linux-kernel - [PATCH] ACPI / scan: Treat power resources in a special way

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Date:	Mon, 31 Dec 2012 01:46:37 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	ACPI Devel Maling List <linux-acpi@...r.kernel.org>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Yinghai Lu <yinghai@...nel.org>, Jiang Liu <liuj97@...il.com>,
	Toshi Kani <toshi.kani@...com>
Subject: [PATCH] ACPI / scan: Treat power resources in a special way

From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

Commit 1d57433 (ACPI: Separate adding ACPI device objects from
probing ACPI drivers) introduced an ACPI power resources management
regression, because it didn't ensure that the power resources
driver bind to the struct acpi_device objects corresponding
to power resources as soon as they were created.  As a result,
ACPI power management routines may attempt to access power resource
objects before they are ready to use.

To fix this problem, tell the acpi_add_single_object() in
acpi_bus_check_add() to probe the driver for objects of type
ACPI_BUS_TYPE_POWER.  This fix has been verified to work on
HP nx6325 where the problem was first observed.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---

The commit mentioned in the changelog is in linux-next only for now, but
it's likely to go upstream in this form anyway and the fix on top of the
whole ACPI scan series is trivial.

Thanks,
Rafael

---
 drivers/acpi/scan.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Index: linux/drivers/acpi/scan.c
===================================================================
--- linux.orig/drivers/acpi/scan.c
+++ linux/drivers/acpi/scan.c
@@ -1606,7 +1606,8 @@ static acpi_status acpi_bus_check_add(ac
 		return AE_CTRL_DEPTH;
 	}

-	acpi_add_single_object(&device, handle, type, sta, false);
+	acpi_add_single_object(&device, handle, type, sta,
+			       type == ACPI_BUS_TYPE_POWER);
 	if (!device)
 		return AE_CTRL_DEPTH;

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