linux-kernel - Re: [PATCH v2] acpi: Fix HED module initialization order when it is built-in

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Message-ID: <CAJZ5v0gWPkmvpPGMO5fbXfrOcAgofML+WQE54cwiwDbaK6vfZw@mail.gmail.com>
Date: Wed, 15 Jan 2025 16:51:39 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Xiaofei Tan <tanxiaofei@...wei.com>
Cc: rafael@...nel.org, lenb@...nel.org, linux-acpi@...r.kernel.org, 
	linux-kernel@...r.kernel.org, jonathan.cameron@...wei.com, 
	mchehab+huawei@...nel.org, roberto.sassu@...wei.com, shiju.jose@...wei.com, 
	prime.zeng@...ilicon.com, linuxarm@...wei.com
Subject: Re: [PATCH v2] acpi: Fix HED module initialization order when it is built-in

On Wed, Jan 15, 2025 at 1:38 PM Xiaofei Tan <tanxiaofei@...wei.com> wrote:
>
> When the module HED is built-in, the init order is determined by
> Makefile order. That order violates expectations. Because the module
> HED init is behind evged. RAS records can't be handled in the
> special time window that evged has initialized while HED not.
> If the number of such RAS records is more than the APEI HEST error
> source number, the HEST resources could be occupied all, and then
> could affect subsequent RAS error reporting.
>
> If build HED as a module, the problem remains. To solve this problem
> completely, change the ACPI_HED from tristate to bool.
>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
> Signed-off-by: Xiaofei Tan <tanxiaofei@...wei.com>
> ---
>  drivers/acpi/Kconfig  | 2 +-
>  drivers/acpi/Makefile | 8 +++++++-
>  2 files changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
> index d81b55f5068c..7f10aa38269d 100644
> --- a/drivers/acpi/Kconfig
> +++ b/drivers/acpi/Kconfig
> @@ -452,7 +452,7 @@ config ACPI_SBS
>           the modules will be called sbs and sbshc.
>
>  config ACPI_HED
> -       tristate "Hardware Error Device"
> +       bool "Hardware Error Device"
>         help
>           This driver supports the Hardware Error Device (PNP0C33),
>           which is used to report some hardware errors notified via
> diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
> index 40208a0f5dfb..b50d1baeb71f 100644
> --- a/drivers/acpi/Makefile
> +++ b/drivers/acpi/Makefile
> @@ -15,6 +15,13 @@ endif
>
>  obj-$(CONFIG_ACPI)             += tables.o
>
> +#
> +# The hed.o needs to be in front of evged.o to avoid the problem that
> +# RAS errors cannot be handled in the special time window of startup
> +# phase that evged has initialized while hed not.
> +#
> +obj-$(CONFIG_ACPI_HED)         += hed.o
> +

I'm not sure why you are insisting on this Makefile ordering change.

It would be much more robust to run the hed driver init at a different
initcall level than evged.

If there is a problem with this approach, it needs to be mentioned in
the changelog or in the comment above.

>  #
>  # ACPI Core Subsystem (Interpreter)
>  #
> @@ -95,7 +102,6 @@ obj-$(CONFIG_ACPI_HOTPLUG_IOAPIC) += ioapic.o
>  obj-$(CONFIG_ACPI_BATTERY)     += battery.o
>  obj-$(CONFIG_ACPI_SBS)         += sbshc.o
>  obj-$(CONFIG_ACPI_SBS)         += sbs.o
> -obj-$(CONFIG_ACPI_HED)         += hed.o
>  obj-$(CONFIG_ACPI_EC_DEBUGFS)  += ec_sys.o
>  obj-$(CONFIG_ACPI_BGRT)                += bgrt.o
>  obj-$(CONFIG_ACPI_CPPC_LIB)    += cppc_acpi.o
> --