From 73360ab2d12645a177e8e3d860dec3407839ad76 Mon Sep 17 00:00:00 2001
From: Makoto Onuki <omakoto@google.com>
Date: Fri, 17 Mar 2017 11:50:13 -0700
Subject: [PATCH] Fix deadlock between activity manager and settings provider

Test: manual
Bug 36028906

Change-Id: I20344608d79d174b468506056789c04d3bde510f
---
 .../android/providers/settings/SettingsProvider.java   | 10 ++++++++--
 .../android/server/am/ActivityManagerConstants.java    |  6 +++---
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/packages/SettingsProvider/src/com/android/providers/settings/SettingsProvider.java b/packages/SettingsProvider/src/com/android/providers/settings/SettingsProvider.java
index 91a4e792bbb81..1f1c18976edf1 100644
--- a/packages/SettingsProvider/src/com/android/providers/settings/SettingsProvider.java
+++ b/packages/SettingsProvider/src/com/android/providers/settings/SettingsProvider.java
@@ -248,6 +248,9 @@ public class SettingsProvider extends ContentProvider {
     @GuardedBy("mLock")
     private HandlerThread mHandlerThread;
 
+    @GuardedBy("mLock")
+    private Handler mHandler;
+
     // We have to call in the user manager with no lock held,
     private volatile UserManager mUserManager;
 
@@ -300,10 +303,13 @@ public class SettingsProvider extends ContentProvider {
             mHandlerThread = new HandlerThread(LOG_TAG,
                     Process.THREAD_PRIORITY_BACKGROUND);
             mHandlerThread.start();
+            mHandler = new Handler(mHandlerThread.getLooper());
             mSettingsRegistry = new SettingsRegistry();
         }
-        registerBroadcastReceivers();
-        startWatchingUserRestrictionChanges();
+        mHandler.post(() -> {
+            registerBroadcastReceivers();
+            startWatchingUserRestrictionChanges();
+        });
         ServiceManager.addService("settings", new SettingsService(this));
         return true;
     }
diff --git a/services/core/java/com/android/server/am/ActivityManagerConstants.java b/services/core/java/com/android/server/am/ActivityManagerConstants.java
index 100d8212eaccc..df250b19beba1 100644
--- a/services/core/java/com/android/server/am/ActivityManagerConstants.java
+++ b/services/core/java/com/android/server/am/ActivityManagerConstants.java
@@ -105,16 +105,16 @@ final class ActivityManagerConstants extends ContentObserver {
     }
 
     private void updateConstants() {
+        final String setting = Settings.Global.getString(mResolver,
+                Settings.Global.ACTIVITY_MANAGER_CONSTANTS);
         synchronized (mService) {
             try {
-                mParser.setString(Settings.Global.getString(mResolver,
-                        Settings.Global.ACTIVITY_MANAGER_CONSTANTS));
+                mParser.setString(setting);
             } catch (IllegalArgumentException e) {
                 // Failed to parse the settings string, log this and move on
                 // with defaults.
                 Slog.e("ActivityManagerConstants", "Bad activity manager config settings", e);
             }
-
             ENFORCE_BG_CHECK = mParser.getBoolean(KEY_ENFORCE_BG_CHECK, DEFAULT_ENFORCE_BG_CHECK);
             MAX_CACHED_PROCESSES = mParser.getInt(KEY_MAX_CACHED_PROCESSES,
                     DEFAULT_MAX_CACHED_PROCESSES);