user/sven/linux.git/include/linux/cpufreq.h, branch v5.4.76

cpufreq: Avoid creating excessively large stack frames

2020-02-11T12:35:25Z

commit 1e4f63aecb53e48468661e922fc2fa3b83e55722 upstream. In the process of modifying a cpufreq policy, the cpufreq core makes a copy of it including all of the internals which is stored on the CPU stack. Because struct cpufreq_policy is relatively large, this may cause the size of the stack frame to exceed the 2 KB limit and so the GCC complains when -Wframe-larger-than= is used. In fact, it is not necessary to copy the entire policy structure in order to modify it, however. First, because cpufreq_set_policy() obtains the min and max policy limits from frequency QoS now, it is not necessary to pass the limits to it from the callers. The only things that need to be passed to it from there are the new governor pointer or (if there is a built-in governor in the driver) the "policy" value representing the governor choice. They both can be passed as individual arguments, though, so make cpufreq_set_policy() take them this way and rework its callers accordingly. This avoids making copies of cpufreq policies in the callers of cpufreq_set_policy(). Second, cpufreq_set_policy() still needs to pass the new policy data to the ->verify() callback of the cpufreq driver whose task is to sanitize the min and max policy limits. It still does not need to make a full copy of struct cpufreq_policy for this purpose, but it needs to pass a few items from it to the driver in case they are needed (different drivers have different needs in that respect and all of them have to be covered). For this reason, introduce struct cpufreq_policy_data to hold copies of the members of struct cpufreq_policy used by the existing ->verify() driver callbacks and pass a pointer to a temporary structure of that type to ->verify() (instead of passing a pointer to full struct cpufreq_policy to it). While at it, notice that intel_pstate and longrun don't really need to verify the "policy" value in struct cpufreq_policy, so drop those check from them to avoid copying "policy" into struct cpufreq_policy_data (which allows it to be slightly smaller). Also while at it fix up white space in a couple of places and make cpufreq_set_policy() static (as it can be so). Fixes: 3000ce3c52f8 ("cpufreq: Use per-policy frequency QoS") Link: https://lore.kernel.org/linux-pm/CAMuHMdX6-jb1W8uC2_237m8ctCpsnGp=JCxqt8pCWVqNXHmkVg@mail.gmail.com Reported-by: kbuild test robot Reported-by: Geert Uytterhoeven Cc: 5.4+ # 5.4+ Signed-off-by: Rafael J. Wysocki Acked-by: Viresh Kumar Signed-off-by: Greg Kroah-Hartman

cpufreq: Avoid leaving stale IRQ work items during CPU offline

2019-12-31T15:46:06Z

commit 85572c2c4a45a541e880e087b5b17a48198b2416 upstream. The scheduler code calling cpufreq_update_util() may run during CPU offline on the target CPU after the IRQ work lists have been flushed for it, so the target CPU should be prevented from running code that may queue up an IRQ work item on it at that point. Unfortunately, that may not be the case if dvfs_possible_from_any_cpu is set for at least one cpufreq policy in the system, because that allows the CPU going offline to run the utilization update callback of the cpufreq governor on behalf of another (online) CPU in some cases. If that happens, the cpufreq governor callback may queue up an IRQ work on the CPU running it, which is going offline, and the IRQ work may not be flushed after that point. Moreover, that IRQ work cannot be flushed until the "offlining" CPU goes back online, so if any other CPU calls irq_work_sync() to wait for the completion of that IRQ work, it will have to wait until the "offlining" CPU is back online and that may not happen forever. In particular, a system-wide deadlock may occur during CPU online as a result of that. The failing scenario is as follows. CPU0 is the boot CPU, so it creates a cpufreq policy and becomes the "leader" of it (policy->cpu). It cannot go offline, because it is the boot CPU. Next, other CPUs join the cpufreq policy as they go online and they leave it when they go offline. The last CPU to go offline, say CPU3, may queue up an IRQ work while running the governor callback on behalf of CPU0 after leaving the cpufreq policy because of the dvfs_possible_from_any_cpu effect described above. Then, CPU0 is the only online CPU in the system and the stale IRQ work is still queued on CPU3. When, say, CPU1 goes back online, it will run irq_work_sync() to wait for that IRQ work to complete and so it will wait for CPU3 to go back online (which may never happen even in principle), but (worse yet) CPU0 is waiting for CPU1 at that point too and a system-wide deadlock occurs. To address this problem notice that CPUs which cannot run cpufreq utilization update code for themselves (for example, because they have left the cpufreq policies that they belonged to), should also be prevented from running that code on behalf of the other CPUs that belong to a cpufreq policy with dvfs_possible_from_any_cpu set and so in that case the cpufreq_update_util_data pointer of the CPU running the code must not be NULL as well as for the CPU which is the target of the cpufreq utilization update in progress. Accordingly, change cpufreq_this_cpu_can_update() into a regular function in kernel/sched/cpufreq.c (instead of a static inline in a header file) and make it check the cpufreq_update_util_data pointer of the local CPU if dvfs_possible_from_any_cpu is set for the target cpufreq policy. Also update the schedutil governor to do the cpufreq_this_cpu_can_update() check in the non-fast-switch case too to avoid the stale IRQ work issues. Fixes: 99d14d0e16fa ("cpufreq: Process remote callbacks from any CPU if the platform permits") Link: https://lore.kernel.org/linux-pm/20191121093557.bycvdo4xyinbc5cb@vireshk-i7/ Reported-by: Anson Huang Tested-by: Anson Huang Cc: 4.14+ # 4.14+ Signed-off-by: Rafael J. Wysocki Acked-by: Viresh Kumar Tested-by: Peng Fan (i.MX8QXP-MEK) Signed-off-by: Rafael J. Wysocki Signed-off-by: Greg Kroah-Hartman

