linux-kernel - Re: [PATCH] acpi: apei: clear error status before acknowledging the error

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Message-ID: <01b3550d-1fca-c051-3581-41dda3b62779@codeaurora.org>
Date:   Mon, 31 Jul 2017 11:44:12 -0600
From:   "Baicar, Tyler" <tbaicar@...eaurora.org>
To:     "Luck, Tony" <tony.luck@...el.com>
Cc:     Borislav Petkov <bp@...e.de>, rjw@...ysocki.net, lenb@...nel.org,
        will.deacon@....com, james.morse@....com, shiju.jose@...wei.com,
        geliangtang@...il.com, andriy.shevchenko@...ux.intel.com,
        linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] acpi: apei: clear error status before acknowledging the
 error

On 7/31/2017 11:00 AM, Luck, Tony wrote:
> On Mon, Jul 31, 2017 at 10:15:27AM -0600, Baicar, Tyler wrote:
>> I think the better thing to do in this case is still send the ack. If
>> ghes_read_estatus() fails, then
>> either we are unable to read the estatus or the estatus is empty/invalid.
> Right now we silently handle that failure of ghes_read_estatus(). That
> might be hiding some Linux bugs if we are calling ghes_proc() in cases
> where we shouldn't.
>
> Perhaps we should have something like this, so if systems do start acting
> weirdly there will be a note that we took this path:
>
> 	rc = ghes_read_estatus(ghes, 0);
> 	if (rc) {
> 		pr_notice("surprise failure reading ghes estatus\n");
> 		goto out;
> 	}
Thank you Tony for the feedback, I can add a print like this in the next 
version. I'll verify that
rc is not -ENOENT though so we don't print it on empty scenarios since 
the polled source
will be hitting this path frequently.

-Tyler
>
>> If we do not send the ack, then we will be in a scenario where FW will not
>> send any more errors.
> We might ACK something that the firmware didn't send, which may
> lead to other problems.
>
>> I think it would be better to still have the FW send the errors and kernel
>> complain about issues with
> But I agree with this. We should send the ACK.  Luckliy this doesn't have
> a long legacy problem because the whole ACK mechanism is a new thing. So
> we only have to worry about GHESv2 supporting BIOS.
>
> -Tony

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