Avoid lock inversion.

The PowerManager lock (which is used in the Battery Saver code) sits
low in the lock hierarchy. NotificationManagerService is higher, so
nothing should call into NotificationManagerService with the
PowerManager lock held. This change calls into NMS on a background
thread so that the call occurs without the PM lock held.

Also fixing the cancel notification bug. We create the notifications
using notifyAsUser(... UserHandle.ALL). The cancel() call wasn't
properly dismissing the notification. Switching to
cancelAsUser(UserHandle.ALL) fixes the issue.

Bug: 145886051
Test: atest BatterySaverStateMachineTest
Test: Manually ensure notification disappears when BS turns on
Change-Id: I3315357e810d92938e4a34929235d233b07deebb

1 files changed, 40 insertions, 27 deletions

diff --git a/services/core/java/com/android/server/power/batterysaver/BatterySaverStateMachine.java b/services/core/java/com/android/server/power/batterysaver/BatterySaverStateMachine.java
index ff9129956a3b..a62bb74730f8 100644
--- a/services/core/java/com/android/server/power/batterysaver/BatterySaverStateMachine.java
+++ b/services/core/java/com/android/server/power/batterysaver/BatterySaverStateMachine.java
@@ -773,9 +773,9 @@ public class BatterySaverStateMachine {
 
         // Handle triggering the notification to show/hide when appropriate
         if (intReason == BatterySaverController.REASON_DYNAMIC_POWER_SAVINGS_AUTOMATIC_ON) {
-            runOnBgThread(this::triggerDynamicModeNotification);
+            triggerDynamicModeNotification();
         } else if (!enable) {
-            runOnBgThread(this::hideDynamicModeNotification);
+            hideDynamicModeNotification();
         }
 
         if (DEBUG) {
@@ -787,33 +787,42 @@ public class BatterySaverStateMachine {
 
     @VisibleForTesting
     void triggerDynamicModeNotification() {
-        NotificationManager manager = mContext.getSystemService(NotificationManager.class);
-        ensureNotificationChannelExists(manager, DYNAMIC_MODE_NOTIF_CHANNEL_ID,
-                R.string.dynamic_mode_notification_channel_name);
-
-        manager.notifyAsUser(TAG, DYNAMIC_MODE_NOTIFICATION_ID,
-                buildNotification(DYNAMIC_MODE_NOTIF_CHANNEL_ID,
-                        mContext.getResources().getString(R.string.dynamic_mode_notification_title),
-                        R.string.dynamic_mode_notification_summary,
-                        Intent.ACTION_POWER_USAGE_SUMMARY),
-                UserHandle.ALL);
+        // The current lock is the PowerManager lock, which sits very low in the service lock
+        // hierarchy. We shouldn't call out to NotificationManager with the PowerManager lock.
+        runOnBgThread(() -> {
+            NotificationManager manager = mContext.getSystemService(NotificationManager.class);
+            ensureNotificationChannelExists(manager, DYNAMIC_MODE_NOTIF_CHANNEL_ID,
+                    R.string.dynamic_mode_notification_channel_name);
+
+            manager.notifyAsUser(TAG, DYNAMIC_MODE_NOTIFICATION_ID,
+                    buildNotification(DYNAMIC_MODE_NOTIF_CHANNEL_ID,
+                            mContext.getResources().getString(
+                                    R.string.dynamic_mode_notification_title),
+                            R.string.dynamic_mode_notification_summary,
+                            Intent.ACTION_POWER_USAGE_SUMMARY),
+                    UserHandle.ALL);
+        });
     }
 
     @VisibleForTesting
     void triggerStickyDisabledNotification() {
-        NotificationManager manager = mContext.getSystemService(NotificationManager.class);
-        ensureNotificationChannelExists(manager, BATTERY_SAVER_NOTIF_CHANNEL_ID,
-                R.string.battery_saver_notification_channel_name);
-
-        final String percentage = NumberFormat.getPercentInstance()
-                .format((double) mBatteryLevel / 100.0);
-        manager.notifyAsUser(TAG, STICKY_AUTO_DISABLED_NOTIFICATION_ID,
-                buildNotification(BATTERY_SAVER_NOTIF_CHANNEL_ID,
-                        mContext.getResources().getString(
-                                R.string.battery_saver_charged_notification_title, percentage),
-                        R.string.battery_saver_off_notification_summary,
-                        Settings.ACTION_BATTERY_SAVER_SETTINGS),
-                UserHandle.ALL);
+        // The current lock is the PowerManager lock, which sits very low in the service lock
+        // hierarchy. We shouldn't call out to NotificationManager with the PowerManager lock.
+        runOnBgThread(() -> {
+            NotificationManager manager = mContext.getSystemService(NotificationManager.class);
+            ensureNotificationChannelExists(manager, BATTERY_SAVER_NOTIF_CHANNEL_ID,
+                    R.string.battery_saver_notification_channel_name);
+
+            final String percentage = NumberFormat.getPercentInstance()
+                    .format((double) mBatteryLevel / 100.0);
+            manager.notifyAsUser(TAG, STICKY_AUTO_DISABLED_NOTIFICATION_ID,
+                    buildNotification(BATTERY_SAVER_NOTIF_CHANNEL_ID,
+                            mContext.getResources().getString(
+                                    R.string.battery_saver_charged_notification_title, percentage),
+                            R.string.battery_saver_off_notification_summary,
+                            Settings.ACTION_BATTERY_SAVER_SETTINGS),
+                    UserHandle.ALL);
+        });
     }
 
     private void ensureNotificationChannelExists(NotificationManager manager,
@@ -854,8 +863,12 @@ public class BatterySaverStateMachine {
     }
 
     private void hideNotification(int notificationId) {
-        NotificationManager manager = mContext.getSystemService(NotificationManager.class);
-        manager.cancel(notificationId);
+        // The current lock is the PowerManager lock, which sits very low in the service lock
+        // hierarchy. We shouldn't call out to NotificationManager with the PowerManager lock.
+        runOnBgThread(() -> {
+            NotificationManager manager = mContext.getSystemService(NotificationManager.class);
+            manager.cancelAsUser(TAG, notificationId, UserHandle.ALL);
+        });
     }
 
     private void setStickyActive(boolean active) {