reboot: retire hw_protection_reboot and hw_protection_shutdown helpers

The hw_protection_reboot and hw_protection_shutdown functions mix
mechanism with policy: They let the driver requesting an emer

reboot: retire hw_protection_reboot and hw_protection_shutdown helpers

The hw_protection_reboot and hw_protection_shutdown functions mix
mechanism with policy: They let the driver requesting an emergency action
for hardware protection also decide how to deal with it.

This is inadequate in the general case as a driver reporting e.g. an
imminent power failure can't know whether a shutdown or a reboot would be
more appropriate for a given hardware platform.

With the addition of the hw_protection parameter, it's now possible to
configure at runtime the default emergency action and drivers are expected
to use hw_protection_trigger to have this parameter dictate policy.

As no current users of either hw_protection_shutdown or
hw_protection_shutdown helpers remain, remove them, as not to tempt driver
authors to call them.

Existing users now either defer to hw_protection_trigger or call
__hw_protection_trigger with a suitable argument directly when they have
inside knowledge on whether a reboot or shutdown would be more
appropriate.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Ahmad Fatoum <[email protected]>
Reviewed-by: Tzung-Bi Shih <[email protected]>
Cc: Benson Leung <[email protected]>
Cc: Daniel Lezcano <[email protected]>
Cc: Fabio Estevam <[email protected]>
Cc: Guenter Roeck <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Liam Girdwood <[email protected]>
Cc: Lukasz Luba <[email protected]>
Cc: Mark Brown <[email protected]>
Cc: Matteo Croce <[email protected]>
Cc: Matti Vaittinen <[email protected]>
Cc: "Rafael J. Wysocki" <[email protected]>
Cc: Rob Herring (Arm) <[email protected]>
Cc: Rui Zhang <[email protected]>
Cc: Sascha Hauer <[email protected]>
Cc: "Serge E. Hallyn" <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

reboot: add support for configuring emergency hardware protection action

We currently leave the decision of whether to shutdown or reboot to
protect hardware in an emergency situation to the individ

reboot: add support for configuring emergency hardware protection action

We currently leave the decision of whether to shutdown or reboot to
protect hardware in an emergency situation to the individual drivers.

This works out in some cases, where the driver detecting the critical
failure has inside knowledge: It binds to the system management controller
for example or is guided by hardware description that defines what to do.

In the general case, however, the driver detecting the issue can't know
what the appropriate course of action is and shouldn't be dictating the
policy of dealing with it.

Therefore, add a global hw_protection toggle that allows the user to
specify whether shutdown or reboot should be the default action when the
driver doesn't set policy.

This introduces no functional change yet as hw_protection_trigger() has no
callers, but these will be added in subsequent commits.

[[email protected]: hide unused hw_protection_attr]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Ahmad Fatoum <[email protected]>
Reviewed-by: Tzung-Bi Shih <[email protected]>
Cc: Benson Leung <[email protected]>
Cc: Daniel Lezcano <[email protected]>
Cc: Fabio Estevam <[email protected]>
Cc: Guenter Roeck <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Liam Girdwood <[email protected]>
Cc: Lukasz Luba <[email protected]>
Cc: Mark Brown <[email protected]>
Cc: Matteo Croce <[email protected]>
Cc: Matti Vaittinen <[email protected]>
Cc: "Rafael J. Wysocki" <[email protected]>
Cc: Rob Herring (Arm) <[email protected]>
Cc: Rui Zhang <[email protected]>
Cc: Sascha Hauer <[email protected]>
Cc: "Serge E. Hallyn" <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

reboot: rename now misleading __hw_protection_shutdown symbols

The __hw_protection_shutdown function name has become misleading since it
can cause either a shutdown (poweroff) or a reboot depending

reboot: rename now misleading __hw_protection_shutdown symbols

The __hw_protection_shutdown function name has become misleading since it
can cause either a shutdown (poweroff) or a reboot depending on its
argument.

