From d781ff68f1b4eefebac0ddf3372f1c33c5153e4a Mon Sep 17 00:00:00 2001
From: Kalesh Singh <kaleshsingh@google.com>
Date: Thu, 9 Jul 2020 20:13:30 +0000
Subject: [PATCH] Don't cache suspend_control service

Caching a reference to the service can lead to a DeadObject if
if the service was restarted. Additially we attempt to wait for
the service if it is not immediately available.

Bug: 160741383
Test: atest FrameworksCoreTests:KernelWakelockReaderTest

Change-Id: If54d644a66bed8a0da6a2f5b34168cad8f954187
---
 .../internal/os/KernelWakelockReader.java     | 29 ++++++++++++++-----
 1 file changed, 21 insertions(+), 8 deletions(-)

diff --git a/core/java/com/android/internal/os/KernelWakelockReader.java b/core/java/com/android/internal/os/KernelWakelockReader.java
index cffb0ad9fdb99..3d35d2fbaa826 100644
--- a/core/java/com/android/internal/os/KernelWakelockReader.java
+++ b/core/java/com/android/internal/os/KernelWakelockReader.java
@@ -152,20 +152,33 @@ public class KernelWakelockReader {
         }
     }
 
+    /**
+     * Attempt to wait for suspend_control service if not immediately available.
+     */
+    private ISuspendControlService waitForSuspendControlService() throws ServiceNotFoundException {
+        final String name = "suspend_control";
+        final int numRetries = 5;
+        for (int i = 0; i < numRetries; i++) {
+            mSuspendControlService = ISuspendControlService.Stub.asInterface(
+                                        ServiceManager.getService(name));
+            if (mSuspendControlService != null) {
+                return mSuspendControlService;
+            }
+        }
+        throw new ServiceNotFoundException(name);
+    }
+
     /**
      * On success, returns the updated stats from SystemSupend, else returns null.
      */
     private KernelWakelockStats getWakelockStatsFromSystemSuspend(
             final KernelWakelockStats staleStats) {
         WakeLockInfo[] wlStats = null;
-        if (mSuspendControlService == null) {
-            try {
-                mSuspendControlService = ISuspendControlService.Stub.asInterface(
-                    ServiceManager.getServiceOrThrow("suspend_control"));
-            } catch (ServiceNotFoundException e) {
-                Slog.wtf(TAG, "Required service suspend_control not available", e);
-                return null;
-            }
+        try {
+            mSuspendControlService = waitForSuspendControlService();
+        } catch (ServiceNotFoundException e) {
+            Slog.wtf(TAG, "Required service suspend_control not available", e);
+            return null;
         }
 
         try {