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

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Message-ID: <CAJZ5v0h4-cSFs+ED3ymJKHKkEAproXCtB2t3cP1wcyd6eq=Sgg@mail.gmail.com>
Date: Tue, 10 Dec 2024 18:59:16 +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, 
	M.Chehab@...wei.com, roberto.sassu@...wei.com, shiju.jose@...wei.com, 
	prime.zeng@...ilicon.com, linuxarm@...wei.com
Subject: Re: [PATCH] acpi: Fix hed module initialization order when it is built-in

On Fri, Nov 15, 2024 at 4:56 AM Xiaofei Tan <tanxiaofei@...wei.com> wrote:
>
> When the module hed is built-in, the init order is determined by
> Makefile order.

Are you sure?

> 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.

Well, the problem is real, but does the change really prevent it from
happening or does it just increase the likelihood of success?

In the latter case, and generally speaking too, it would be better to
add explicit synchronization between evged and hed.

> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
> Signed-off-by: Xiaofei Tan <tanxiaofei@...wei.com>
> ---
>  drivers/acpi/Makefile | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
> index 61ca4afe83dc..54f60b7922ad 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
> +
>  #
>  # 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
> --
> 2.33.0
>