cpufreq: Use per-policy frequency QoS

2019-10-21T00:05:21Z

Replace the CPU device PM QoS used for the management of min and max frequency constraints in cpufreq (and its users) with per-policy frequency QoS to avoid problems with cpufreq policies covering more then one CPU. Namely, a cpufreq driver is registered with the subsys interface which calls cpufreq_add_dev() for each CPU, starting from CPU0, so currently the PM QoS notifiers are added to the first CPU in the policy (i.e. CPU0 in the majority of cases). In turn, when the cpufreq driver is unregistered, the subsys interface doing that calls cpufreq_remove_dev() for each CPU, starting from CPU0, and the PM QoS notifiers are only removed when cpufreq_remove_dev() is called for the last CPU in the policy, say CPUx, which as a rule is not CPU0 if the policy covers more than one CPU. Then, the PM QoS notifiers cannot be removed, because CPUx does not have them, and they are still there in the device PM QoS notifiers list of CPU0, which prevents new PM QoS notifiers from being registered for CPU0 on the next attempt to register the cpufreq driver. The same issue occurs when the first CPU in the policy goes offline before unregistering the driver. After this change it does not matter which CPU is the policy CPU at the driver registration time and whether or not it is online all the time, because the frequency QoS is per policy and not per CPU. Fixes: 67d874c3b2c6 ("cpufreq: Register notifiers with the PM QoS framework") Reported-by: Dmitry Osipenko Tested-by: Dmitry Osipenko Reported-by: Sudeep Holla Tested-by: Sudeep Holla Diagnosed-by: Viresh Kumar Link: https://lore.kernel.org/linux-pm/5ad2624194baa2f53acc1f1e627eb7684c577a19.1562210705.git.viresh.kumar@linaro.org/T/#md2d89e95906b8c91c15f582146173dce2e86e99f Link: https://lore.kernel.org/linux-pm/20191017094612.6tbkwoq4harsjcqv@vireshk-i7/T/#m30d48cc23b9a80467fbaa16e30f90b3828a5a29b Signed-off-by: Rafael J. Wysocki Acked-by: Viresh Kumar

cpufreq: Remove CPUFREQ_ADJUST and CPUFREQ_NOTIFY policy notifier events

2019-09-02T20:44:04Z

No driver makes reference to these events now, remove them and the code related to them. Signed-off-by: Viresh Kumar Signed-off-by: Rafael J. Wysocki

cpufreq: Add policy create/remove notifiers back

2019-08-10T12:05:48Z

This effectively reverts some changes made by commit f9f41e3ef99 ("cpufreq: Remove policy create/remove notifiers"). We have a new use case for policy create/remove notifiers (for allocating/freeing QoS requests per policy), so add them back. Signed-off-by: Viresh Kumar [ rjw: Subject & changelog ] Signed-off-by: Rafael J. Wysocki

Merge branch 'pm-cpufreq'

2019-07-18T07:49:30Z

* pm-cpufreq: cpufreq: Make cpufreq_generic_init() return void cpufreq: imx-cpufreq-dt: Add i.MX8MN support cpufreq: Add QoS requests for userspace constraints cpufreq: intel_pstate: Reuse refresh_frequency_limits() cpufreq: Register notifiers with the PM QoS framework PM / QoS: Add support for MIN/MAX frequency constraints PM / QOS: Pass request type to dev_pm_qos_read_value() PM / QOS: Rename __dev_pm_qos_read_value() and dev_pm_qos_raw_read_value() PM / QOS: Pass request type to dev_pm_qos_{add|remove}_notifier()

cpufreq: Make cpufreq_generic_init() return void

2019-07-16T08:20:11Z

It always returns 0 (success) and its return type should really be void. Over that, many drivers have added error handling code based on its return value, which is not required at all. Change its return type to void and update all the callers. Signed-off-by: Viresh Kumar Signed-off-by: Rafael J. Wysocki

cpufreq: Add QoS requests for userspace constraints

2019-07-08T21:56:39Z

This implements QoS requests to manage userspace configuration of min and max frequency. Reviewed-by: Matthias Kaehlcke Reviewed-by: Ulf Hansson Signed-off-by: Viresh Kumar Tested-by: syzbot Signed-off-by: Rafael J. Wysocki

cpufreq: intel_pstate: Reuse refresh_frequency_limits()

2019-07-08T21:56:39Z

The implementation of intel_pstate_update_max_freq() is quite similar to refresh_frequency_limits(), lets reuse it. Finding minimum of policy->user_policy.max and policy->cpuinfo.max_freq in intel_pstate_update_max_freq() is redundant as cpufreq_set_policy() will call the ->verify() callback of intel-pstate driver, which will do this comparison anyway and so dropping it from intel_pstate_update_max_freq() doesn't harm. Signed-off-by: Viresh Kumar Signed-off-by: Rafael J. Wysocki

cpufreq: Register notifiers with the PM QoS framework

2019-07-08T21:56:13Z

Register notifiers for min/max frequency constraints with the PM QoS framework. The constraints are also taken into consideration in cpufreq_set_policy(). This also relocates cpufreq_policy_put_kobj() as it is required to be called from cpufreq_policy_alloc() now. refresh_frequency_limits() is updated to avoid calling cpufreq_set_policy() for inactive policies and handle_update() is updated to have proper locking in place. No constraints are added until now though. Reviewed-by: Matthias Kaehlcke Reviewed-by: Ulf Hansson Signed-off-by: Viresh Kumar Tested-by: Pavel Machek Signed-off-by: Rafael J. Wysocki