From d7616ef73c48a1e5d6ba0e36fc6e85b007832d25 Mon Sep 17 00:00:00 2001
From: Adam Lesinski <adamlesinski@google.com>
Date: Mon, 27 Jul 2015 11:43:05 -0700
Subject: [PATCH] BatteryStats: Prevent BatteryService from blocking

BatteryService is a low level service, and we shouldn't have it
block in BatteryStatsService while collecting external data from
components like WiFi. Deadlocks can occur this way.

Bug:22559655
Change-Id: I64026453d191695eb583a47163ab6f48f882b085
---
 .../server/am/BatteryStatsService.java        | 47 +++++++++++--------
 1 file changed, 28 insertions(+), 19 deletions(-)

diff --git a/services/core/java/com/android/server/am/BatteryStatsService.java b/services/core/java/com/android/server/am/BatteryStatsService.java
index 4b0b924e2ddbc..0707ec855b4de 100644
--- a/services/core/java/com/android/server/am/BatteryStatsService.java
+++ b/services/core/java/com/android/server/am/BatteryStatsService.java
@@ -854,26 +854,35 @@ public final class BatteryStatsService extends IBatteryStats.Stub
     public boolean isOnBattery() {
         return mStats.isOnBattery();
     }
-    
-    public void setBatteryState(int status, int health, int plugType, int level,
-            int temp, int volt) {
-        enforceCallingPermission();
-        synchronized (mStats) {
-            final boolean onBattery = plugType == BatteryStatsImpl.BATTERY_PLUGGED_NONE;
-            if (mStats.isOnBattery() == onBattery) {
-                // The battery state has not changed, so we don't need to sync external
-                // stats immediately.
-                mStats.setBatteryStateLocked(status, health, plugType, level, temp, volt);
-                return;
-            }
-        }
 
-        // Sync external stats first as the battery has changed states. If we don't sync
-        // immediately here, we may not collect the relevant data later.
-        updateExternalStats("battery-state", UPDATE_ALL);
-        synchronized (mStats) {
-            mStats.setBatteryStateLocked(status, health, plugType, level, temp, volt);
-        }
+    @Override
+    public void setBatteryState(final int status, final int health, final int plugType,
+                                final int level, final int temp, final int volt) {
+        enforceCallingPermission();
+
+        // BatteryService calls us here and we may update external state. It would be wrong
+        // to block such a low level service like BatteryService on external stats like WiFi.
+        mHandler.post(new Runnable() {
+            @Override
+            public void run() {
+                synchronized (mStats) {
+                    final boolean onBattery = plugType == BatteryStatsImpl.BATTERY_PLUGGED_NONE;
+                    if (mStats.isOnBattery() == onBattery) {
+                        // The battery state has not changed, so we don't need to sync external
+                        // stats immediately.
+                        mStats.setBatteryStateLocked(status, health, plugType, level, temp, volt);
+                        return;
+                    }
+                }
+
+                // Sync external stats first as the battery has changed states. If we don't sync
+                // immediately here, we may not collect the relevant data later.
+                updateExternalStats("battery-state", UPDATE_ALL);
+                synchronized (mStats) {
+                    mStats.setBatteryStateLocked(status, health, plugType, level, temp, volt);
+                }
+            }
+        });
     }
     
     public long getAwakeTimeBattery() {