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

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Message-ID: <dfa67fab-e9c1-baec-dd86-6c6ba79eabeb@huawei.com>
Date: Mon, 23 Dec 2024 17:31:08 +0800
From: Xiaofei Tan <tanxiaofei@...wei.com>
To: "Rafael J. Wysocki" <rafael@...nel.org>
CC: <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>,
	<mchehab+huawei@...nel.org>
Subject: Re: [PATCH] acpi: Fix hed module initialization order when it is
 built-in

Hi Rafael,

在 2024/12/11 1:59, Rafael J. Wysocki 写道:
> 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?

yes

>> 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?

It can be completely solved if the driver used as built-in way. If build HED as a
module, it not solved.

>
> 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
>>
> .