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 16:00:17 -0600
From:   Al Stone <ahs3@...hat.com>
To:     Tyler Baicar <tbaicar@...eaurora.org>, 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 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"?

> 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);
> 


-- 
ciao,
al
-----------------------------------
Al Stone
Software Engineer
Red Hat, Inc.
ahs3@...hat.com
-----------------------------------