tick: Move broadcast cancellation up to CPUHP_AP_TICK_DYING

The broadcast shutdown code is executed through a random explicit call
within stop machine from the outgoing CPU.

However the tick broadcast is a midware between the tick callback and
the clocksource, therefore it makes more sense to shut it down after the
tick callback and before the clocksource drivers.

Move it instead to the common tick shutdown CPU hotplug state where
related operations can be ordered from highest to lowest level.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240225225508.11587-10-frederic@kernel.org

timers: Implement the hierarchical pull model

Placing timers at enqueue time on a target CPU based on dubious heuristics
does not make any sense:

1) Most timer wheel timers are canceled or rearmed before they expire.

2) The heuristics to predict which CPU will be busy when the timer expires
are wrong by definition.

So placing the timers at enqueue wastes precious cycles.

The proper solution to this problem is to always queue the timers on the
local CPU and allow the non pinned timers to be pulled onto a busy CPU at
expiry time.

Therefore split the timer storage into local pinned and global timers:
Local pinned timers are always expired on the CPU on which they have been
queued. Global timers can be expired on any CPU.

As long as a CPU is busy it expires both local and global timers. When a
CPU goes idle it arms for the first expiring local timer. If the first
expiring pinned (local) timer is before the first expiring movable timer,
then no action is required because the CPU will wake up before the first
movable timer expires. If the first expiring movable timer is before the
first expiring pinned (local) timer, then this timer is queued into an idle
timerqueue and eventually expired by another active CPU.

To avoid global locking the timerqueues are implemented as a hierarchy. The
lowest level of the hierarchy holds the CPUs. The CPUs are associated to
groups of 8, which are separated per node. If more than one CPU group
exist, then a second level in the hierarchy collects the groups. Depending
on the size of the system more than 2 levels are required. Each group has a
"migrator" which checks the timerqueue during the tick for remote expirable
timers.

If the last CPU in a group goes idle it reports the first expiring event in
the group up to the next group(s) in the hierarchy. If the last CPU goes
idle it arms its timer for the first system wide expiring timer to ensure
that no timer event is missed.

Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20240222103710.32582-1-anna-maria@linutronix.de

timers: Introduce function to check timer base is_idle flag

To prepare for the conversion of the NOHZ timer placement to a pull at
expiry time model it's required to have a function that returns the value
of the is_idle flag of the timer base to keep the hierarchy states during
online in sync with timer base state.

No functional change.

Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20240221090548.36600-18-anna-maria@linutronix.de

tick/sched: Split out jiffies update helper function

The logic to get the time of the last jiffies update will be needed by
the timer pull model as well.

Move the code into a global function in anticipation of the new caller.

No functional change.

Signed-off-by: Richard Cochran (linutronix GmbH) <richardcochran@gmail.com>
Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20240221090548.36600-17-anna-maria@linutronix.de

timers: Add get next timer interrupt functionality for remote CPUs

To prepare for the conversion of the NOHZ timer placement to a pull at
expiry time model it's required to have functionality available getting the
next timer interrupt on a remote CPU.

Locking of the timer bases and getting the information for the next timer
interrupt functionality is split into separate functions. This is required
to be compliant with lock ordering when the new model is in place.

Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20240221090548.36600-14-anna-maria@linutronix.de

timers: Move marking timer bases idle into tick_nohz_stop_tick()

The timer base is marked idle when get_next_timer_interrupt() is
executed. But the decision whether the tick will be stopped and whether the
system is able to go idle is done later. When the timer bases is marked
idle and a new first timer is enqueued remote an IPI is raised. Even if it
is not required because the tick is not stopped and the timer base is
evaluated again at the next tick.

To prevent this, the timer base is marked idle in tick_nohz_stop_tick() and
get_next_timer_interrupt() is streamlined by only looking for the next timer
interrupt. All other work is postponed to timer_base_try_to_set_idle() which is
called by tick_nohz_stop_tick(). timer_base_try_to_set_idle() never resets
timer_base::is_idle state. This is done when the tick is restarted via
tick_nohz_restart_sched_tick().

With this, tick_sched::tick_stopped and timer_base::is_idle are always in
sync. So there is no longer the need to execute timer_clear_idle() in
tick_nohz_idle_retain_tick(). This was required before, as
tick_nohz_next_event() set timer_base::is_idle even if the tick would not be
stopped. So timer_clear_idle() is only executed, when timer base is idle. So the
check whether timer base is idle, is now no longer required as well.

While at it fix some nearby whitespace damage as well.

Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20240221090548.36600-4-anna-maria@linutronix.de

time: Make sysfs_get_uname() function visible in header

This function is defined globally in clocksource.c and used conditionally
in clockevent.c, which the declaration hidden when clockevent support
is disabled. This causes a harmless warning in the definition:

kernel/time/clocksource.c:1324:9: warning: no previous prototype for 'sysfs_get_uname' [-Wmissing-prototypes]
1324 | ssize_t sysfs_get_uname(const char *buf, char *dst, size_t cnt)

Move the declaration out of the #ifdef so it is always visible.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20231108125843.3806765-5-arnd@kernel.org

clocksource: Make clocksource watchdog test safe for slow-HZ systems

The clocksource watchdog test sets a local JIFFIES_SHIFT macro and assumes
that HZ is >= 100. For smaller HZ values this shift value is too large and
causes undefined behaviour.

