Re: [RFC][RFT][PATCH] ACPI: Protection from suspending in the middle of EC transaction

From: Alan Jenkins
Date: Sun Jan 31 2010 - 09:11:34 EST

On 1/30/10, Rafael J. Wysocki <rjw@xxxxxxx> wrote:
> Hi,
> While Maxim is testing if the patch below helps with
> I think it's necessary anyway.
> The problem is that currently there's nothing to prevent us from suspending
> in
> the middle of an EC transaction in progress, at least as far as I can see.
> As a result, we can suspend with the ACPI global lock held or something like
> this, which leads to problems especially for hibernation (if the resume
> kernel
> passes control to the image kernel in the middle of an EC transaction,
> things
> aren't nice). For this reason I think we should wait until there are no EC
> transactions in progress before we suspend and we should prevent any new
> EC transactions from starting after that point. The patch below does that.

I also believe this is a problem. I reported the following -

<> "Pressing acpi
hotkeys duing hibernation may occasionally cause EC transaction

and posted a patch, but I couldn't reproduce my specific issue in
order to confirm that the patch helped.

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