linux-kernel - Re: [RFC PATCH v4 3/3] acpi: apei: Do not panic() on PCIe errors reported through GHES

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Message-ID: <20180511160253.GF12705@pd.tnic>
Date:   Fri, 11 May 2018 18:02:53 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     "Alex G." <mr.nuke.me@...il.com>
Cc:     alex_gagniuc@...lteam.com, austin_bolen@...l.com,
        shyam_iyer@...l.com, "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>, Tony Luck <tony.luck@...el.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Robert Moore <robert.moore@...el.com>,
        Erik Schmauss <erik.schmauss@...el.com>,
        Tyler Baicar <tbaicar@...eaurora.org>,
        Will Deacon <will.deacon@....com>,
        James Morse <james.morse@....com>,
        Shiju Jose <shiju.jose@...wei.com>,
        "Jonathan (Zhixiong) Zhang" <zjzhang@...eaurora.org>,
        Dongjiu Geng <gengdongjiu@...wei.com>,
        linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-edac@...r.kernel.org, devel@...ica.org
Subject: Re: [RFC PATCH v4 3/3] acpi: apei: Do not panic() on PCIe errors
 reported through GHES

On Fri, May 11, 2018 at 10:54:09AM -0500, Alex G. wrote:
> That being clarified, should I replace "crackmonkey" with "broken" in
> the commit message?

Keep your opinion *outside* of commit messages - their goal is to
explain *why* the change is being made in strictly technical language so
that when someone looks at git history, someone can know *why*.

> Borislav, I sense some confusion. AER is not a "reporting" driver. It
> handles the errors. You can't leave these errors unhandled. They
> propagate to the root complex and can cause fatal MCEs when not handled.
> The window to handle the error is pretty large, so it's not a concern
> when you're handling it.

I think *you* didn't get it: IS_ENABLED(CONFIG_ACPI_APEI_PCIEAER) is not
enough of a check to confirm that there actually *is* an AER driver to
handle the errors. If you really want to make sure the driver is loaded
and functioning, then you need an explicit registering mechanism or some
other way of checking it really is there and handling errors.

-- 
Regards/Gruss,
    Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.