linux-stable.git/kernel/power/qos.c, branch v6.2

PM: QoS: Add check to make sure CPU freq is non-negative

2022-07-26T18:48:33+00:00

CPU frequency should never be negative.

If some client driver calls freq_qos_update_request with a
negative value which will be very high in absolute terms,
then frequency QoS sets max CPU freq at fmax as it considers
it's absolute value but it will add plist node with negative
priority.

plist node has priority from INT_MIN (highest) to INT_MAX(lowest).
Once priority is set as negative, another client will not be able
to reduce CPU frequency.

Adding check to make sure CPU freq is non-negative will fix
this problem.

Signed-off-by: Shivnandan Kumar 
[ rjw: Changelog edits ]
Signed-off-by: Rafael J. Wysocki

treewide: Use fallthrough pseudo-keyword

2020-08-23T22:36:59+00:00

Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva

PM: QoS: annotate data races in pm_qos_*_value()

2020-03-03T22:34:51+00:00

The target_value field in struct pm_qos_constraints is used for
lockless access to the effective constraint value of a given QoS
list, so the readers of it cannot expect it to always reflect the
most recent effective constraint value.  However, they can and do
expect it to be equal to a valid effective constraint value computed
at a certain time in the past (event though it may not be the most
recent one), so add READ|WRITE_ONCE() annotations around the
target_value accesses to prevent the compiler from possibly causing
that expectation to be unmet by generating code in an exceptionally
convoluted way.

Signed-off-by: Qian Cai 
[ rjw: Changelog ]
Signed-off-by: Rafael J. Wysocki

PM: QoS: Make CPU latency QoS depend on CONFIG_CPU_IDLE

2020-02-14T09:37:27+00:00

Because cpuidle is the only user of the effective constraint coming
from the CPU latency QoS, add #ifdef CONFIG_CPU_IDLE around that code
to avoid building it unnecessarily.

Signed-off-by: Rafael J. Wysocki 
Reviewed-by: Ulf Hansson 
Reviewed-by: Amit Kucheria 
Tested-by: Amit Kucheria

PM: QoS: Update file information comments

2020-02-14T09:37:26+00:00

Update the file information comments in include/linux/pm_qos.h
and kernel/power/qos.c by adding titles along with copyright and
authors information to them and changing the qos.c description to
better reflect its contents (outdated information is dropped from
it in particular).

Signed-off-by: Rafael J. Wysocki 
Reviewed-by: Ulf Hansson 
Reviewed-by: Amit Kucheria 
Tested-by: Amit Kucheria

PM: QoS: Drop PM_QOS_CPU_DMA_LATENCY and rename related functions

2020-02-14T09:37:26+00:00

Drop the PM QoS classes enum including PM_QOS_CPU_DMA_LATENCY,
drop the wrappers around pm_qos_request(), pm_qos_request_active(),
and pm_qos_add/update/remove_request() introduced previously, rename
these functions, respectively, to cpu_latency_qos_limit(),
cpu_latency_qos_request_active(), and
cpu_latency_qos_add/update/remove_request(), and update their
kerneldoc comments.  [While at it, drop some useless comments from
these functions.]

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki 
Reviewed-by: Ulf Hansson 
Reviewed-by: Amit Kucheria 
Tested-by: Amit Kucheria

PM: QoS: Adjust pm_qos_request() signature and reorder pm_qos.h

2020-02-13T10:26:46+00:00

Change the return type of pm_qos_request() to be the same as the
one of pm_qos_read_value() called by it internally and stop exporting
it to modules (because its only caller, cpuidle, is not modular).

Also move the pm_qos_read_value() header away from the CPU latency
QoS API function headers in pm_qos.h (because it technically does
not belong to that API).

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki 
Reviewed-by: Ulf Hansson 
Reviewed-by: Amit Kucheria 
Tested-by: Amit Kucheria

PM: QoS: Simplify definitions of CPU latency QoS trace events

2020-02-13T10:26:39+00:00

Modify the definitions of the CPU latency QoS trace events to take
one argument (since PM_QOS_CPU_DMA_LATENCY is always passed as the
pm_qos_class argument to them) and update the documentation of them
accordingly (while at it, make it explicitly mention CPU latency QoS
and relocate it after the device PM QoS trace events documentation).

The names and output format of the trace events do not change to
preserve user space compatibility.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki 
Reviewed-by: Ulf Hansson 
Reviewed-by: Amit Kucheria 
Tested-by: Amit Kucheria

PM: QoS: Rename things related to the CPU latency QoS

2020-02-13T10:26:33+00:00

First, rename PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE to
PM_QOS_CPU_LATENCY_DEFAULT_VALUE and update all of the code
referring to it accordingly.

Next, rename cpu_dma_constraints to cpu_latency_constraints, move
the definition of it closer to the functions referring to it and
update all of them accordingly.  [While at it, add a comment to mark
the start of the code related to the CPU latency QoS.]

Finally, rename the pm_qos_power_*() family of functions and
pm_qos_power_fops to cpu_latency_qos_*() and cpu_latency_qos_fops,
respectively, and update the definition of cpu_latency_qos_miscdev.
[While at it, update the miscdev interface code start comment.]

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki 
Reviewed-by: Ulf Hansson 
Acked-by: Greg Kroah-Hartman 
Reviewed-by: Amit Kucheria 
Tested-by: Amit Kucheria

PM: QoS: Drop PM_QOS_CPU_DMA_LATENCY notifier chain

2020-02-13T10:26:27+00:00

Notice that pm_qos_remove_notifier() is not used at all and the only
caller of pm_qos_add_notifier() is the cpuidle core, which only needs
the PM_QOS_CPU_DMA_LATENCY notifier to invoke wake_up_all_idle_cpus()
upon changes of the PM_QOS_CPU_DMA_LATENCY target value.

First, to ensure that wake_up_all_idle_cpus() will be called
whenever the PM_QOS_CPU_DMA_LATENCY target value changes, modify the
pm_qos_add/update/remove_request() family of functions to check if
the effective constraint for the PM_QOS_CPU_DMA_LATENCY has changed
and call wake_up_all_idle_cpus() directly in that case.

Next, drop the PM_QOS_CPU_DMA_LATENCY notifier from cpuidle as it is
not necessary any more.

Finally, drop both pm_qos_add_notifier() and pm_qos_remove_notifier(),
as they have no callers now, along with cpu_dma_lat_notifier which is
only used by them.

Signed-off-by: Rafael J. Wysocki 
Reviewed-by: Ulf Hansson 
Reviewed-by: Amit Kucheria 
Tested-by: Amit Kucheria