Move the HZ-based definitions of JIFFIES_SHIFT from kernel/time/jiffies.c
to kernel/time/tick-internal.h so the clocksource watchdog test can utilize
them, which makes it work correctly with all HZ values.

[ tglx: Resolved conflicts and massaged changelog ]

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/lkml/20210812000133.GA402890@paulmck-ThinkPad-P17-Gen-1/

hrtimer: Add bases argument to clock_was_set()

clock_was_set() unconditionaly invokes retrigger_next_event() on all online
CPUs. This was necessary because that mechanism was also used for resume
from suspend to idle which is not longer the case.

The bases arguments allows the callers of clock_was_set() to hand in a mask
which tells clock_was_set() which of the hrtimer clock bases are affected
by the clock setting. This mask will be used in the next step to check
whether a CPU base has timers queued on a clock base affected by the event
and avoid the SMP function call if there are none.

Add a @bases argument, provide defines for the active bases masking and
fixup all callsites.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210713135158.691083465@linutronix.de

timekeeping: Distangle resume and clock-was-set events

Resuming timekeeping is a clock-was-set event and uses the clock-was-set
notification mechanism. This is in the way of making the clock-was-set
update for hrtimers selective so unnecessary IPIs are avoided when a CPU
base does not have timers queued which are affected by the clock setting.

Distangle it by invoking hrtimer_resume() on each unfreezing CPU and invoke
the new timerfd_resume() function from timekeeping_resume() which is the
only place where this is needed.

Rename hrtimer_resume() to hrtimer_resume_local() to reflect the change.

With this the clock_was_set*() functions are not longer required to IPI all
CPUs unconditionally and can get some smarts to avoid them.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210713135158.488853478@linutronix.de

hrtimer: Ensure timerfd notification for HIGHRES=n

If high resolution timers are disabled the timerfd notification about a
clock was set event is not happening for all cases which use
clock_was_set_delayed() because that's a NOP for HIGHRES=n, which is wrong.

Make clock_was_set_delayed() unconditially available to fix that.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210713135158.196661266@linutronix.de

timer_list: Print name of per-cpu wakeup device

With the introduction of per-cpu wakeup devices that can be used in
preference to the broadcast timer, print the name of such devices when
they are available.

Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210524221818.15850-6-will@kernel.org

tick/broadcast: Prefer per-cpu oneshot wakeup timers to broadcast

Some SoCs have two per-cpu timer implementations where the timer with the
higher rating stops in deep idle (i.e. suffers from CLOCK_EVT_FEAT_C3STOP)
but is otherwise preferable to the timer with the lower rating. In such a
design, selecting the higher rated devices relies on a global broadcast
timer and IPIs to wake up from deep idle states.

To avoid the reliance on a global broadcast timer and also to reduce the
overhead associated with the IPI wakeups, extend
tick_install_broadcast_device() to manage per-cpu wakeup timers separately
from the broadcast device.

For now, these timers remain unused.

Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210524221818.15850-4-will@kernel.org

tick: Get rid of tick_period

The variable tick_period is initialized to NSEC_PER_TICK / HZ during boot
and never updated again.

If NSEC_PER_TICK is not an integer multiple of HZ this computation is less
accurate than TICK_NSEC which has proper rounding in place.

Aside of the inaccuracy there is no reason for having this variable at
all. It's just a pointless indirection and all usage sites can just use the
TICK_NSEC constant.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20201117132006.766643526@linutronix.de

tick: Remove outgoing CPU from broadcast masks

Valentin reported that unplugging a CPU occasionally results in a warning
in the tick broadcast code which is triggered when an offline CPU is in the
broadcast mask.

This happens because the outgoing CPU is not removing itself from the
broadcast masks, especially not from the broadcast_force_mask. The removal
happens on the control CPU after the outgoing CPU is dead. It's a long
standing issue, but the warning is harmless.

Rework the hotplug mechanism so that the outgoing CPU removes itself from
the broadcast masks after disabling interrupts and removing itself from the
online mask.

Reported-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Valentin Schneider <valentin.schneider@arm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1903211540180.1784@nanos.tec.linutronix.de

Revert: Unify CLOCK_MONOTONIC and CLOCK_BOOTTIME

Revert commits

92af4dcb4e1c ("tracing: Unify the "boot" and "mono" tracing clocks")
127bfa5f4342 ("hrtimer: Unify MONOTONIC and BOOTTIME clock behavior")
7250a4047aa6 ("posix-timers: Unify MONOTONIC and BOOTTIME clock behavior")
d6c7270e913d ("timekeeping: Remove boot time specific code")
f2d6fdbfd238 ("Input: Evdev - unify MONOTONIC and BOOTTIME clock behavior")
d6ed449afdb3 ("timekeeping: Make the MONOTONIC clock behave like the BOOTTIME clock")
72199320d49d ("timekeeping: Add the new CLOCK_MONOTONIC_ACTIVE clock")

As stated in the pull request for the unification of CLOCK_MONOTONIC and
CLOCK_BOOTTIME, it was clear that we might have to revert the change.

As reported by several folks systemd and other applications rely on the
documented behaviour of CLOCK_MONOTONIC on Linux and break with the above
changes. After resume daemons time out and other timeout related issues are
observed. Rafael compiled this list:

* systemd kills daemons on resume, after >WatchdogSec seconds
of suspending (Genki Sky). [Verified that that's because systemd uses
CLOCK_MONOTONIC and expects it to not include the suspend time.]