To avoid further confusion, let's rename it, so it doesn't suggest that a
poweroff is all it can do.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Ahmad Fatoum <[email protected]>
Reviewed-by: Tzung-Bi Shih <[email protected]>
Cc: Benson Leung <[email protected]>
Cc: Daniel Lezcano <[email protected]>
Cc: Fabio Estevam <[email protected]>
Cc: Guenter Roeck <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Liam Girdwood <[email protected]>
Cc: Lukasz Luba <[email protected]>
Cc: Mark Brown <[email protected]>
Cc: Matteo Croce <[email protected]>
Cc: Matti Vaittinen <[email protected]>
Cc: "Rafael J. Wysocki" <[email protected]>
Cc: Rob Herring (Arm) <[email protected]>
Cc: Rui Zhang <[email protected]>
Cc: Sascha Hauer <[email protected]>
Cc: "Serge E. Hallyn" <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

reboot: replace __hw_protection_shutdown bool action parameter with an enum

Patch series "reboot: support runtime configuration of emergency
hw_protection action", v3.

We currently leave the decisi

reboot: replace __hw_protection_shutdown bool action parameter with an enum

Patch series "reboot: support runtime configuration of emergency
hw_protection action", v3.

We currently leave the decision of whether to shutdown or reboot to
protect hardware in an emergency situation to the individual drivers.

This works out in some cases, where the driver detecting the critical
failure has inside knowledge: It binds to the system management controller
for example or is guided by hardware description that defines what to do.

This is inadequate in the general case though as a driver reporting e.g.
an imminent power failure can't know whether a shutdown or a reboot would
be more appropriate for a given hardware platform.

To address this, this series adds a hw_protection kernel parameter and
sysfs toggle that can be used to change the action from the shutdown
default to reboot. A new hw_protection_trigger API then makes use of this
default action.

My particular use case is unattended embedded systems that don't have
support for shutdown and that power on automatically when power is
supplied:

- A brief power cycle gets detected by the driver
- The kernel powers down the system and SoC goes into shutdown mode
- Power is restored
- The system remains oblivious to the restored power
- System needs to be manually power cycled for a duration long enough
to drain the capacitors

With this series, such systems can configure the kernel with
hw_protection=reboot to have the boot firmware worry about critical
conditions.


This patch (of 12):

Currently __hw_protection_shutdown() either reboots or shuts down the
system according to its shutdown argument.

To make the logic easier to follow, both inside __hw_protection_shutdown
and at caller sites, lets replace the bool parameter with an enum.

This will be extra useful, when in a later commit, a third action is added
to the enumeration.

No functional change.

Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Ahmad Fatoum <[email protected]>
Reviewed-by: Tzung-Bi Shih <[email protected]>
Cc: Benson Leung <[email protected]>
Cc: Mark Brown <[email protected]>
Cc: Daniel Lezcano <[email protected]>
Cc: Fabio Estevam <[email protected]>
Cc: Guenter Roeck <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Liam Girdwood <[email protected]>
Cc: Lukasz Luba <[email protected]>
Cc: Matteo Croce <[email protected]>
Cc: Matti Vaittinen <[email protected]>
Cc: "Rafael J. Wysocki" <[email protected]>
Cc: Rob Herring <[email protected]>
Cc: Rui Zhang <[email protected]>
Cc: Sascha Hauer <[email protected]>
Cc: "Serge E. Hallyn" <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

reboot: Introduce thermal_zone_device_critical_reboot()

Introduce thermal_zone_device_critical_reboot() to trigger an
emergency reboot.

It is a counterpart of thermal_zone_device_critical() with th

reboot: Introduce thermal_zone_device_critical_reboot()

Introduce thermal_zone_device_critical_reboot() to trigger an
emergency reboot.

It is a counterpart of thermal_zone_device_critical() with the
difference that it will force a reboot instead of shutdown.

The motivation for doing this is to allow the thermal subystem
to trigger a reboot when the temperature reaches the critical
temperature.

Signed-off-by: Fabio Estevam <[email protected]>
Signed-off-by: Daniel Lezcano <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

show more ...

thermal/core: Prepare for introduction of thermal reboot

Add some helper functions to make it easier introducing the support
for thermal reboot.

No functional change.

