[ Upstream commit 4e814173a8c4f432fd068b1c796f0416328c9d99 ]

There are 3 synchronization issues with thermal zone suspend-resume
during system-wide transitions:

 1. The resume code runs in a PM notifier which is invoked after user
    space has been thawed, so it can run concurrently with user space
    which can trigger a thermal zone device removal.  If that happens,
    the thermal zone resume code may use a stale pointer to the next
    list element and crash, because it does not hold thermal_list_lock
    while walking thermal_tz_list.

 2. The thermal zone resume code calls thermal_zone_device_init()
    outside the zone lock, so user space or an update triggered by
    the platform firmware may see an inconsistent state of a
    thermal zone leading to unexpected behavior.

 3. Clearing the in_suspend global variable in thermal_pm_notify()
    allows __thermal_zone_device_update() to continue for all thermal
    zones and it may as well run before the thermal_tz_list walk (or
    at any point during the list walk for that matter) and attempt to
    operate on a thermal zone that has not been resumed yet.  It may
    also race destructively with thermal_zone_device_init().

To address these issues, add thermal_list_lock locking to
thermal_pm_notify(), especially arount the thermal_tz_list,
make it call thermal_zone_device_init() back-to-back with
__thermal_zone_device_update() under the zone lock and replace
in_suspend with per-zone bool "suspend" indicators set and unset
under the given zone's lock.

Link: https://lore.kernel.org/linux-pm/20231218162348.69101-1-bo.ye@mediatek.com/
Reported-by: Bo Ye <bo.ye@mediatek.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Modify the governor .throttle() callback definition so that it takes a
trip pointer instead of a trip index as its second argument, adjust the
governors accordingly and update the core code invoking .throttle().

This causes the governors to become independent of the representation
of the list of trips in the thermal zone structure.

This change is not expected to alter the general functionality.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Daniel Lezcano <daniel.lezcano@linaro.org>

Because thermal_zone_device_exec() has no users any more and there are
no plans to use it anywhere, revert commit 9a99a996d1ec ("thermal: core:
Introduce thermal_zone_device_exec()") that introduced it.

No functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>

Add a wrapper around for_each_thermal_trip(), called
thermal_zone_for_each_trip(), that will invoke the former under the
thermal zone lock and pass its return value to the caller.

Two drivers will be modified subsequently to use this new function.

No functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Daniel Lezcano <daniel.lezcano@linaro.org>

Add new helper functions, thermal_bind_cdev_to_trip() and
thermal_unbind_cdev_from_trip(), to allow a trip pointer to be used for
binding a cooling device to a trip point and unbinding it, respectively,
and redefine the existing helpers, thermal_zone_bind_cooling_device()
and thermal_zone_unbind_cooling_device(), as wrappers around the new
ones, respectively.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Daniel Lezcano <daniel.lezcano@linaro.org>

After recent changes, thermal_zone_get_trip() cannot fail, as invoked
from thermal_zone_device_register_with_trips(), so the only role of
the trips_disabled bitmask is struct thermal_zone_device is to make
handle_thermal_trip() skip trip points whose temperature was initially
zero.  However, since the unit of temperature in the thermal core is
millicelsius, zero may very well be a valid temperature value at least
in some usage scenarios and the trip temperature may as well change
later.  Thus there is no reason to permanently disable trip points
with initial temperature equal to zero.

Accordingly, drop the trips_disabled bitmask along with the code
related to it.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Ido Schimmel <idosch@nvidia.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>

Add 'const' to the definition of the 'trip' argument of the
.get_trend() thermal zone callback to indicate that the trip point
passed to it should not be modified by it and adjust the
callback functions implementing it, thermal_get_trend() in the
ACPI thermal driver and __ti_thermal_get_trend(), accordingly.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Michal Wilczynski <michal.wilczynski@intel.com>

There are no more users of thermal_zone_device_register(), so drop it
from the core.

Note that thermal_zone_device_register_with_trips() may be renamed to
thermal_zone_device_register() in the future, but only after a grace
period allowing all of the possible work in progress that may be using
the latter to adjust.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Multiple callers of thermal_zone_device_register() don't pass any trips
to it and they might use a shortened argument list for that, so add
a special function with fewer arguments for this purpose.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

For consistency, add a missing thermal_zone_device_register_with_trips()
stub for the CONFIG_THERMAL unset case, specify argument names in all of
the thermal zone registration and unregistration function headers and
make all of them use white space consistently.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>