* systemd-journald misbehaves after resume:
systemd-journald[7266]: File /var/log/journal/016627c3c4784cd4812d4b7e96a34226/system.journal
corrupted or uncleanly shut down, renaming and replacing.
(Mike Galbraith).

* NetworkManager reports "networking disabled" and networking is broken
after resume 50% of the time (Pavel). [May be because of systemd.]

* MATE desktop dims the display and starts the screensaver right after
system resume (Pavel).

* Full system hang during resume (me). [May be due to systemd or NM or both.]

That happens on debian and open suse systems.

It's sad, that these problems were neither catched in -next nor by those
folks who expressed interest in this change.

Reported-by: Rafael J. Wysocki <rjw@rjwysocki.net>
Reported-by: Genki Sky <sky@genki.is>,
Reported-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kevin Easton <kevin@guarana.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Salyzyn <salyzyn@android.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>

timekeeping: Make the MONOTONIC clock behave like the BOOTTIME clock

The MONOTONIC clock is not fast forwarded by the time spent in suspend on
resume. This is only done for the BOOTTIME clock. The reason why the
MONOTONIC clock is not forwarded is historical: the original Linux
implementation was using jiffies as a base for the MONOTONIC clock and
jiffies have never been advanced after resume.

At some point when timekeeping was unified in the core code, the
MONONOTIC clock was advanced after resume which also advanced jiffies causing
interesting side effects. As a consequence the the MONOTONIC clock forwarding
was disabled again and the BOOTTIME clock was introduced, which allows to read
time since boot.

Back then it was not possible to completely distangle the MONOTONIC clock and
jiffies because there were still interfaces which exposed the MONOTONIC clock
behaviour based on the timer wheel and therefore jiffies.

As of today none of the MONOTONIC clock facilities depends on jiffies
anymore so the forwarding can be done seperately. This is achieved by
forwarding the variables which are used for the jiffies update after resume
before the tick is restarted,

In timekeeping resume, the change is rather simple. Instead of updating the
offset between the MONOTONIC clock and the REALTIME/BOOTTIME clocks, advance the
time keeper base for the MONOTONIC and the MONOTONIC_RAW clocks by the time
spent in suspend.

The MONOTONIC clock is now the same as the BOOTTIME clock and the offset between
the REALTIME and the MONOTONIC clocks is the same as before suspend.

There might be side effects in applications, which rely on the
(unfortunately) well documented behaviour of the MONOTONIC clock, but the
downsides of the existing behaviour are probably worse.

There is one obvious issue. Up to now it was possible to retrieve the time
spent in suspend by observing the delta between the MONOTONIC clock and the
BOOTTIME clock. This is not longer available, but the previously introduced
mechanism to read the active non-suspended monotonic time can mitigate that
in a detectable fashion.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kevin Easton <kevin@guarana.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Salyzyn <salyzyn@android.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20180301165150.062975504@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

hrtimer: Unify remote enqueue handling

hrtimer_reprogram() is conditionally invoked from hrtimer_start_range_ns()
when hrtimer_cpu_base.hres_active is true.

In the !hres_active case there is a special condition for the nohz_active
case:

If the newly enqueued timer expires before the first expiring timer on a
remote CPU then the remote CPU needs to be notified and woken up from a
NOHZ idle sleep to take the new first expiring timer into account.

Previous changes have already established the prerequisites to make the
remote enqueue behaviour the same whether high resolution mode is active or
not:

If the to be enqueued timer expires before the first expiring timer on a
remote CPU, then it cannot be enqueued there.

This was done for the high resolution mode because there is no way to
access the remote CPU timer hardware. The same is true for NOHZ, but was
handled differently by unconditionally enqueuing the timer and waking up
the remote CPU so it can reprogram its timer. Again there is no compelling
reason for this difference.

hrtimer_check_target(), which makes the 'can remote enqueue' decision is
already unconditional, but not yet functional because nothing updates
hrtimer_cpu_base.expires_next in the !hres_active case.

To unify this the following changes are required:

1) Make the store of the new first expiry time unconditonal in
hrtimer_reprogram() and check __hrtimer_hres_active() before proceeding
to the actual hardware access. This check also lets the compiler
eliminate the rest of the function in case of CONFIG_HIGH_RES_TIMERS=n.

2) Invoke hrtimer_reprogram() unconditionally from
hrtimer_start_range_ns()

3) Remove the remote wakeup special case for the !high_res && nohz_active
case.

Confine the timers_nohz_active static key to timer.c which is the only user
now.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: keescook@chromium.org
Link: http://lkml.kernel.org/r/20171221104205.7269-21-anna-maria@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

hrtimer: Optimize the hrtimer code by using static keys for migration_enable/nohz_active

The hrtimer_cpu_base::migration_enable and ::nohz_active fields
were originally introduced to avoid accessing global variables
for these decisions.

Still that results in a (cache hot) load and conditional branch,
which can be avoided by using static keys.

Implement it with static keys and optimize for the most critical
case of high performance networking which tends to disable the
timer migration functionality.

No change in functionality.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: keescook@chromium.org
Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1801142327490.2371@nanos
Link: https://lkml.kernel.org/r/20171221104205.7269-2-anna-maria@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

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 <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

tick/broadcast: Make tick_broadcast_setup_oneshot() static

This function isn't used outside of tick-broadcast.c, so let's
mark it static.

