linux-kernel - [PATCH 1/3] ACPI / scan: Start matching drivers after trying scan handlers

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Message-ID: <3869743.TuXYQ2ebr5@vostro.rjw.lan>
Date:	Mon, 04 Nov 2013 01:18:50 +0100
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	ACPI Devel Maling List <linux-acpi@...r.kernel.org>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Linux PCI <linux-pci@...r.kernel.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Toshi Kani <toshi.kani@...com>, Yinghai Lu <yinghai@...nel.org>
Subject: [PATCH 1/3] ACPI / scan: Start matching drivers after trying scan handlers

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

ACPI scan handlers should always be attached to struct acpi_device
objects before any ACPI drivers, but there is a window during which
a driver may be attached to a struct acpi_device before checking if
there is a matching scan handler.  Namely, that will happen if an
ACPI driver module is loaded during acpi_bus_scan() right after
the first namespace walk is complete and before the given device
is processed by the second namespace walk.

To prevent that from happening, set the match_driver flags of
struct acpi_device objects right before running device_attach()
for them in acpi_bus_device_attach().

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 drivers/acpi/scan.c |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

Index: linux-pm/drivers/acpi/scan.c
===================================================================
--- linux-pm.orig/drivers/acpi/scan.c
+++ linux-pm/drivers/acpi/scan.c
@@ -1676,7 +1676,6 @@ void acpi_init_device_object(struct acpi
 
 void acpi_device_add_finalize(struct acpi_device *device)
 {
-	device->flags.match_driver = true;
 	dev_set_uevent_suppress(&device->dev, false);
 	kobject_uevent(&device->dev.kobj, KOBJ_ADD);
 }
@@ -1915,8 +1914,12 @@ static acpi_status acpi_bus_device_attac
 		return AE_OK;
 
 	ret = acpi_scan_attach_handler(device);
-	if (ret)
-		return ret > 0 ? AE_OK : AE_CTRL_DEPTH;
+	if (ret < 0)
+		return AE_CTRL_DEPTH;
+
+	device->flags.match_driver = true;
+	if (ret > 0)
+		return AE_OK;
 
 	ret = device_attach(&device->dev);
 	return ret >= 0 ? AE_OK : AE_CTRL_DEPTH;

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