kernel/linux.git/drivers/acpi/processor_idle.c, branch v7.1-rc5

ACPI: processor: idle: Reset cpuidle on C-state list changes

2026-04-07T13:32:20+00:00

When a power notification event occurs, existing ACPI idle states may become obsolete. The current implementation only performs a partial update, leaving critical cpuidle parameters, like target_residency_ns and exit_latency_ns, stale. Furthermore, per-CPU cpuidle_device data, including last_residency_ns, states_usage, and the disable flag, are not properly synchronized. Using these stale values leads to incorrect power management decisions. To ensure all parameters are correctly synchronized, modify the notification handling logic: 1. Unregister all cpuidle_device instances to ensure a clean slate. 2. Unregister and re-register the ACPI idle driver. This forces the framework to re-evaluate global state parameters and ensures the driver state matches the new hardware power profile. 3. Re-initialize power information and re-register cpuidle_device for all possible CPUs to restore functional idle management. This complete reset ensures that the cpuidle framework and the underlying ACPI states are perfectly synchronized after a power state change. Signed-off-by: Huisong Li [ rjw: Subject rewrite ] Link: https://patch.msgid.link/20260407081141.2493581-3-lihuisong@huawei.com Signed-off-by: Rafael J. Wysocki

ACPI: processor: idle: Fix NULL pointer dereference in hotplug path

2026-04-04T18:42:37+00:00

A cpuidle_device might fail to register during boot, but the system can continue to run. In such cases, acpi_processor_hotplug() can trigger a NULL pointer dereference when accessing the per-cpu acpi_cpuidle_device. So add NULL pointer check for the per-cpu acpi_cpuidle_device in acpi_processor_hotplug. Signed-off-by: Huisong Li Link: https://patch.msgid.link/20260403090253.998322-1-lihuisong@huawei.com Signed-off-by: Rafael J. Wysocki

ACPI: processor: idle: Reset power_setup_done flag on initialization failure

2026-04-04T18:41:01+00:00

The 'power_setup_done' flag is a key indicator used across the ACPI processor driver to determine if cpuidle are properly configured and available for a given CPU. Currently, this flag is set during the early stages of initialization. However, if the subsequent registration of the cpuidle driver in acpi_processor_register_idle_driver() or the per-CPU device registration in acpi_processor_power_init() fails, this flag remains set. This may lead to some issues where other functions in ACPI idle driver use these flags. Fix this by explicitly resetting this flag to 0 in these error paths. Signed-off-by: Huisong Li Link: https://patch.msgid.link/20260403085343.866440-1-lihuisong@huawei.com Signed-off-by: Rafael J. Wysocki

ACPI: processor: idle: Replace strlcat() with better alternative

2026-03-18T19:55:39+00:00

strlcpy() and strlcat() are confusing APIs and the former one already gone from the kernel. In preparation to kill strlcat() replace it with the better alternative. Signed-off-by: Andy Shevchenko Link: https://patch.msgid.link/20260317080218.1814693-1-andriy.shevchenko@linux.intel.com Signed-off-by: Rafael J. Wysocki

ACPI: processor: idle: Remove redundant static variable and rename cstate check function

2026-03-11T18:26:28+00:00

The function acpi_processor_cstate_first_run_checks() is currently called only once during initialization in acpi_processor_register_idle_driver(). Since its execution is already limited by the caller's lifecycle, the internal static 'first_run' variable is redundant and can be safely removed. Additionally, the current function name is no longer descriptive of its behavior, so rename the function to acpi_processor_update_max_cstate() to better reflect its actual purpose. Signed-off-by: Huisong Li Link: https://patch.msgid.link/20260311065038.4151558-4-lihuisong@huawei.com [ rjw: Changelog edits ] Signed-off-by: Rafael J. Wysocki

ACPI: processor: idle: Move max_cstate update out of the loop

2026-03-11T18:26:13+00:00

The acpi_processor_cstate_first_run_checks() function, which updates max_cstate on certain platforms, only needs to be executed once. Move this call outside of the loop to avoid redundant executions. Signed-off-by: Huisong Li Link: https://patch.msgid.link/20260311065038.4151558-3-lihuisong@huawei.com Signed-off-by: Rafael J. Wysocki

ACPI: processor: idle: Remove redundant cstate check in acpi_processor_power_init

2026-03-11T18:25:14+00:00

The function acpi_processor_cstate_first_run_checks() is responsible for updating max_cstate and performing initial hardware validation. Currently, this function is invoked within acpi_processor_power_init(). However, the initialization flow already ensures this is called during acpi_processor_register_idle_driver(). Therefore, the call in acpi_processor_power_init() is redundant and effectively performs no work, so remove it. Signed-off-by: Huisong Li Link: https://patch.msgid.link/20260311065038.4151558-2-lihuisong@huawei.com [ rjw: Changelog edits ] Signed-off-by: Rafael J. Wysocki

ACPI: processor: idle: Add missing bounds check in flatten_lpi_states()

2026-03-09T18:52:00+00:00

The inner loop in flatten_lpi_states() that combines composite LPI states can increment flat_state_cnt multiple times within the loop. The condition that guards this (checks bounds against ACPI_PROCESSOR _MAX_POWER) occurs at the top of the outer loop. flat_state_cnt might exceed ACPI_PROCESSOR_MAX_POWER if it is incremented multiple times within the inner loop between outer loop iterations. Add a bounds check after the increment inside the inner loop so that it breaks out when flat_state_cnt reaches ACPI_PROCESSOR_MAX_POWER. The existing check in the outer loop will then handle the warning. Signed-off-by: Jingkai Tan Reviewed-by: Sudeep Holla Link: https://patch.msgid.link/20260305213831.53985-1-contact@jingk.ai Signed-off-by: Rafael J. Wysocki

Convert 'alloc_obj' family to use the new default GFP_KERNEL argument

2026-02-22T01:09:51+00:00

This was done entirely with mindless brute force, using git grep -l '\

treewide: Replace kmalloc with kmalloc_obj for non-scalar types

2026-02-21T09:02:28+00:00

This is the result of running the Coccinelle script from scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to avoid scalar types (which need careful case-by-case checking), and instead replace kmalloc-family calls that allocate struct or union object instances: Single allocations: kmalloc(sizeof(TYPE), ...) are replaced with: kmalloc_obj(TYPE, ...) Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...) are replaced with: kmalloc_objs(TYPE, COUNT, ...) Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...) are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...) (where TYPE may also be *VAR) The resulting allocations no longer return "void *", instead returning "TYPE *". Signed-off-by: Kees Cook