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Link: http://lkml.kernel.org/r/20170608063603.13276-1-sboyd@codeaurora.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

timers: Forward the wheel clock whenever possible

The wheel clock is stale when a CPU goes into a long idle sleep. This has the
side effect that timers which are queued end up in the outer wheel levels.
That results in coarser granularity.

To solve this, we keep track of the idle state and forward the wheel clock
whenever possible.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Chris Mason <clm@fb.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: George Spelvin <linux@sciencehorizons.net>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160704094342.512039360@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

timer: Minimize nohz off overhead

If nohz is disabled on the kernel command line the [hr]timer code
still calls wake_up_nohz_cpu() and tick_nohz_full_cpu(), a pretty
pointless exercise. Cache nohz_active in [hr]timer per cpu bases and
avoid the overhead.

Before:
48.10% hog [.] main
15.25% [kernel] [k] _raw_spin_lock_irqsave
9.76% [kernel] [k] _raw_spin_unlock_irqrestore
6.50% [kernel] [k] mod_timer
6.44% [kernel] [k] lock_timer_base.isra.38
3.87% [kernel] [k] detach_if_pending
3.80% [kernel] [k] del_timer
2.67% [kernel] [k] internal_add_timer
1.33% [kernel] [k] __internal_add_timer
0.73% [kernel] [k] timerfn
0.54% [kernel] [k] wake_up_nohz_cpu

After:
48.73% hog [.] main
15.36% [kernel] [k] _raw_spin_lock_irqsave
9.77% [kernel] [k] _raw_spin_unlock_irqrestore
6.61% [kernel] [k] lock_timer_base.isra.38
6.42% [kernel] [k] mod_timer
3.90% [kernel] [k] detach_if_pending
3.76% [kernel] [k] del_timer
2.41% [kernel] [k] internal_add_timer
1.39% [kernel] [k] __internal_add_timer
0.76% [kernel] [k] timerfn

We probably should have a cached value for nohz full in the per cpu
bases as well to avoid the cpumask check. The base cache line is hot
already, the cpumask not necessarily.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Joonwoo Park <joonwoop@codeaurora.org>
Cc: Wenbo Wang <wenbo.wang@memblaze.com>
Link: http://lkml.kernel.org/r/20150526224512.207378134@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

timer: Reduce timer migration overhead if disabled

Eric reported that the timer_migration sysctl is not really nice
performance wise as it needs to check at every timer insertion whether
the feature is enabled or not. Further the check does not live in the
timer code, so we have an extra function call which checks an extra
cache line to figure out that it is disabled.

We can do better and store that information in the per cpu (hr)timer
bases. I pondered to use a static key, but that's a nightmare to
update from the nohz code and the timer base cache line is hot anyway
when we select a timer base.

The old logic enabled the timer migration unconditionally if
CONFIG_NO_HZ was set even if nohz was disabled on the kernel command
line.

With this modification, we start off with migration disabled. The user
visible sysctl is still set to enabled. If the kernel switches to NOHZ
migration is enabled, if the user did not disable it via the sysctl
prior to the switch. If nohz=off is on the kernel command line,
migration stays disabled no matter what.

Before:
47.76% hog [.] main
14.84% [kernel] [k] _raw_spin_lock_irqsave
9.55% [kernel] [k] _raw_spin_unlock_irqrestore
6.71% [kernel] [k] mod_timer
6.24% [kernel] [k] lock_timer_base.isra.38
3.76% [kernel] [k] detach_if_pending
3.71% [kernel] [k] del_timer
2.50% [kernel] [k] internal_add_timer
1.51% [kernel] [k] get_nohz_timer_target
1.28% [kernel] [k] __internal_add_timer
0.78% [kernel] [k] timerfn
0.48% [kernel] [k] wake_up_nohz_cpu

After:
48.10% hog [.] main
15.25% [kernel] [k] _raw_spin_lock_irqsave
9.76% [kernel] [k] _raw_spin_unlock_irqrestore
6.50% [kernel] [k] mod_timer
6.44% [kernel] [k] lock_timer_base.isra.38
3.87% [kernel] [k] detach_if_pending
3.80% [kernel] [k] del_timer
2.67% [kernel] [k] internal_add_timer
1.33% [kernel] [k] __internal_add_timer
0.73% [kernel] [k] timerfn
0.54% [kernel] [k] wake_up_nohz_cpu


Reported-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Joonwoo Park <joonwoop@codeaurora.org>
Cc: Wenbo Wang <wenbo.wang@memblaze.com>
Link: http://lkml.kernel.org/r/20150526224512.127050787@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

clockevents: Rename state to state_use_accessors

The only sensible way to make abuse of core internal fields obvious
and easy to grep for.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>

clockevents: Provide functions to set and get the state

We want to rename dev->state, so provide proper get and set
functions. Rename clockevents_set_state() to
clockevents_switch_state() to avoid confusion.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>

tick: Nohz: Rework next timer evaluation

The evaluation of the next timer in the nohz code is based on jiffies
while all the tick internals are nano seconds based. We have also to
convert hrtimer nanoseconds to jiffies in the !highres case. That's
just wrong and introduces interesting corner cases.

