linux-kernel - Re: [PATCH V3 06/10] acpi: apei: panic OS with fatal error status block

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Date:   Thu, 13 Oct 2016 14:00:30 +0100
From:   Suzuki K Poulose <Suzuki.Poulose@....com>
To:     Tyler Baicar <tbaicar@...eaurora.org>, christoffer.dall@...aro.org,
        marc.zyngier@....com, pbonzini@...hat.com, rkrcmar@...hat.com,
        linux@...linux.org.uk, catalin.marinas@....com,
        will.deacon@....com, rjw@...ysocki.net, lenb@...nel.org,
        matt@...eblueprint.co.uk, robert.moore@...el.com,
        lv.zheng@...el.com, mark.rutland@....com, james.morse@....com,
        akpm@...ux-foundation.org, sandeepa.s.prabhu@...il.com,
        shijie.huang@....com, paul.gortmaker@...driver.com,
        tomasz.nowicki@...aro.org, fu.wei@...aro.org, rostedt@...dmis.org,
        bristot@...hat.com, linux-arm-kernel@...ts.infradead.org,
        kvmarm@...ts.cs.columbia.edu, Dkvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
        linux-efi@...r.kernel.org, devel@...ica.org
Cc:     "Jonathan (Zhixiong) Zhang" <zjzhang@...eaurora.org>
Subject: Re: [PATCH V3 06/10] acpi: apei: panic OS with fatal error status
 block

On 07/10/16 22:31, Tyler Baicar wrote:
> From: "Jonathan (Zhixiong) Zhang" <zjzhang@...eaurora.org>
>
> Even if an error status block's severity is fatal, the kernel does not
> honor the severity level and panic.
>
> With the firmware first model, the platform could inform the OS about a
> fatal hardware error through the non-NMI GHES notification type. The OS
> should panic when a hardware error record is received with this
> severity.
>
> Call panic() after CPER data in error status block is printed if
> severity is fatal, before each error section is handled.
>
> Signed-off-by: Jonathan (Zhixiong) Zhang <zjzhang@...eaurora.org>
> ---
>  drivers/acpi/apei/ghes.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
> index 28d5a09..36894c8 100644
> --- a/drivers/acpi/apei/ghes.c
> +++ b/drivers/acpi/apei/ghes.c
> @@ -141,6 +141,8 @@ static unsigned long ghes_estatus_pool_size_request;
>  static struct ghes_estatus_cache *ghes_estatus_caches[GHES_ESTATUS_CACHES_SIZE];
>  static atomic_t ghes_estatus_cache_alloced;
>
> +static int ghes_panic_timeout __read_mostly = 30;
> +
>  static int ghes_ioremap_init(void)
>  {
>  	ghes_ioremap_area = __get_vm_area(PAGE_SIZE * GHES_IOREMAP_PAGES,
> @@ -715,6 +717,12 @@ static int ghes_proc(struct ghes *ghes)
>  		if (ghes_print_estatus(NULL, ghes->generic, ghes->estatus))
>  			ghes_estatus_cache_add(ghes->generic, ghes->estatus);
>  	}
> +	if (ghes_severity(ghes->estatus->error_severity) >= GHES_SEV_PANIC) {
> +		if (panic_timeout == 0)
> +			panic_timeout = ghes_panic_timeout;
> +		panic("Fatal hardware error!");

I think there is a chance that we might miss the o/p of ghes_print_estatus() as we use
no pfx, and it could default to the normal loglevel and would never get printed
if panic() is encountered before it. On the other hand, there is already a
__ghes_panic() which does similar stuff. Is there a way we could reuse
(may be even parts of) it ? Or at least use KERN_EMERG for the ghes_print_estatus(),
if the severity could result in panic() ?

Cheers
Suzuki