From cf601559d982f5270e48a888a8826b86b8afc2ee Mon Sep 17 00:00:00 2001
From: xshu <xshu@google.com>
Date: Thu, 30 Apr 2020 18:58:05 -0700
Subject: Fix WifiLockManager Death link does not exist

The cause of the issue is that sometimes WifiLocks are added without
linkToDeath working properly.

Catches the NoSuchElementException inside WifiLockManager to prevent
SystemServer from crashing.

Bug: 155240535
Test: atest com.android.server.wifi
Change-Id: Id9d56b9da184febef7915eb5281ea39f97e51b06
---
 .../java/com/android/server/wifi/WifiLockManager.java    |  9 +++++++--
 .../src/com/android/server/wifi/WifiLockManagerTest.java | 16 ++++++++++++++++
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/service/java/com/android/server/wifi/WifiLockManager.java b/service/java/com/android/server/wifi/WifiLockManager.java
index 7bbd3aa2e..7cbeea0d3 100644
--- a/service/java/com/android/server/wifi/WifiLockManager.java
+++ b/service/java/com/android/server/wifi/WifiLockManager.java
@@ -36,6 +36,7 @@ import com.android.server.wifi.util.WorkSourceUtil;
 import java.io.PrintWriter;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.NoSuchElementException;
 
 /**
  * WifiLockManager maintains the list of wake locks held by different applications.
@@ -189,7 +190,6 @@ public class WifiLockManager {
         // This is to make sure worksource value can not be changed by caller
         // after function returns.
         WorkSource newWorkSource = new WorkSource(ws);
-
         return addLock(new WifiLock(lockMode, tag, binder, newWorkSource));
     }
 
@@ -804,6 +804,7 @@ public class WifiLockManager {
             try {
                 mBinder.linkToDeath(this, 0);
             } catch (RemoteException e) {
+                Log.e(TAG, "mBinder.linkToDeath failed: " + e.getMessage());
                 binderDied();
             }
         }
@@ -829,7 +830,11 @@ public class WifiLockManager {
         }
 
         public void unlinkDeathRecipient() {
-            mBinder.unlinkToDeath(this, 0);
+            try {
+                mBinder.unlinkToDeath(this, 0);
+            } catch (NoSuchElementException e) {
+                Log.e(TAG, "mBinder.unlinkToDeath failed: " + e.getMessage());
+            }
         }
 
         public String toString() {
diff --git a/tests/wifitests/src/com/android/server/wifi/WifiLockManagerTest.java b/tests/wifitests/src/com/android/server/wifi/WifiLockManagerTest.java
index ed27d5041..40c47f4bf 100644
--- a/tests/wifitests/src/com/android/server/wifi/WifiLockManagerTest.java
+++ b/tests/wifitests/src/com/android/server/wifi/WifiLockManagerTest.java
@@ -41,6 +41,7 @@ import org.mockito.MockitoAnnotations;
 
 import java.io.PrintWriter;
 import java.io.StringWriter;
+import java.util.NoSuchElementException;
 
 /** Unit tests for {@link WifiLockManager}. */
 @SmallTest
@@ -1375,4 +1376,19 @@ public class WifiLockManagerTest extends WifiBaseTest {
                 + " uid=" + Binder.getCallingUid() + " workSource=WorkSource{"
                         + DEFAULT_TEST_UID_1 + "}"));
     }
+
+    /**
+     * Verify that an Exception in unlinkDeathRecipient is caught.
+     */
+    @Test
+    public void testUnlinkDeathRecipiientCatchesException() throws Exception {
+        acquireWifiLockSuccessful(WifiManager.WIFI_MODE_FULL_HIGH_PERF, "",
+                mBinder, mWorkSource);
+        assertEquals(WifiManager.WIFI_MODE_FULL_HIGH_PERF, mWifiLockManager.getStrongestLockMode());
+
+        doThrow(new NoSuchElementException()).when(mBinder).unlinkToDeath(any(), anyInt());
+        releaseLowLatencyWifiLockSuccessful(mBinder);
+        assertEquals(WifiManager.WIFI_MODE_NO_LOCKS_HELD,
+                mWifiLockManager.getStrongestLockMode());
+    }
 }
-- 
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