ACPI PM: Replace wakeup.prepared with reference counter

The wakeup.prepared flag is used for marking devices that have the
wake-up power already enabled, so that the wake-up power is not
enabled twice in a row for the same device.  This assumes, however,
that device wake-up power will only be enabled once, while the device
is being prepared for a system-wide sleep transition, and the second
attempt is made by acpi_enable_wakeup_device_prep().

With the upcoming PCI wake-up rework this assumption will not hold
any more for PCI bridges and the root bridge whose wake-up power
may be enabled as a result of wake-up enable propagation from other
devices (eg. add-on devices that are not associated with any GPEs).
Thus, there may be many attempts to enable wake-up power on a PCI
bridge or the root bridge during a system power state transition
and it's better to replace wakeup.prepared with a reference counter.

Reviewed-by: Matthew Garrett <mjg59@srcf.ucam.org>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

1 files changed, 35 insertions, 23 deletions

diff --git a/drivers/acpi/power.c b/drivers/acpi/power.c
index d74365d4a6e7..5a09bf392ec1 100644
--- a/drivers/acpi/power.c
+++ b/drivers/acpi/power.c
@@ -44,6 +44,8 @@
 #include <acpi/acpi_bus.h>
 #include <acpi/acpi_drivers.h>
 
+#include "sleep.h"
+
 #define _COMPONENT			ACPI_POWER_COMPONENT
 ACPI_MODULE_NAME("power");
 #define ACPI_POWER_CLASS		"power_resource"
@@ -361,17 +363,15 @@ int acpi_device_sleep_wake(struct acpi_device *dev,
  */
 int acpi_enable_wakeup_device_power(struct acpi_device *dev, int sleep_state)
 {
-	int i, err;
+	int i, err = 0;
 
 	if (!dev || !dev->wakeup.flags.valid)
 		return -EINVAL;
 
-	/*
-	 * Do not execute the code below twice in a row without calling
-	 * acpi_disable_wakeup_device_power() in between for the same device
-	 */
-	if (dev->wakeup.flags.prepared)
-		return 0;
+	mutex_lock(&acpi_device_lock);
+
+	if (dev->wakeup.prepare_count++)
+		goto out;
 
 	/* Open power resource */
 	for (i = 0; i < dev->wakeup.resources.count; i++) {
@@ -379,7 +379,8 @@ int acpi_enable_wakeup_device_power(struct acpi_device *dev, int sleep_state)
 		if (ret) {
 			printk(KERN_ERR PREFIX "Transition power state\n");
 			dev->wakeup.flags.valid = 0;
-			return -ENODEV;
+			err = -ENODEV;
+			goto err_out;
 		}
 	}
 
@@ -388,9 +389,13 @@ int acpi_enable_wakeup_device_power(struct acpi_device *dev, int sleep_state)
 	 * in arbitrary power state afterwards.
 	 */
 	err = acpi_device_sleep_wake(dev, 1, sleep_state, 3);
-	if (!err)
-		dev->wakeup.flags.prepared = 1;
 
+ err_out:
+	if (err)
+		dev->wakeup.prepare_count = 0;
+
+ out:
+	mutex_unlock(&acpi_device_lock);
 	return err;
 }
 
@@ -402,35 +407,42 @@ int acpi_enable_wakeup_device_power(struct acpi_device *dev, int sleep_state)
  */
 int acpi_disable_wakeup_device_power(struct acpi_device *dev)
 {
-	int i, ret;
+	int i, err = 0;
 
 	if (!dev || !dev->wakeup.flags.valid)
 		return -EINVAL;
 
+	mutex_lock(&acpi_device_lock);
+
+	if (--dev->wakeup.prepare_count > 0)
+		goto out;
+
 	/*
-	 * Do not execute the code below twice in a row without calling
-	 * acpi_enable_wakeup_device_power() in between for the same device
+	 * Executing the code below even if prepare_count is already zero when
+	 * the function is called may be useful, for example for initialisation.
 	 */
-	if (!dev->wakeup.flags.prepared)
-		return 0;
+	if (dev->wakeup.prepare_count < 0)
+		dev->wakeup.prepare_count = 0;
 
-	dev->wakeup.flags.prepared = 0;
-
-	ret = acpi_device_sleep_wake(dev, 0, 0, 0);
-	if (ret)
-		return ret;
+	err = acpi_device_sleep_wake(dev, 0, 0, 0);
+	if (err)
+		goto out;
 
 	/* Close power resource */
 	for (i = 0; i < dev->wakeup.resources.count; i++) {
-		ret = acpi_power_off_device(dev->wakeup.resources.handles[i], dev);
+		int ret = acpi_power_off_device(
+				dev->wakeup.resources.handles[i], dev);
 		if (ret) {
 			printk(KERN_ERR PREFIX "Transition power state\n");
 			dev->wakeup.flags.valid = 0;
-			return -ENODEV;
+			err = -ENODEV;
+			goto out;
 		}
 	}
 
-	return ret;
+ out:
+	mutex_unlock(&acpi_device_lock);
+	return err;
 }
 
 /* --------------------------------------------------------------------------