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Subject: Re: [RFC PATCH v2 3/4] acpi: apei: Do not panic() when correctable
 errors are marked as fatal.
To:     "Alex G." <mr.nuke.me@gmail.com>
Cc:     Borislav Petkov <bp@alien8.de>, linux-acpi@vger.kernel.org,
        linux-edac@vger.kernel.org, rjw@rjwysocki.net, lenb@kernel.org,
        tony.luck@intel.com, tbaicar@codeaurora.org, will.deacon@arm.com,
        shiju.jose@huawei.com, zjzhang@codeaurora.org,
        gengdongjiu@huawei.com, linux-kernel@vger.kernel.org,
        alex_gagniuc@dellteam.com, austin_bolen@dell.com,
        shyam_iyer@dell.com, devel@acpica.org, mchehab@kernel.org,
        robert.moore@intel.com, erik.schmauss@intel.com
References: <20180416215903.7318-1-mr.nuke.me@gmail.com>
 <20180416215903.7318-4-mr.nuke.me@gmail.com> <20180418175415.GJ4795@pd.tnic>
 <bdc1d19b-3cc1-3f90-d276-414aaacdbd3a@gmail.com>
From:   James Morse <james.morse@arm.com>
Message-ID: <e5e107e7-e18e-725a-8f9b-95e6f033ab45@arm.com>
Date:   Thu, 19 Apr 2018 16:35:52 +0100
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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