user/sven/linux.git/kernel/power/qos.c, branch v5.7.4

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

2020-03-03T22:34:51Z

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

2020-02-14T09:37:27Z

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

2020-02-14T09:37:26Z

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along with copyright and authors information to them and changing the qos.c description to better reflect its contents (outdated information is dropped from it in particular).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

2020-02-14T09:37:26Z

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

2020-02-13T10:26:46Z

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

2020-02-13T10:26:39Z

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

2020-02-13T10:26:33Z

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

2020-02-13T10:26:27Z

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

PM: QoS: Redefine struct pm_qos_request and drop struct pm_qos_object

2020-02-13T10:26:19Z

First, change the definition of struct pm_qos_request so that it contains a struct pm_qos_constraints pointer (called "qos") instead of a PM QoS class number (in preparation for dropping the PM QoS classes concept altogether going forward) and move its definition (along with the definition of struct pm_qos_flags_request that does not change) after the definition of struct pm_qos_constraints. Next, drop the definition of struct pm_qos_object and the null_pm_qos and cpu_dma_pm_qos variables of that type along with pm_qos_array[] holding pointers to them and change the code to refer to the pm_qos_constraints structure directly or to use the new qos pointer in struct pm_qos_request for that instead of going through pm_qos_array[] to access it. Also update kerneldoc comments that mention pm_qos_class to refer to PM_QOS_CPU_DMA_LATENCY directly instead. Finally, drop register_pm_qos_misc(), introduce cpu_latency_qos_miscdev (with the name field set to "cpu_dma_latency") to implement the CPU latency QoS interface in /dev/ and register it directly from pm_qos_power_init(). After these changes the notion of PM QoS classes remains only in the API (in the form of redundant function parameters that are ignored) and in the definitions of PM QoS trace events. While at it, some redundant local variables are dropped etc. No intentional functional impact. Signed-off-by: Rafael J. Wysocki Reviewed-by: Ulf Hansson Reviewed-by: Amit Kucheria Tested-by: Amit Kucheria

PM: QoS: Clean up misc device file operations

2020-02-13T10:26:13Z

Reorder the code to avoid using extra function header declarations for the pm_qos_power_*() family of functions and drop those declarations. Also clean up the internals of those functions to consolidate checks, avoid using redundant local variables and similar. No intentional functional impact. Signed-off-by: Rafael J. Wysocki Reviewed-by: Ulf Hansson Reviewed-by: Amit Kucheria Tested-by: Amit Kucheria