linux/drivers/thermal/power_allocator.c, branch v4.9

thermal: fix race condition when updating cooling device

2016-08-08T02:57:39Z

When multiple thermal zones are bound to the same cooling device, multiple kernel threads may want to update the cooling device state by calling thermal_cdev_update(). Having cdev not protected by a mutex can lead to a race condition. Consider the following situation with two kernel threads k1 and k2: Thread k1 Thread k2 || || call thermal_cdev_update() || ... || set_cur_state(cdev, target); call power_actor_set_power() || ... || instance->target = state; || cdev->updated = false; || || cdev->updated = true; || // completes execution call thermal_cdev_update() || // cdev->updated == true || return; || \/ time k2 has already looped through the thermal instances looking for the deepest cooling device state and is preempted right before setting cdev->updated to true. Now, k1 runs, modifies the thermal instance state and sets cdev->updated to false. Then, k1 is preempted and k2 continues the execution by setting cdev->updated to true, therefore preventing k1 from performing the update. Notice that this is not an issue if k2 looks at the instance->target modified by k1 "after" it is assigned by k1. In fact, in this case the update will happen anyway and k1 can safely return immediately from thermal_cdev_update(). This may lead to a situation where a thermal governor never updates the cooling device. For example, this is the case for the step_wise governor: when calling the function thermal_zone_trip_update(), the governor may always get a new state equal to the old one (which, however, wasn't notified to the cooling device) and will therefore skip the update. CC: Zhang Rui CC: Eduardo Valentin CC: Peter Feuerer Reported-by: Toby Huang Signed-off-by: Michele Di Giorgio Reviewed-by: Javi Merino Signed-off-by: Zhang Rui

thermal: power_allocator: req_range multiplication should be a 64 bit type

2016-04-20T23:22:45Z

req_range is declared as a u64 to cope with overflows in the multiplication of two u32. As both req_power and power_range are u32, we need to make sure the multiplication is done with u64 types. Reported-by: Dan Carpenter Cc: Zhang Rui Cc: Eduardo Valentin Signed-off-by: Javi Merino Signed-off-by: Eduardo Valentin

thermal: power_allocator: Use temperature reading from tz

2015-11-12T18:47:24Z

All thermal governors use the temperature value stored in struct thermal_zone_device. thermal_zone_device->temperature power_allocator governor should not deviate from this and use the same. Cc: Javi Merino Cc: Eduardo Valentin Cc: Daniel Kurtz Cc: Zhang Rui Cc: Dmitry Torokhov Cc: Sascha Hauer Cc: Andrea Arcangeli Acked-by: Javi Merino Reported-by: Sugumar Natarajan Signed-off-by: Kapileshwar Singh Signed-off-by: Eduardo Valentin

remove abs64()

2015-11-09T23:11:24Z

Switch everything to the new and more capable implementation of abs(). Mainly to give the new abs() a bit of a workout. Cc: Michal Nazarewicz Cc: John Stultz Cc: Ingo Molnar Cc: Steven Rostedt Cc: Peter Zijlstra Cc: Masami Hiramatsu Cc: Peter Zijlstra Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

thermal: avoid division by zero in power allocator

2015-10-02T01:42:35Z

During boot I get a div by zero Oops regression starting in v4.3-rc3. Signed-off-by: Andrea Arcangeli Reviewed-by: Javi Merino Cc: Zhang Rui Cc: Eduardo Valentin Cc: Daniel Kurtz Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

thermal: power_allocator: exit early if there are no cooling devices

2015-09-20T07:37:16Z

Don't waste cycles in the power allocator governor's throttle function if there are no cooling devices and exit early. This commit doesn't change any functionality, but should provide better performance for the odd case of a thermal zone with trip points but without cooling devices. Cc: Zhang Rui Cc: Eduardo Valentin Reviewed-by: Daniel Kurtz Signed-off-by: Javi Merino Signed-off-by: Eduardo Valentin

thermal: power_allocator: don't require tzp to be present for the thermal zone

2015-09-14T14:43:15Z

Thermal zones created using thermal_zone_device_create() may not have tzp. As the governor gets its parameters from there, allocate it while the governor is bound to the thermal zone so that it can operate in it. In this case, tzp is freed when the thermal zone switches to another governor. Cc: Zhang Rui Cc: Eduardo Valentin Reviewed-by: Daniel Kurtz Signed-off-by: Javi Merino Signed-off-by: Eduardo Valentin

thermal: power_allocator: relax the requirement of two passive trip points

2015-09-14T14:41:45Z

The power allocator governor currently requires that the thermal zone has at least two passive trip points. If there aren't, the governor refuses to bind to the thermal zone. This commit relaxes that requirement. Now the governor will bind to all thermal zones regardless of how many trip points they have. Cc: Zhang Rui Cc: Eduardo Valentin Reviewed-by: Daniel Kurtz Signed-off-by: Javi Merino Signed-off-by: Eduardo Valentin

thermal: power_allocator: relax the requirement of a sustainable_power in tzp

2015-09-14T14:40:51Z

The power allocator governor currently requires that a sustainable power is passed as part of the thermal zone's thermal zone parameters. If that parameter is not provided, it doesn't register with the thermal zone. While this parameter is strongly recommended for optimal performance, it doesn't need to be mandatory. Relax the requirement and allow the governor to bind to thermal zones that don't provide it by estimating it from the cooling devices' power model. Cc: Zhang Rui Cc: Eduardo Valentin Reviewed-by: Daniel Kurtz Signed-off-by: Javi Merino Signed-off-by: Eduardo Valentin

Merge branches 'thermal-core' and 'thermal-intel' of .git into next

2015-09-02T02:08:02Z