kernel/linux.git/drivers/acpi/processor_idle.c, branch v6.18.48

ACPI: processor_idle: Mark LPI enter functions as __cpuidle

2026-07-24T14:16:39+00:00

[ Upstream commit 956ca5d72c76504824c8eb601879da9476973e15 ] When function tracing or Kprobes is enabled, entering an ACPI Low Power Idle (LPI) state triggers the following RCU splat: RCU not on for: acpi_idle_lpi_enter+0x4/0xd8 WARNING: CPU: 8 PID: 0 at include/linux/trace_recursion.h:162 function_trace_call+0x1e8/0x228 The acpi_idle_lpi_enter() function is invoked within the cpuidle path after RCU has already been disabled for the current local CPU. Consequently, ftrace's function_trace_call() expects RCU to be actively watching before recording trace data, emitting a warning if it is not. Fix this by annotating acpi_idle_lpi_enter(), the generic __weak stub, and the RISC-V implementation of acpi_processor_ffh_lpi_enter() with __cpuidle. This moves these functions into the '.cpuidle.text' section, implicitly disabling ftrace instrumentation (notrace) along this sensitive path and preventing trace-induced RCU warnings during idle entry. Fixes: a36a7fecfe60 ("ACPI / processor_idle: Add support for Low Power Idle(LPI) states") Signed-off-by: Li RongQing Acked-by: lihuisong@huawei.com Link: https://patch.msgid.link/20260616072617.2272-1-lirongqing@baidu.com Signed-off-by: Rafael J. Wysocki Signed-off-by: Sasha Levin

Revert "ACPI: processor: idle: Optimize ACPI idle driver registration"

2025-11-25T15:08:06+00:00

Revert commit 7a8c994cbb2d ("ACPI: processor: idle: Optimize ACPI idle driver registration") because it is reported to introduce a cpuidle regression leading to a kernel crash on a platform using the ACPI idle driver. Signed-off-by: Rafael J. Wysocki Reported-by: Borislav Petkov Tested-by: Borislav Petkov (AMD) Closes: https://lore.kernel.org/lkml/20251124200019.GIaSS5U9HhsWBotrQZ@fat_crate.local/

Revert "ACPI: processor: idle: Redefine two functions as void"

2025-11-25T13:53:33+00:00

Revert commit fbd401e95e56 ("ACPI: processor: idle: Redefine two functions as void") because it depends on a problematic one. Signed-off-by: Rafael J. Wysocki

Revert "ACPI: processor: Do not expose global variable acpi_idle_driver"

2025-11-25T13:50:25+00:00

Revert commit 559f2eacc8a2 ACPI: processor: Do not expose global variable acpi_idle_driver" because it depends on a problematic one. Signed-off-by: Rafael J. Wysocki

ACPI: processor: Do not expose global variable acpi_idle_driver

2025-09-23T13:33:19+00:00

Move the cpuidle driver check from __acpi_processor_start() to acpi_processor_power_init() which allows variable acpi_idle_driver to become static. No intentional functional impact. Signed-off-by: Huisong Li Link: https://patch.msgid.link/20250923032428.2656329-2-lihuisong@huawei.com [ rjw: Subject tweak, new changelog, adjustment of a new comment ] Signed-off-by: Rafael J. Wysocki

ACPI: processor: idle: Redefine two functions as void

2025-09-19T20:49:49+00:00

Notice that acpi_processor_power_init() and acpi_processor_power_exit() don't need to return any values because their callers don't check them anyway, so redefine those functions as void. While at it, rearrange the code in acpi_processor_power_init() to reduce the indentation level, get rid of a redundant local variable in that function, and rephrase a code comment in it. No intentional functional impact. Signed-off-by: Rafael J. Wysocki Reviewed-by: Mario Limonciello (AMD)

ACPI: processor: idle: Eliminate static variable flat_state_cnt

2025-09-02T14:08:53+00:00

Instead of using static variable flat_state_cnt to pass data between functions involved in the _LPI information processing, pass the current number of "flattened" idle states to flatten_lpi_states() and make it return the updated number of those states. At the same time, use a local variable called state_count to store the number of "flattened" idle states found so far in acpi_processor_get_lpi_info(). No intentional functional impact. Signed-off-by: Rafael J. Wysocki Reviewed-by: Sudeep Holla Tested-by: Sudeep Holla Acked-by: lihuisong@huawei.com Link: https://patch.msgid.link/10715991.nUPlyArG6x@rafael.j.wysocki

ACPI: processor: idle: Add module import namespace

2025-09-02T14:08:53+00:00

Add a new module import namespace called ACPI_PROCESSOR_IDLE for functions exported from the non-modular part of the ACPI processor driver to the modular part of it. Export acpi_processor_claim_cst_control() and acpi_processor_evaluate_cst() in that namespace to hide them from unrelated modules. They are also used by the intel_idle driver, but it is non-modular, so it can call them regardless of the way the symbols are exported. Signed-off-by: Rafael J. Wysocki Link: https://patch.msgid.link/3376499.aeNJFYEL58@rafael.j.wysocki

ACPI: processor: idle: Optimize ACPI idle driver registration

2025-09-02T14:08:25+00:00

Currently, the ACPI idle driver is registered from within a CPU hotplug callback. Although this didn't cause any functional issues, this is questionable and confusing. And it is better to register the cpuidle driver when all of the CPUs have been brought up. So add a new function to initialize acpi_idle_driver based on the power management information of an available CPU and register cpuidle driver in acpi_processor_driver_init(). Signed-off-by: Huisong Li Link: https://patch.msgid.link/20250728070612.1260859-3-lihuisong@huawei.com [ rjw: Added missing inline modifiers ] Signed-off-by: Rafael J. Wysocki

ACPI: processor: idle: Fix memory leak when register cpuidle device failed

2025-08-22T19:26:26+00:00

The cpuidle device's memory is leaked when cpuidle device registration fails in acpi_processor_power_init(). Free it as appropriate. Fixes: 3d339dcbb56d ("cpuidle / ACPI : move cpuidle_device field out of the acpi_processor_power structure") Signed-off-by: Huisong Li Link: https://patch.msgid.link/20250728070612.1260859-2-lihuisong@huawei.com [ rjw: Changed the order of the new statements, added empty line after if () ] [ rjw: Changelog edits ] Signed-off-by: Rafael J. Wysocki