Signed-off-by: Fabio Estevam

thermal/core: Prepare for introduction of thermal reboot

Add some helper functions to make it easier introducing the support
for thermal reboot.

No functional change.

Signed-off-by: Fabio Estevam <[email protected]>
Signed-off-by: Daniel Lezcano <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

show more ...

kernel/reboot: Add device to sys_off_handler

If the dev is known (e.g. a devm-based sys_off_handler is used), it can
be passed to the handler's callback to have it available there.
Otherwise, cb_dat

kernel/reboot: Add device to sys_off_handler

If the dev is known (e.g. a devm-based sys_off_handler is used), it can
be passed to the handler's callback to have it available there.
Otherwise, cb_data might be set to the dev in most of the cases.

Reviewed-by: Dmitry Osipenko <[email protected]>
Signed-off-by: Benjamin Bara <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Lee Jones <[email protected]>

show more ...

kernel/reboot: Add SYS_OFF_MODE_RESTART_PREPARE mode

Add SYS_OFF_MODE_RESTART_PREPARE callbacks to be invoked before
a system restart.

Suggested-by: Dmitry Osipenko <[email protected]>

kernel/reboot: Add SYS_OFF_MODE_RESTART_PREPARE mode

Add SYS_OFF_MODE_RESTART_PREPARE callbacks to be invoked before
a system restart.

Suggested-by: Dmitry Osipenko <[email protected]>
Reviewed-by: Dmitry Osipenko <[email protected]>
Signed-off-by: Kai-Heng Feng <[email protected]>
[ rjw: Changelog edits ]
Signed-off-by: Rafael J. Wysocki <[email protected]>

show more ...

kernel/reboot: Add devm_register_restart_handler()

Add devm_register_restart_handler() helper that registers sys-off
handler using restart mode and with a default priority. Most drivers
will want to

kernel/reboot: Add devm_register_restart_handler()

Add devm_register_restart_handler() helper that registers sys-off
handler using restart mode and with a default priority. Most drivers
will want to register restart handler with a default priority, so this
helper will reduce the boilerplate code and make code easier to read and
follow.

Signed-off-by: Dmitry Osipenko <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>

show more ...

kernel/reboot: Add devm_register_power_off_handler()

Add devm_register_power_off_handler() helper that registers sys-off
handler using power-off mode and with a default priority. Most drivers
will w

kernel/reboot: Add devm_register_power_off_handler()

Add devm_register_power_off_handler() helper that registers sys-off
handler using power-off mode and with a default priority. Most drivers
will want to register power-off handler with a default priority, so this
helper will reduce the boilerplate code and make code easier to read and
follow.

Signed-off-by: Dmitry Osipenko <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>

show more ...

kernel/reboot: Add register_platform_power_off()

Add platform-level registration helpers that will ease transition of the
arch/platform power-off callbacks to the new sys-off based API, allowing
us

kernel/reboot: Add register_platform_power_off()

Add platform-level registration helpers that will ease transition of the
arch/platform power-off callbacks to the new sys-off based API, allowing
us to remove the global pm_power_off variable in the future.

Signed-off-by: Dmitry Osipenko <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>

show more ...

kernel/reboot: Add kernel_can_power_off()

Add kernel_can_power_off() helper that replaces open-coded checks of
the global pm_power_off variable. This is a necessary step towards
supporting chained p

kernel/reboot: Add kernel_can_power_off()

Add kernel_can_power_off() helper that replaces open-coded checks of
the global pm_power_off variable. This is a necessary step towards
supporting chained power-off handlers.

Signed-off-by: Dmitry Osipenko <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>

show more ...

kernel/reboot: Add do_kernel_power_off()

Add do_kernel_power_off() helper that will remove open-coded pm_power_off
invocations from the architecture code. This is the first step on the way
to remove

kernel/reboot: Add do_kernel_power_off()

Add do_kernel_power_off() helper that will remove open-coded pm_power_off
invocations from the architecture code. This is the first step on the way
to remove the global pm_power_off variable, which will allow us to
implement consistent power-off chaining support.

