias macro CLOCKSOURCE_OF_DECLARE

The macro CLOCKSOURCE_OF_DECLARE has been rename to TIMER_OF_DECLARE.

In order to prevent conflicts for the next merge window, a tempo

clocksource/drivers: Add an alias macro CLOCKSOURCE_OF_DECLARE

The macro CLOCKSOURCE_OF_DECLARE has been rename to TIMER_OF_DECLARE.

In order to prevent conflicts for the next merge window, a temporary
alias has been added which will be removed later.

Cc: Arnd Bergman <[email protected]>
Signed-off-by: Daniel Lezcano <[email protected]>

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clocksource/drivers: Rename CLKSRC_OF to TIMER_OF

The config option name is now renamed to 'TIMER_OF' for consistency with
the CLOCKSOURCE_OF_DECLARE => TIMER_OF_DECLARE change.

Signed-off-by: Dani

clocksource/drivers: Rename CLKSRC_OF to TIMER_OF

The config option name is now renamed to 'TIMER_OF' for consistency with
the CLOCKSOURCE_OF_DECLARE => TIMER_OF_DECLARE change.

Signed-off-by: Daniel Lezcano <[email protected]>
Reviewed-by: Linus Walleij <[email protected]>

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clocksource/drivers: Rename clksrc table to timer

The table name is now renamed to 'timer' for consistency with
the CLOCKSOURCE_OF_DECLARE => TIMER_OF_DECLARE change.

Signed-off-by: Daniel Lezcano

clocksource/drivers: Rename clksrc table to timer

The table name is now renamed to 'timer' for consistency with
the CLOCKSOURCE_OF_DECLARE => TIMER_OF_DECLARE change.

Signed-off-by: Daniel Lezcano <[email protected]>
Reviewed-by: Linus Walleij <[email protected]>

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clocksource/drivers: Rename CLOCKSOURCE_ACPI_DECLARE to TIMER_ACPI_DECLARE

The macro name is now renamed to 'TIMER_ACPI_DECLARE' for consistency
with the CLOCKSOURCE_OF_DECLARE => TIMER_OF_DECLARE c

clocksource/drivers: Rename CLOCKSOURCE_ACPI_DECLARE to TIMER_ACPI_DECLARE

The macro name is now renamed to 'TIMER_ACPI_DECLARE' for consistency
with the CLOCKSOURCE_OF_DECLARE => TIMER_OF_DECLARE change.

Signed-off-by: Daniel Lezcano <[email protected]>
Reviewed-by: Linus Walleij <[email protected]>

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clocksource/drivers: Rename clocksource_probe to timer_probe

The function name is now renamed to 'timer_probe' for consistency with
the CLOCKSOURCE_OF_DECLARE => TIMER_OF_DECLARE change.

Signed-off

clocksource/drivers: Rename clocksource_probe to timer_probe

The function name is now renamed to 'timer_probe' for consistency with
the CLOCKSOURCE_OF_DECLARE => TIMER_OF_DECLARE change.

Signed-off-by: Daniel Lezcano <[email protected]>
Acked-by: Viresh Kumar <[email protected]>
Acked-by: Heiko Stuebner <[email protected]>
Reviewed-by: Linus Walleij <[email protected]>

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clocksource/drivers: Rename CLOCKSOURCE_OF_DECLARE to TIMER_OF_DECLARE

The CLOCKSOURCE_OF_DECLARE macro is used widely for the timers to declare the
clocksource at early stage. However, this macro i

clocksource/drivers: Rename CLOCKSOURCE_OF_DECLARE to TIMER_OF_DECLARE

The CLOCKSOURCE_OF_DECLARE macro is used widely for the timers to declare the
clocksource at early stage. However, this macro is also used to initialize
the clockevent if any, or the clockevent only.

It was originally suggested to declare another macro to initialize a
clockevent, so in order to separate the two entities even they belong to the
same IP. This was not accepted because of the impact on the DT where splitting
a clocksource/clockevent definition does not make sense as it is a Linux
concept not a hardware description.

On the other side, the clocksource has not interrupt declared while the
clockevent has, so it is easy from the driver to know if the description is
for a clockevent or a clocksource, IOW it could be implemented at the driver
level.

So instead of dealing with a named clocksource macro, let's use a more generic
one: TIMER_OF_DECLARE.

The patch has not functional changes.

Signed-off-by: Daniel Lezcano <[email protected]>
Acked-by: Heiko Stuebner <[email protected]>
Acked-by: Neil Armstrong <[email protected]>
Acked-by: Arnd Bergmann <[email protected]>
Acked-by: Matthias Brugger <[email protected]>
Reviewed-by: Linus Walleij <[email protected]>

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x86/tsc, sched/clock, clocksource: Use clocksource watchdog to provide stable sync points

Currently we keep sched_clock_tick() active for stable TSC in order to
keep the per-CPU state semi up-to-dat

x86/tsc, sched/clock, clocksource: Use clocksource watchdog to provide stable sync points

Currently we keep sched_clock_tick() active for stable TSC in order to
keep the per-CPU state semi up-to-date. The (obvious) problem is that
by the time we detect TSC is borked, our per-CPU state is also borked.

So hook into the clocksource watchdog and call a method after we've
found it to still be stable.

There's the obvious race where the TSC goes wonky between finding it
stable and us running the callback, but closing that is too much work
and not really worth it, since we're already detecting TSC wobbles
after the fact, so we cannot, per definition, fully avoid funny clock
values.

And since the watchdog runs less often than the tick, this is also an
optimization.

Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Signed-off-by: Ingo Molnar <[email protected]>

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