Turn it around and convert the next timer wheel timer expiry and the
rcu event to clock monotonic and base all calculations on
nanoseconds. That identifies the case where no timer is pending
clearly with an absolute expiry value of KTIME_MAX.

Makes the code more readable and gets rid of the jiffies magic in the
nohz code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Link: http://lkml.kernel.org/r/20150414203502.184198593@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

clockevents: Cleanup dead cpu explicitely

clockevents_notify() is a leftover from the early design of the
clockevents facility. It's really not a notification mechanism,
it's a multiplex call. We are way better off to have explicit
calls instead of this monstrosity.

Split out the cleanup function for a dead cpu and invoke it
directly from the cpu down code. Make it conditional on
CPU_HOTPLUG as well.

Temporary change, will be refined in the future.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[ Rebased, added clockevents_notify() removal ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1735025.raBZdQHM3m@vostro.rjw.lan
Signed-off-by: Ingo Molnar <mingo@kernel.org>

clockevents: Make tick handover explicit

clockevents_notify() is a leftover from the early design of the
clockevents facility. It's really not a notification mechanism,
it's a multiplex call. We are way better off to have explicit
calls instead of this monstrosity.

Split out the tick_handover call and invoke it explicitely from
the hotplug code. Temporary solution will be cleaned up in later
patches.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[ Rebase ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/1658173.RkEEILFiQZ@vostro.rjw.lan
Signed-off-by: Ingo Molnar <mingo@kernel.org>

clockevents: Provide explicit broadcast oneshot control functions

clockevents_notify() is a leftover from the early design of the
clockevents facility. It's really not a notification mechanism,
it's a multiplex call. We are way better off to have explicit
calls instead of this monstrosity.

Split out the broadcast oneshot control into a separate function
and provide inline helpers. Switch clockevents_notify() over.
This will go away once all callers are converted.

This also gets rid of the nested locking of clockevents_lock and
broadcast_lock. The broadcast oneshot control functions do not
require clockevents_lock. Only the managing functions
(setup/shutdown/suspend/resume of the broadcast device require
clockevents_lock.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Alexandre Courbot <gnurou@gmail.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Warren <swarren@wwwdotorg.org>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Tony Lindgren <tony@atomide.com>
Link: http://lkml.kernel.org/r/13000649.8qZuEDV0OA@vostro.rjw.lan
Signed-off-by: Ingo Molnar <mingo@kernel.org>

clockevents: Provide explicit broadcast control functions

clockevents_notify() is a leftover from the early design of the
clockevents facility. It's really not a notification mechanism,
it's a multiplex call. We are way better off to have explicit
calls instead of this monstrosity.

Split out the broadcast control into a separate function and
provide inline helpers. Switch clockevents_notify() over. This
will go away once all callers are converted.

This also gets rid of the nested locking of clockevents_lock and
broadcast_lock. The broadcast control functions do not require
clockevents_lock. Only the managing functions
(setup/shutdown/suspend/resume of the broadcast device require
clockevents_lock.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tony Lindgren <tony@atomide.com>
Link: http://lkml.kernel.org/r/8086559.ttsuS0n1Xr@vostro.rjw.lan
Signed-off-by: Ingo Molnar <mingo@kernel.org>

tick: Further simplify tick-internal.h

Move the broadcasting related section to the GENERIC_CLOCKEVENTS=y
section - this also solves build failures on architectures that
don't use generic clockevents yet.

Also standardize include file style to make it easier to read, and
use nesting depth aware preprocessor directives to make future merges
easier.

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arm/bL_switcher: Kill tick suspend hackery

Use the new tick_suspend/resume_local() and get rid of the
homebrewn implementation of these in the ARM bL switcher. The
check for the cpumask is completely pointless. There is no harm
to suspend a per cpu tick device unconditionally. If that's a
real issue then we fix it proper at the core level and not with
some completely undocumented hacks in some random core code.

Move the tick internals to the core code, now that this nuisance
is gone.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[ rjw: Rebase, changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Link: http://lkml.kernel.org/r/1655112.Ws17YsMfN7@vostro.rjw.lan
Signed-off-by: Ingo Molnar <mingo@kernel.org>

tick/xen: Provide and use tick_suspend_local() and tick_resume_local()

Xen calls on every cpu into tick_resume() which is just wrong.
tick_resume() is for the syscore global suspend/resume
invocation. What XEN really wants is a per cpu local resume
function.

Provide a tick_resume_local() function and use it in XEN.

Also provide a complementary tick_suspend_local() and modify
tick_unfreeze() and tick_freeze(), respectively, to use the
new local tick resume/suspend functions.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[ Combined two patches, rebased, modified subject/changelog. ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1698741.eezk9tnXtG@vostro.rjw.lan
[ Merged to latest timers/core. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>

tick: Make tick_resume_broadcast_oneshot() static

Solely used in tick-broadcast.c and the return value is
hardcoded 0. Make it static and void.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1689058.QkHYDJSRKu@vostro.rjw.lan
Signed-off-by: Ingo Molnar <mingo@kernel.org>

clockevents: Make suspend/resume calls explicit

clockevents_notify() is a leftover from the early design of the
clockevents facility. It's really not a notification mechanism,
it's a multiplex call.

We are way better off to have explicit calls instead of this
monstrosity. Split out the suspend/resume() calls and invoke
them directly from the call sites.