Signed-off-by: Dmitry Osipenko <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>

show more ...

kernel/reboot: Introduce sys-off handler API

In order to support power-off chaining we need to get rid of the global
pm_* variables, replacing them with the new kernel API functions that
support cha

kernel/reboot: Introduce sys-off handler API

In order to support power-off chaining we need to get rid of the global
pm_* variables, replacing them with the new kernel API functions that
support chaining.

Introduce new generic sys-off handler API that brings the following
features:

1. Power-off and restart handlers are registered using same API function
that supports chaining, hence all power-off and restart modes will
support chaining using this unified function.

2. Prevents notifier priority collisions by disallowing registration of
multiple handlers at the non-default priority level.

3. Supports passing opaque user argument to callback, which allows us to
remove global variables from drivers.

This patch adds support of the following sys-off modes:

- SYS_OFF_MODE_POWER_OFF_PREPARE that replaces global pm_power_off_prepare
variable and provides chaining support for power-off-prepare handlers.

- SYS_OFF_MODE_POWER_OFF that replaces global pm_power_off variable and
provides chaining support for power-off handlers.

- SYS_OFF_MODE_RESTART that provides a better restart API, removing a need
from drivers to have a global scratch variable by utilizing the opaque
callback argument.

Signed-off-by: Dmitry Osipenko <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>

show more ...

kernel/reboot: move reboot sysctls to its own file

kernel/sysctl.c is a kitchen sink where everyone leaves their dirty
dishes, this makes it very difficult to maintain.

To help with this maintenanc

kernel/reboot: move reboot sysctls to its own file

kernel/sysctl.c is a kitchen sink where everyone leaves their dirty
dishes, this makes it very difficult to maintain.

To help with this maintenance let's start by moving sysctls to places
where they actually belong. The proc sysctl maintainers do not want to
know what sysctl knobs you wish to add for your own piece of code, we
just care about the core logic.

All filesystem syctls now get reviewed by fs folks. This commit
follows the commit of fs, move the poweroff_cmd and ctrl-alt-del
sysctls to its own file, kernel/reboot.c.

Signed-off-by: tangmeng <[email protected]>
Signed-off-by: Luis Chamberlain <[email protected]>

show more ...

reboot: Add hardware protection power-off

There can be few cases when we need to shut-down the system in order to
protect the hardware. Currently this is done at least by the thermal core
when tempe

reboot: Add hardware protection power-off

There can be few cases when we need to shut-down the system in order to
protect the hardware. Currently this is done at least by the thermal core
when temperature raises over certain limit.

Some PMICs can also generate interrupts for example for over-current or
over-voltage, voltage drops, short-circuit, ... etc. On some systems
these are a sign of hardware failure and only thing to do is try to
protect the rest of the hardware by shutting down the system.

Add shut-down logic which can be used by all subsystems instead of
implementing the shutdown in each subsystem. The logic is stolen from
thermal_core with difference of using atomic_t instead of a mutex in
order to allow calls directly from IRQ context and changing the WARN()
to pr_emerg() as discussed here:
https://lore.kernel.org/lkml/YJuPwAZroVZ%2Fw633@alley/
and here:
https://lore.kernel.org/linux-iommu/[email protected]/

Signed-off-by: Matti Vaittinen <[email protected]>
Acked-by: Daniel Lezcano <[email protected]>
Link: https://lore.kernel.org/r/e83ec1ca9408f90c857ea9dcdc57b14d9037b03f.1622628333.git.matti.vaittinen@fi.rohmeurope.com
Signed-off-by: Mark Brown <[email protected]>

show more ...

panic/reboot: allow specifying reboot_mode for panic only

Allow specifying reboot_mode for panic only. This is needed on systems
where ramoops is used to store panic logs, and user wants to use war

panic/reboot: allow specifying reboot_mode for panic only

Allow specifying reboot_mode for panic only. This is needed on systems
where ramoops is used to store panic logs, and user wants to use warm
reset to preserve those, while still having cold reset on normal
reboots.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Aaro Koskinen <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

kernel/reboot.c: add devm_register_reboot_notifier()

Add devm_* wrapper around register_reboot_notifier to simplify device
specific reboot notifier registration/unregistration.

