linux-kernel - Re: [PATCH] acpi: apei: check for pending errors when probing HED type GHES entries

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Date:   Tue, 28 Mar 2017 16:02:34 -0600
From:   "Baicar, Tyler" <tbaicar@...eaurora.org>
To:     ahs3@...hat.com, rjw@...ysocki.net, lenb@...nel.org, bp@...e.de,
        prarit@...hat.com, bhelgaas@...gle.com, punit.agrawal@....com,
        mingo@...nel.org, linux-acpi@...r.kernel.org,
        linux-kernel@...r.kernel.org, shiju.jose@...wei.com,
        James.Morse@....com
Subject: Re: [PATCH] acpi: apei: check for pending errors when probing HED
 type GHES entries

On 3/28/2017 4:00 PM, Al Stone wrote:
> On 03/28/2017 02:14 PM, Tyler Baicar wrote:
>> If a HED type error occurs prior to GHES probing, the kernel will
>> never report the error. The HED driver will see that no notifiers
>> are registers, and clear the interrupt.
> ..."registers" or "registered"?
Oops :) I'll fix that to say registered.

Thanks,
Tyler
>
>> This becomes a more serious problem with firmware that supports
>> GHESv2 acknowledgements from the kernel. The firmware will populate
>> the error and wait for the kernel ack. But since the kernel will
>> never process the error we get into a state that the firmware will
>> not send any more errors and the kernel will never see or ack the
>> original error.
>>
>> Check for pending errors when probing HED type GHES entries to
>> avoid the above situation.
>>
>> This patch is based on Shiju's patch that adds support for GSIV
>> and GPIO notification types:
>> https://patchwork.kernel.org/patch/9628817/
>>
>> Signed-off-by: Tyler Baicar <tbaicar@...eaurora.org>
>> ---
>>   drivers/acpi/apei/ghes.c | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
>> index fd39929..cf5e938 100644
>> --- a/drivers/acpi/apei/ghes.c
>> +++ b/drivers/acpi/apei/ghes.c
>> @@ -1035,6 +1035,7 @@ static int ghes_probe(struct platform_device *ghes_dev)
>>   			register_acpi_hed_notifier(&ghes_notifier_hed);
>>   		list_add_rcu(&ghes->list, &ghes_hed);
>>   		mutex_unlock(&ghes_list_mutex);
>> +		ghes_proc(ghes);
>>   		break;
>>   	case ACPI_HEST_NOTIFY_NMI:
>>   		ghes_nmi_add(ghes);
>>
>

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