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The current implementation does not work if the thermal zone is
interrupt driven only.
The boundaries are not correctly checked and computed as it happens
only when the temperature is increasing or decreasing.
The problem arises because the routine to detect when we cross a
threshold is correlated with the computation of the boundaries. We
assume we have to recompute the boundaries when a threshold is crossed
but actually we should do that even if the it is not the case.
Mixing the boundaries computation and the threshold detection for the
sake of optimizing the routine is much more complex as it appears
intuitively and prone to errors.
This fix separates the boundaries computation and the threshold
crossing detection into different routines. The result is a code much
more simple to understand, thus easier to maintain.
The drawback is we browse the thresholds list several time but we can
consider that as neglictible because that happens when the temperature
is updated. There are certainly some aeras to improve in the
temperature update routine but it would be not adequate as this change
aims to fix the thresholds for v6.13.
Fixes: 445936f9e258 ("thermal: core: Add user thresholds support")
Tested-by: Daniel Lezcano <daniel.lezcano@linaro.org> # rock5b, Lenovo x13s
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://patch.msgid.link/20241216212644.1145122-1-daniel.lezcano@linaro.org
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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When the thermal zone is unregistered (thermal sensor module being
unloaded), no lock is held when flushing the thresholds. That results
in a WARN when the lockdep validation is set in the kernel config.
This has been reported by syzbot.
As the thermal zone is in the process of being destroyed, there is no
need to send a notification about purging the thresholds to the
userspace as this one will receive a thermal zone deletion
notification which imply the deletion of all the associated resources
like the trip points or the user thresholds.
Split the function thermal_thresholds_flush() into a lockless one
without notification and its call with the lock annotation followed
with the thresholds flushing notification.
Please note this scenario is unlikely to happen, as the sensor drivers
are usually compiled-in in order to have the thermal framework to be
able to kick in at boot time if needed.
Fixes: 445936f9e258 ("thermal: core: Add user thresholds support")
Link: https://lore.kernel.org/all/67124175.050a0220.10f4f4.0012.GAE@google.com
Reported-by: syzbot+f24dd060c1911fe54c85@syzkaller.appspotmail.com
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://patch.msgid.link/20241024102303.1086147-1-daniel.lezcano@linaro.org
[ rjw: Subject edit, added Fixes tag ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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The thresholds exist but there is no notification neither action code
related to them yet.
These changes implement the netlink for the notifications when the
thresholds are crossed, added, deleted or flushed as well as the
commands which allows to get the list of the thresholds, flush them,
add and delete.
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Link: https://patch.msgid.link/20241022155147.463475-3-daniel.lezcano@linaro.org
[ rjw: Use the thermal_zone guard for locking, subject edit ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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The user thresholds mechanism is a way to have the userspace to tell
the thermal framework to send a notification when a temperature limit
is crossed. There is no id, no hysteresis, just the temperature and
the direction of the limit crossing. That means we can be notified
when a threshold is crossed the way up only, or the way down only or
both ways. That allows to create hysteresis values if it is needed.
A threshold can be added, deleted or flushed. The latter means all
thresholds belonging to a thermal zone will be deleted.
When a threshold is added:
- if the same threshold (temperature and direction) exists, an error
is returned
- if a threshold is specified with the same temperature but a
different direction, the specified direction is added
- if there is no threshold with the same temperature then it is
created
When a threshold is deleted:
- if the same threshold (temperature and direction) exists, it is
deleted
- if a threshold is specified with the same temperature but a
different direction, the specified direction is removed
- if there is no threshold with the same temperature, then an error
is returned
When the threshold are flushed:
- All thresholds related to a thermal zone are deleted
When a threshold is crossed:
- the userspace does not need to know which threshold(s) have been
crossed, it will be notified with the current temperature and the
previous temperature
- if multiple thresholds have been crossed between two updates only
one notification will be send to the userspace, it is pointless to
send a notification per thresholds crossed as the userspace can
handle that easily when it has the temperature delta information
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://patch.msgid.link/20240923100005.2532430-2-daniel.lezcano@linaro.org
[ rjw: Subject edit, use BIT(0) and BIT(1) in symbol definitions ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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