linux-kernel - Re: [Resend][PATCH] ACPI / EC: Remove race between EC driver and suspend process (rev. 3)

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 4 Mar 2010 09:32:03 +0000
From:	Alan Jenkins <sourcejedi.lkml@...glemail.com>
To:	Len Brown <lenb@...nel.org>
Cc:	"Rafael J. Wysocki" <rjw@...k.pl>,
	Alexey Starikovskiy <astarikovskiy@...e.de>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	pm list <linux-pm@...ts.linux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Maxim Levitsky <maximlevitsky@...il.com>
Subject: Re: [Resend][PATCH] ACPI / EC: Remove race between EC driver and 
	suspend process (rev. 3)

On 3/4/10, Len Brown <lenb@...nel.org> wrote:
> Isn't the problem at hand that the boot-kernel stops
> in mid-transaction, and the resumed hibernate image
> then blunders forward with its first transaction
> only to find the EC in an intermediate state?
>
> If yes, I then making the transaction atomic WRT
> the boot kernel stopping should fix the problem.
>
> The patch sets a FROZEN bit, and subsequent
> requests for EC transactions simply fail.
> How do we know that we set the bit at the right time?
> What transactions or parts of transactions will fail,
> and what are the consequences of those failures?

The problem transactions on my machine were probably started by
ec_check_sci().  I.e. QUERY transactions which read the value of an
event raised by the EC.  (I triggered the problem by pressing ACPI
hotkeys, although I haven't been able to reproduce it since).

That might explain why the transactions can be asynchronous with the
s2disk task - because these transactions are run in the ACPI
workqueue.  Perhaps the workqueue needs to be flushed after the EC GPE
is disabled?

Alan
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/