Re: [外部邮件] Re: [PATCH][v2] ACPI: processor_idle: Mark LPI enter functions as __cpuidle

[Rafael J. Wysocki]

On Wed, Jun 24, 2026 at 3:51 AM Li,Rongqing <lirongqing@xxxxxxxxx> wrote:
>
> > > 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 <lirongqing@xxxxxxxxx>
> > > ---
> > > Diff with v1: add __cpuidle to acpi_processor_ffh_lpi_enter
> > >
> > >  drivers/acpi/processor_idle.c | 4 ++--  drivers/acpi/riscv/cpuidle.c
> > > | 2 +-
> > >  2 files changed, 3 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/acpi/processor_idle.c
> > > b/drivers/acpi/processor_idle.c index 390ab5f..4482cf2 100644
> > > --- a/drivers/acpi/processor_idle.c
> > > +++ b/drivers/acpi/processor_idle.c
> > > @@ -1143,7 +1143,7 @@ static int acpi_processor_get_lpi_info(struct
> > acpi_processor *pr)
> > >         return 0;
> > >  }
> > >
> > > -int __weak acpi_processor_ffh_lpi_enter(struct acpi_lpi_state *lpi)
> > > +int __weak __cpuidle acpi_processor_ffh_lpi_enter(struct
> > > +acpi_lpi_state *lpi)
> > >  {
> > >         return -ENODEV;
> > >  }
> > > @@ -1156,7 +1156,7 @@ int __weak acpi_processor_ffh_lpi_enter(struct
> > acpi_lpi_state *lpi)
> > >   *
> > >   * Return: 0 for success or negative value for error
> > >   */
> > > -static int acpi_idle_lpi_enter(struct cpuidle_device *dev,
> > > +static int __cpuidle acpi_idle_lpi_enter(struct cpuidle_device *dev,
> > >                                struct cpuidle_driver *drv, int index)
> > > {
> > >         struct acpi_processor *pr;
> > > diff --git a/drivers/acpi/riscv/cpuidle.c
> > > b/drivers/acpi/riscv/cpuidle.c index 624f9bb..c76dbab 100644
> > > --- a/drivers/acpi/riscv/cpuidle.c
> > > +++ b/drivers/acpi/riscv/cpuidle.c
> > > @@ -66,7 +66,7 @@ int acpi_processor_ffh_lpi_probe(unsigned int cpu)
> > >         return acpi_cpu_init_idle(cpu);  }
> > >
> > > -int acpi_processor_ffh_lpi_enter(struct acpi_lpi_state *lpi)
> > > +int __cpuidle acpi_processor_ffh_lpi_enter(struct acpi_lpi_state
> > > +*lpi)
> > >  {
> > >         u32 state = lpi->address;
> > >
> > > --
> >
> > Sashiko says that this change may not be sufficient to fully address the issue
> >
> > https://sashiko.dev/#/patchset/20260616072617.2272-1-lirongqing%40baidu
> > .com
> >
> > and that appears to be a valid concern.
>
> Should this fix be placed in a separate patch? CPU_PM_CPU_IDLE_ENTER_PARAM
> is also invoked by sbi_cpuidle_enter_state, which is itself already annotated with __cpuidle,
> so this appears to be a pre-existing issue in the RISC-V tree. It would be more appropriate
> to have RISC-V experts to fix it independently.

OK, fair enough.

Applied as 7.2-rc material, thanks!