linux-kernel - Re: [PATCH] ACPI: Remove the wakeup.run_wake

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Message-ID: <20110203112016.56ed35c3@jbarnes-desktop>
Date:	Thu, 3 Feb 2011 11:20:16 -0800
From:	Jesse Barnes <jbarnes@...tuousgeek.org>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	Len Brown <lenb@...nel.org>, Matthew Garrett <mjg59@...f.ucam.org>,
	Linux PM List <linux-pm@...ts.linux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	linux-pci@...r.kernel.org
Subject: Re: [PATCH] ACPI: Remove the wakeup.run_wake_count device field

On Thu, 3 Feb 2011 20:14:17 +0100
"Rafael J. Wysocki" <rjw@...k.pl> wrote:

> From: Rafael J. Wysocki <rjw@...k.pl>
> 
> The wakeup.run_wake_count ACPI device field is only used by the PCI
> runtime PM code to "protect" devices from being prepared for
> generating wakeup signals more than once in a row.  However, it
> really doesn't provide any protection, because (1) all of the
> functions it is supposed to protect use their own reference counters
> effectively ensuring that the device will be set up for generating
> wakeup signals just once and (2) the PCI runtime PM code uses
> wakeup.run_wake_count in a racy way, since nothing prevents
> acpi_dev_run_wake() from being called concurrently from two different
> threads for the same device.
> 
> Remove the wakeup.run_wake_count ACPI device field which is
> unnecessary, confusing and used in a wrong way.
> 
> Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
> ---
>  drivers/acpi/button.c   |    2 --
>  drivers/acpi/scan.c     |    1 -
>  drivers/pci/pci-acpi.c  |   16 ++++------------
>  include/acpi/acpi_bus.h |    1 -
>  4 files changed, 4 insertions(+), 16 deletions(-)

Ack on the PCI bits.

Acked-by: Jesse Barnes <jbarnes@...tuousgeek.org>

-- 
Jesse Barnes, Intel Open Source Technology Center
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