[akpm@linux-foundati

kernel/reboot.c: add devm_register_reboot_notifier()

Add devm_* wrapper around register_reboot_notifier to simplify device
specific reboot notifier registration/unregistration.

[[email protected]: move `struct device' forward decl to top-of-file]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Andrey Smirnov <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

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]>

show more ...

kernel/reboot.c: add orderly_reboot for graceful reboot

The kernel has orderly_poweroff which allows the kernel to initiate a
graceful shutdown of userspace, by running /sbin/poweroff. This adds
or

kernel/reboot.c: add orderly_reboot for graceful reboot

The kernel has orderly_poweroff which allows the kernel to initiate a
graceful shutdown of userspace, by running /sbin/poweroff. This adds
orderly_reboot that will cause userspace to shut itself down by calling
/sbin/reboot.

This will be used for shutdown initiated by a system controller on
platforms that do not use ACPI.

orderly_reboot() should be used when the system wants to allow userspace
to gracefully shut itself down. For cases where the system may imminently
catch on fire, the existing emergency_restart() provides an immediate
reboot without involving userspace.

Signed-off-by: Joel Stanley <[email protected]>
Cc: Fabian Frederick <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Rusty Russell <[email protected]>
Cc: Jeremy Kerr <[email protected]>
Cc: David S. Miller <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

kernel: add support for kernel restart handler call chain

Various drivers implement architecture and/or device specific means to
restart (reset) the system. Various mechanisms have been implemented

kernel: add support for kernel restart handler call chain

Various drivers implement architecture and/or device specific means to
restart (reset) the system. Various mechanisms have been implemented to
support those schemes. The best known mechanism is arm_pm_restart, which
is a function pointer to be set either from platform specific code or from
drivers. Another mechanism is to use hardware watchdogs to issue a reset;
this mechanism is used if there is no other method available to reset a
board or system. Two examples are alim7101_wdt, which currently uses the
reboot notifier to trigger a reset, and moxart_wdt, which registers the
arm_pm_restart function.

The existing mechanisms have a number of drawbacks. Typically only one
scheme to restart the system is supported (at least if arm_pm_restart is
used). At least in theory there can be multiple means to restart the
system, some of which may be less desirable (for example one mechanism may
only reset the CPU, while another may reset the entire system). Using
arm_pm_restart can also be racy if the function pointer is set from a
driver, as the driver may be in the process of being unloaded when
arm_pm_restart is called. Using the reboot notifier is always racy, as it
is unknown if and when other functions using the reboot notifier have
completed execution by the time the watchdog fires.

Introduce a system restart handler call chain to solve the described
problems. This call chain is expected to be executed from the
architecture specific machine_restart() function. Drivers providing
system restart functionality (such as the watchdog drivers mentioned
above) are expected to register with this call chain. By using the
priority field in the notifier block, callers can control restart handler
execution sequence and thus ensure that the restart handler with the
optimal restart capabilities for a given system is called first.

Signed-off-by: Guenter Roeck <[email protected]>
Acked-by: Catalin Marinas <[email protected]>
Acked-by: Heiko Stuebner <[email protected]>
Cc: Russell King <[email protected]>
Cc: Wim Van Sebroeck <[email protected]>
Cc: Maxime Ripard <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Jonas Jensen <[email protected]>
Cc: Randy Dunlap <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Dmitry Eremin-Solenikov <[email protected]>
Cc: David Woodhouse <[email protected]>
Cc: Tomasz Figa <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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x86: Remove the PCI reboot method from the default chain

Steve reported a reboot hang and bisected it back to this commit:

a4f1987e4c54 x86, reboot: Add EFI and CF9 reboot methods into the defaul

x86: Remove the PCI reboot method from the default chain

Steve reported a reboot hang and bisected it back to this commit:

a4f1987e4c54 x86, reboot: Add EFI and CF9 reboot methods into the default list

He heroically tested all reboot methods and found the following:

reboot=t # triple fault ok
reboot=k # keyboard ctrl FAIL
reboot=b # BIOS ok
reboot=a # ACPI FAIL
reboot=e # EFI FAIL [system has no EFI]
reboot=p # PCI 0xcf9 FAIL

And I think it's pretty obvious that we should only try PCI 0xcf9 as a
last resort - if at all.

