From 6e5eb1dfa6b73e0f6f4dc98baf88a9826e2f1d25 Mon Sep 17 00:00:00 2001
From: Makoto Onuki <omakoto@google.com>
Date: Fri, 30 Mar 2018 16:15:35 -0700
Subject: [PATCH] Fix dead lock between AM and BatterySaverStateMachine

Change-Id: If641ad1a0961376de65fdb9d557e7e2e601af389
Fixes: 77308319
Test: Boot, toggle battery saver
Test: atest $ANDROID_BUILD_TOP/frameworks/base/services/tests/servicestests/src/com/android/server/power/batterysaver/BatterySaverStateMachineTest.java
---
 .../batterysaver/BatterySaverStateMachine.java     | 39 +++++++++++++---------
 .../batterysaver/BatterySaverStateMachineTest.java |  5 +++
 2 files changed, 29 insertions(+), 15 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 5b3182ebd699..28605215e19d 100644
--- a/services/core/java/com/android/server/power/batterysaver/BatterySaverStateMachine.java
+++ b/services/core/java/com/android/server/power/batterysaver/BatterySaverStateMachine.java
@@ -26,6 +26,7 @@ import android.util.proto.ProtoOutputStream;
 
 import com.android.internal.annotations.GuardedBy;
 import com.android.internal.annotations.VisibleForTesting;
+import com.android.internal.os.BackgroundThread;
 import com.android.server.power.BatterySaverPolicy;
 import com.android.server.power.BatterySaverStateMachineProto;
 
@@ -124,25 +125,33 @@ public class BatterySaverStateMachine {
         if (DEBUG) {
             Slog.d(TAG, "onBootCompleted");
         }
-        synchronized (mLock) {
+        // This is called with the power manager lock held. Don't do any
+        runOnBgThread(() -> {
+            synchronized (mLock) {
 
-            final ContentResolver cr = mContext.getContentResolver();
-            cr.registerContentObserver(Settings.Global.getUriFor(
-                    Settings.Global.LOW_POWER_MODE),
-                    false, mSettingsObserver, UserHandle.USER_SYSTEM);
-            cr.registerContentObserver(Settings.Global.getUriFor(
-                    Settings.Global.LOW_POWER_MODE_STICKY),
-                    false, mSettingsObserver, UserHandle.USER_SYSTEM);
-            cr.registerContentObserver(Settings.Global.getUriFor(
-                    Settings.Global.LOW_POWER_MODE_TRIGGER_LEVEL),
-                    false, mSettingsObserver, UserHandle.USER_SYSTEM);
+                final ContentResolver cr = mContext.getContentResolver();
+                cr.registerContentObserver(Settings.Global.getUriFor(
+                        Settings.Global.LOW_POWER_MODE),
+                        false, mSettingsObserver, UserHandle.USER_SYSTEM);
+                cr.registerContentObserver(Settings.Global.getUriFor(
+                        Settings.Global.LOW_POWER_MODE_STICKY),
+                        false, mSettingsObserver, UserHandle.USER_SYSTEM);
+                cr.registerContentObserver(Settings.Global.getUriFor(
+                        Settings.Global.LOW_POWER_MODE_TRIGGER_LEVEL),
+                        false, mSettingsObserver, UserHandle.USER_SYSTEM);
 
-            mBootCompleted = true;
+                mBootCompleted = true;
 
-            refreshSettingsLocked();
+                refreshSettingsLocked();
 
-            doAutoBatterySaverLocked();
-        }
+                doAutoBatterySaverLocked();
+            }
+        });
+    }
+
+    @VisibleForTesting
+    void runOnBgThread(Runnable r) {
+        BackgroundThread.getHandler().post(r);
     }
 
     void refreshSettingsLocked() {
diff --git a/services/tests/servicestests/src/com/android/server/power/batterysaver/BatterySaverStateMachineTest.java b/services/tests/servicestests/src/com/android/server/power/batterysaver/BatterySaverStateMachineTest.java
index ab640d66b222..1367f583ba38 100644
--- a/services/tests/servicestests/src/com/android/server/power/batterysaver/BatterySaverStateMachineTest.java
+++ b/services/tests/servicestests/src/com/android/server/power/batterysaver/BatterySaverStateMachineTest.java
@@ -139,6 +139,11 @@ public class BatterySaverStateMachineTest {
         protected int getGlobalSetting(String key, int defValue) {
             return mDevice.getGlobalSetting(key, defValue);
         }
+
+        @Override
+        void runOnBgThread(Runnable r) {
+            r.run();
+        }
     }
 
     @Before
-- 
2.11.0