No locking required at this point because these calls happen
with interrupts disabled and a single cpu online.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[ Rebased on top of 4.0-rc5. ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/713674030.jVm1qaHuPf@vostro.rjw.lan
[ Rebased on top of latest timers/core. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>

tick: Move core only declarations and functions to core

No point to expose everything to the world. People just believe
such functions can be abused for whatever purposes. Sigh.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[ Rebased on top of 4.0-rc5 ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Nicolas Pitre <nico@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/28017337.VbCUc39Gme@vostro.rjw.lan
[ Merged to latest timers/core ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>

tick: Simplify tick-internal.h

tick-internal.h is pretty confusing as a lot of the stub inlines
are there several times.

Distangle the maze and make clear functional sections.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[ rjw: Subject ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/16068264.vcNp79HLaT@vostro.rjw.lan
Signed-off-by: Ingo Molnar <mingo@kernel.org>

tick: Move clocksource related stuff to timekeeping.h

Move clocksource related stuff to timekeeping.h and remove the
pointless include from ntp.c

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[ rjw: Subject ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/2714218.nM5AEfAHj0@vostro.rjw.lan
Signed-off-by: Ingo Molnar <mingo@kernel.org>

clockevents: Remove CONFIG_GENERIC_CLOCKEVENTS_BUILD

This option was for simpler migration to the clock events code.
Most architectures have been converted and the option has been
disfunctional as a standalone option for quite some time. Remove
it.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/5021859.jl9OC1medj@vostro.rjw.lan
Signed-off-by: Ingo Molnar <mingo@kernel.org>

clockevents: Handle tick device's resume separately

Upcoming patch will redefine possible states of a clockevent
device. The RESUME mode is a special case only for tick's
clockevent devices. In future it can be replaced by ->resume()
callback already available for clockevent devices.

Lets handle it separately so that clockevents_set_mode() only
handles states valid across all devices. This also renames
set_mode_resume() to tick_resume() to make it more explicit.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: linaro-kernel@lists.linaro.org
Cc: linaro-networking@linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/c1b0112410870f49e7bf06958e1483eac6c15e20.1425037853.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

nohz: Move nohz full init call to tick init

This way we unbloat a bit main.c and more importantly we initialize
nohz full after init_IRQ(). This dependency will be needed in further
patches because nohz full needs irq work to raise its own IRQ.
Information about the support for this ability on ARM64 is obtained on
init_IRQ() which initialize the pointer to __smp_call_function.

Since tick_init() is called right after init_IRQ(), this is a good place
to call tick_nohz_init() and prepare for that dependency.

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

time: Consolidate the time accessor prototypes

Right now we have time related prototypes in 3 different header
files. Move it to a single timekeeping header file and move the core
internal stuff into a core private header.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>

time: Fixup fallout from recent clockevent/tick changes

Make the stub function static inline instead of static and move the
clockevents related function into the proper ifdeffed section.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Soren Brinkmann <soren.brinkmann@xilinx.com>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>

time: Change the return type of clockevents_notify() to integer

The broadcast framework can potentially be made use of by archs which do not have an
external clock device as well. Then, it is required that one of the CPUs need
to handle the broadcasting of wakeup IPIs to the CPUs in deep idle. As a
result its local timers should remain functional all the time. For such
a CPU, the BROADCAST_ENTER notification has to fail indicating that its clock
device cannot be shutdown. To make way for this support, change the return
type of tick_broadcast_oneshot_control() and hence clockevents_notify() to
indicate such scenarios.

Signed-off-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: deepthi@linux.vnet.ibm.com
Cc: paulmck@linux.vnet.ibm.com
Cc: fweisbec@gmail.com
Cc: paulus@samba.org
Cc: srivatsa.bhat@linux.vnet.ibm.com
Cc: svaidy@linux.vnet.ibm.com
Cc: peterz@infradead.org
Cc: benh@kernel.crashing.org
Cc: rafael.j.wysocki@intel.com
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/20140207080606.17187.78306.stgit@preeti.in.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

clockevents: Serialize calls to clockevents_update_freq() in the core

We can identify the broadcast device in the core and serialize all
callers including interrupts on a different CPU against the update.
Also, disabling interrupts is moved into the core allowing callers to
leave interrutps enabled when calling clockevents_update_freq().

Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Soeren Brinkmann <soren.brinkmann@xilinx.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Michal Simek <michal.simek@xilinx.com>
Link: http://lkml.kernel.org/r/1391466877-28908-2-git-send-email-soren.brinkmann@xilinx.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

tick/timekeeping: Call update_wall_time outside the jiffies lock

Since the xtime lock was split into the timekeeping lock and
the jiffies lock, we no longer need to call update_wall_time()
while holding the jiffies lock.

Thus, this patch splits update_wall_time() out from do_timer().

This allows us to get away from calling clock_was_set_delayed()
in update_wall_time() and instead use the standard clock_was_set()
call that previously would deadlock, as it causes the jiffies lock
to be acquired.

Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>

nohz: Convert a few places to use local per cpu accesses

A few functions use remote per CPU access APIs when they
deal with local values.

Just do the right conversion to improve performance, code
readability and debug checks.

