linux-kernel - [PATCH 2/2] ACPI / scan: Avoid enumerating devices more than once

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Date:   Mon, 17 Apr 2017 01:20:48 +0200
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Linux ACPI <linux-acpi@...r.kernel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: [PATCH 2/2] ACPI / scan: Avoid enumerating devices more than once

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

acpi_bus_attach() does not check the visited flag for devices that
have been enumerated already and some of them may be enumerated
for multiple times as a result, because some callers of
acpi_bus_scan() don't check the visited flag either.

For this reason, modify acpi_bus_attach() to check the visited flag
and avoid enumerating devices that have already been enumerated.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 drivers/acpi/scan.c |    2 ++
 1 file changed, 2 insertions(+)

Index: linux-pm/drivers/acpi/scan.c
===================================================================
--- linux-pm.orig/drivers/acpi/scan.c
+++ linux-pm/drivers/acpi/scan.c
@@ -1850,6 +1850,8 @@ static void acpi_bus_attach(struct acpi_
 			device->flags.power_manageable = 0;

 		device->flags.initialized = true;
+	} else if (device->flags.visited) {
+		goto ok;
 	}

 	ret = acpi_scan_attach_handler(device);