linux-kernel - Re: [RFC PATCH v2 3/4] acpi: apei: Do not panic() when correctable errors are marked as fatal.

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Date:   Thu, 19 Apr 2018 16:35:52 +0100
From:   James Morse <james.morse@....com>
To:     "Alex G." <mr.nuke.me@...il.com>
Cc:     Borislav Petkov <bp@...en8.de>, linux-acpi@...r.kernel.org,
        linux-edac@...r.kernel.org, rjw@...ysocki.net, lenb@...nel.org,
        tony.luck@...el.com, tbaicar@...eaurora.org, will.deacon@....com,
        shiju.jose@...wei.com, zjzhang@...eaurora.org,
        gengdongjiu@...wei.com, linux-kernel@...r.kernel.org,
        alex_gagniuc@...lteam.com, austin_bolen@...l.com,
        shyam_iyer@...l.com, devel@...ica.org, mchehab@...nel.org,
        robert.moore@...el.com, erik.schmauss@...el.com
Subject: Re: [RFC PATCH v2 3/4] acpi: apei: Do not panic() when correctable
 errors are marked as fatal.

Hi Alex,

(I haven't read through all this yet, just on this one:)

On 04/19/2018 03:57 PM, Alex G. wrote:
 > Maybe it's better move the AER handling to NMI/IRQ context, since
 > ghes_handle_aer() is only scheduling the real AER andler, and is irq
 > safe. I'm scratching my head about why we're messing with IRQ work from
 > NMI context, instead of just scheduling a regular handler to take care
 > of things.

We can't touch schedule_work_on() from NMI context as it takes spinlocks and
disables interrupts. (see __queue_work()) The NMI may have interrupted 
IRQ-context code
that was already holding the same locks.

IRQ-work behaves differently, it uses an llist for the work and an arch 
code hook
to raise a self-IPI.


Thanks,

James