While at it, lets extend some of these function names with *_this_cpu()
suffix in order to display their purpose more clearly.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>

time: Fix signedness bug in sysfs_get_uname() and its callers

sysfs_get_uname() is erroneously declared as returning size_t even
though it may return a negative value, specifically -EINVAL. Its
callers then check whether its return value is less than zero and indeed
that is never the case for size_t.

This patch changes sysfs_get_uname() to return ssize_t and makes sure
its callers use ssize_t accordingly.

Signed-off-by: Patrick Palka <patrick@parcs.ath.cx>
[jstultz: Didn't apply cleanly, as a similar partial fix was also applied
so had to resolve the collisions]
Signed-off-by: John Stultz <john.stultz@linaro.org>

clockevents: Define CS_NAME_LEN unconditionally

Unbreak architectures which do not use clockevents, but require to
build some of the core timekeeping infrastructure

Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

clockevents: Implement unbind functionality

Provide a sysfs interface to allow unbinding of clockevent
devices. The device is unbound if it is unused or if there is a
replacement device available. Unbinding of broadcast devices is not
supported as we don't want to foster that nonsense. If no replacement
device is available the unbind returns -EBUSY. Unbind is available
from the kernel and through sysfs, which is necessary to drop the
module refcount.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143436.499216659@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

clockevents: Move the tick_notify() switch case to clockevents_notify()

No need to call another function and have duplicated cases.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143436.235746557@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

clockevents: Get rid of the notifier chain

7+ years and still a single user. Kill it.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143436.098520211@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

timekeeping: Make jiffies_lock internal

Nothing outside of the timekeeping core needs that lock.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>

tick: Convert broadcast cpu bitmaps to cpumask_var_t

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20130306111537.366394000@linutronix.de
Cc: Rusty Russell <rusty@rustcorp.com.au>

time: Kill xtime_lock, replacing it with jiffies_lock

Now that timekeeping is protected by its own locks, rename
the xtime_lock to jifffies_lock to better describe what it
protects.

CC: Thomas Gleixner <tglx@linutronix.de>
CC: Eric Dumazet <eric.dumazet@gmail.com>
CC: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>

clockevents: Make minimum delay adjustments configurable

The automatic increase of the min_delta_ns of a clockevents device
should be done in the clockevents code as the minimum delay is an
attribute of the clockevents device.

In addition not all architectures want the automatic adjustment, on a
massively virtualized system it can happen that the programming of a
clock event fails several times in a row because the virtual cpu has
been rescheduled quickly enough. In that case the minimum delay will
erroneously be increased with no way back. The new config symbol
GENERIC_CLOCKEVENTS_MIN_ADJUST is used to enable the automatic
adjustment. The config option is selected only for x86.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: john stultz <johnstul@us.ibm.com>
Link: http://lkml.kernel.org/r/20110823133142.494157493@de.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

clockevents: Prevent oneshot mode when broadcast device is periodic

When the per cpu timer is marked CLOCK_EVT_FEAT_C3STOP, then we only
can switch into oneshot mode, when the backup broadcast device
supports oneshot mode as well. Otherwise we would try to switch the
broadcast device into an unsupported mode unconditionally. This went
unnoticed so far as the current available broadcast devices support
oneshot mode. Seth unearthed this problem while debugging and working
around an hpet related BIOS wreckage.

Add the necessary check to tick_is_oneshot_available().

Reported-and-tested-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
LKML-Reference: <alpine.LFD.2.00.1102252231200.2701@localhost6.localdomain6>
Cc: stable@kernel.org # .21 ->

time: Fix legacy arch fallout

The xtime/dotimer cleanup broke architectures which do not implement
clockevents. Time to send out another __do_IRQ threat.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reported-by: Ingo Molnar <mingo@elte.hu>
Cc: Torben Hohn <torbenh@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: johnstul@us.ibm.com
Cc: yong.zhang0@gmail.com
Cc: hch@infradead.org
LKML-Reference: <20110127145905.23248.30458.stgit@localhost>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

time: Make do_timer() and xtime_lock local to kernel/time/

All callers of do_timer() are converted to xtime_update(). The only
users of xtime_lock are in kernel/time/. Make both local to
kernel/time/ and remove them from the global header files.

[ tglx: Reuse tick-internal.h instead of creating another local header
file. Massaged changelog ]

Signed-off-by: Torben Hohn <torbenh@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: johnstul@us.ibm.com
Cc: yong.zhang0@gmail.com
Cc: hch@infradead.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

clockevents: Make tick_device_lock static

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Ingo Molnar <mingo@elte.hu>

NOHZ: restart tick device from irq_enter()

We did not restart the tick device from irq_enter() to avoid double
reprogramming and extra events in the return immediate to idle case.

But long lasting softirqs can lead to a situation where jiffies become
stale:

idle()
tick stopped (reprogrammed to next pending timer)
halt()
interrupt
jiffies updated from irq_enter()
interrupt handler
softirq function 1 runs 20ms
softirq function 2 arms a 10ms timer with a stale jiffies value
jiffies updated from irq_exit()
timer wheel has now an already expired timer
(the one added in function 2)
timer fires and timer softirq runs

This was discovered when debugging a timer problem which happend only
when the ath5k driver is active. The debugging proved that there is a
softirq function running for more than 20ms, which is a bug by itself.

To solve this we restart the tick timer right from irq_enter(), but do
not go through the other functions which are necessary to return from
idle when need_resched() is set.