The other observation is that (on this box) we should never try
the PCI reboot method, but close with either the 'triple fault'
or the 'BIOS' (terminal!) reboot methods.

Thirdly, CF9_COND is a total misnomer - it should be something like
CF9_SAFE or CF9_CAREFUL, and 'CF9' should be 'CF9_FORCE' ...

So this patch fixes the worst problems:

- it orders the actual reboot logic to follow the reboot ordering
pattern - it was in a pretty random order before for no good
reason.

- it fixes the CF9 misnomers and uses BOOT_CF9_FORCE and
BOOT_CF9_SAFE flags to make the code more obvious.

- it tries the BIOS reboot method before the PCI reboot method.
(Since 'BIOS' is a terminal reboot method resulting in a hang
if it does not work, this is essentially equivalent to removing
the PCI reboot method from the default reboot chain.)

- just for the miraculous possibility of terminal (resulting
in hang) reboot methods of triple fault or BIOS returning
without having done their job, there's an ordering between
them as well.

Reported-and-bisected-and-tested-by: Steven Rostedt <[email protected]>
Cc: Li Aubrey <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Matthew Garrett <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

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kexec: migrate to reboot cpu

Commit 1b3a5d02ee07 ("reboot: move arch/x86 reboot= handling to generic
kernel") moved reboot= handling to generic code. In the process it also
removed the code in nati

kexec: migrate to reboot cpu

Commit 1b3a5d02ee07 ("reboot: move arch/x86 reboot= handling to generic
kernel") moved reboot= handling to generic code. In the process it also
removed the code in native_machine_shutdown() which are moving reboot
process to reboot_cpu/cpu0.

I guess that thought must have been that all reboot paths are calling
migrate_to_reboot_cpu(), so we don't need this special handling. But
kexec reboot path (kernel_kexec()) is not calling
migrate_to_reboot_cpu() so above change broke kexec. Now reboot can
happen on non-boot cpu and when INIT is sent in second kerneo to bring
up BP, it brings down the machine.

So start calling migrate_to_reboot_cpu() in kexec reboot path to avoid
this problem.

Bisected by WANG Chao.

Reported-by: Matthew Whitehead <[email protected]>
Reported-by: Dave Young <[email protected]>
Signed-off-by: Vivek Goyal <[email protected]>
Tested-by: Baoquan He <[email protected]>
Tested-by: WANG Chao <[email protected]>
Acked-by: H. Peter Anvin <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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reboot: move arch/x86 reboot= handling to generic kernel

Merge together the unicore32, arm, and x86 reboot= command line
parameter handling.

Signed-off-by: Robin Holt <[email protected]>
Cc: H. Peter An

reboot: move arch/x86 reboot= handling to generic kernel

Merge together the unicore32, arm, and x86 reboot= command line
parameter handling.

Signed-off-by: Robin Holt <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Russell King <[email protected]>
Cc: Guan Xuetao <[email protected]>
Cc: Russ Anderson <[email protected]>
Cc: Robin Holt <[email protected]>
Acked-by: Ingo Molnar <[email protected]>
Acked-by: Guan Xuetao <[email protected]>
Acked-by: Russell King <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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reboot: arm: change reboot_mode to use enum reboot_mode

Preparing to move the parsing of reboot= to generic kernel code forces
the change in reboot_mode handling to use the enum.

[akpm@linux-founda

reboot: arm: change reboot_mode to use enum reboot_mode

Preparing to move the parsing of reboot= to generic kernel code forces
the change in reboot_mode handling to use the enum.

[[email protected]: fix arch/arm/mach-socfpga/socfpga.c]
Signed-off-by: Robin Holt <[email protected]>
Cc: Russell King <[email protected]>
Cc: Russ Anderson <[email protected]>
Cc: Robin Holt <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Guan Xuetao <[email protected]>
Acked-by: Russell King <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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