Reported-by: Elias Oltmanns <eo@nebensachen.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Elias Oltmanns <eo@nebensachen.de>

timers: fix build error in !oneshot case

kernel/time/tick-common.c: In function ‘tick_setup_periodic’:
kernel/time/tick-common.c:113: error: implicit declaration of function ‘tick_broadcast_oneshot_active’

Signed-off-by: Ingo Molnar <mingo@elte.hu>

clockevents: prevent mode mismatch on cpu online

Impact: timer hang on CPU online observed on AMD C1E systems

When a CPU is brought online then the broadcast machinery can
be in the one shot state already. Check this and setup the timer
device of the new CPU in one shot mode so the broadcast code
can pick up the next_event value correctly.

Another AMD C1E oddity, as we switch to broadcast immediately and
not after the full bring up via the ACPI cpu idle code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

clockevents: prevent cpu online to interfere with nohz

Impact: rare hang which can be triggered on CPU online.

tick_do_timer_cpu keeps track of the CPU which updates jiffies
via do_timer. The value -1 is used to signal, that currently no
CPU is doing this. There are two cases, where the variable can
have this state:

boot:
necessary for systems where the boot cpu id can be != 0

nohz long idle sleep:
When the CPU which did the jiffies update last goes into
a long idle sleep it drops the update jiffies duty so
another CPU which is not idle can pick it up and keep
jiffies going.

Using the same value for both situations is wrong, as the CPU online
code can see the -1 state when the timer of the newly onlined CPU is
setup. The setup for a newly onlined CPU goes through periodic mode
and can pick up the do_timer duty without being aware of the nohz /
highres mode of the already running system.

Use two separate states and make them constants to avoid magic
numbers confusion.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

clockevents: make device shutdown robust

The device shut down does not cleanup the next_event variable of the
clock event device. So when the device is reactivated the possible
stale next_event value can prevent the device to be reprogrammed as it
claims to wait on a event already.

This is the root cause of the resurfacing suspend/resume problem,
where systems need key press to come back to life.

Fix this by setting next_event to KTIME_MAX when the device is shut
down. Use a separate function for shutdown which takes care of that
and only keep the direct set mode call in the broadcast code, where we
can not touch the next_event value.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

clockevents: prevent endless loop lockup

The C1E/HPET bug reports on AMDX2/RS690 systems where tracked down to a
too small value of the HPET minumum delta for programming an event.

The clockevents code needs to enforce an interrupt event on the clock event
device in some cases. The enforcement code was stupid and naive, as it just
added the minimum delta to the current time and tried to reprogram the device.
When the minimum delta is too small, then this loops forever.

Add a sanity check. Allow reprogramming to fail 3 times, then print a warning
and double the minimum delta value to make sure, that this does not happen again.
Use the same function for both tick-oneshot and tick-broadcast code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

timer: clean up tick-broadcast.c

clean up tick-broadcast.c

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

highres/dyntick: prevent xtime lock contention

While the !highres/!dyntick code assigns the duty of the do_timer() call to
one specific CPU, this was dropped in the highres/dyntick part during
development.

Steven Rostedt discovered the xtime lock contention on highres/dyntick due
to several CPUs trying to update jiffies.

Add the single CPU assignement back. In the dyntick case this needs to be
handled carefully, as the CPU which has the do_timer() duty must drop the
assignement and let it be grabbed by another CPU, which is active.
Otherwise the do_timer() calls would not happen during the long sleep.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Mark Lord <mlord@pobox.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

[PATCH] clockevents: Fix suspend/resume to disk hangs

I finally found a dual core box, which survives suspend/resume without
crashing in the middle of nowhere. Sigh, I never figured out from the
code and the bug reports what's going on.

The observed hangs are caused by a stale state transition of the clock
event devices, which keeps the RCU synchronization away from completion,
when the non boot CPU is brought back up.

The suspend/resume in oneshot mode needs the similar care as the
periodic mode during suspend to RAM. My assumption that the state
transitions during the different shutdown/bringups of s2disk would go
through the periodic boot phase and then switch over to highres resp.
nohz mode were simply wrong.

Add the appropriate suspend / resume handling for the non periodic
modes.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

[PATCH] Save/restore periodic tick information over suspend/resume

The programming of periodic tick devices needs to be saved/restored
across suspend/resume - otherwise we might end up with a system coming
up that relies on getting a PIT (or HPET) interrupt, while those devices
default to 'no interrupts' after powerup. (To confuse things it worked
to a certain degree on some systems because the lapic gets initialized
as a side-effect of SMP bootup.)

This suspend / resume thing was dropped unintentionally during the
last-minute -mm code reshuffling.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

[PATCH] tick-management: dyntick / highres functionality

With Ingo Molnar <mingo@elte.hu>

Add functions to provide dynamic ticks and high resolution timers. The code
which keeps track of jiffies and handles the long idle periods is shared
between tick based and high resolution timer based dynticks. The dyntick
functionality can be disabled on the kernel commandline. Provide also the
infrastructure to support high resolution timers.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

[PATCH] tick-management: broadcast functionality

With Ingo Molnar <mingo@elte.hu>

Add broadcast functionality, so per cpu clock event devices can be registered
as dummy devices or switched from/to broadcast on demand. The broadcast
function distributes the events via the broadcast function of the clock event
device. This is primarily designed to replace the switch apic timer to / from
IPI in power states, where the apic stops.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>