commit 3c8c81011048a4147aa399a8f89e1bdd81047ae0
author Paul Hu <paulhu@google.com> Thu Aug 25 07:06:16 2022 +0000
committer Paul Hu <paulhu@google.com> Tue Nov 22 07:08:05 2022 +0000
tree ad165c843275f39883e21382d12b0b6e2d7a8858
parent 41df7f99bb8a1b89da86b0afa8f6eb942c3b2e9c

Running PermissionMonitor#startMonitoring on handler thread

Most permission update functions are running on the handler
thread. So the startMonitoring() should be running on handler
thread as well to ensure the permission won't change while
processing CS's works.

However, startMonitoring() has a dependency with
MultipathPolicyTracker. It needs to call and complete the
permission update before calling MultipathPolicyTracker#start.
Thus, we need to check the startMonitoring done in the end of
systemReadyInternal because we are processing it on the handler
thread.

Bug: 232048835
Test: atest FrameworksNetTests CtsNetTestCases
Change-Id: I41fef14d6c163eb5676eab3ccd43416ea1fe1414

service/src/com/android/server/ConnectivityService.java

diff --git a/service/src/com/android/server/ConnectivityService.java b/service/src/com/android/server/ConnectivityService.java
index 2535974..dffe11d 100755
--- a/service/src/com/android/server/ConnectivityService.java
+++ b/service/src/com/android/server/ConnectivityService.java
@@ -211,6 +211,7 @@
 import android.os.Binder;
 import android.os.Build;
 import android.os.Bundle;
+import android.os.ConditionVariable;
 import android.os.Handler;
 import android.os.HandlerThread;
 import android.os.IBinder;
@@ -3040,7 +3041,11 @@
         // Calling PermissionMonitor#startMonitoring() in systemReadyInternal() and the
         // MultipathPolicyTracker.start() is called in NetworkPolicyManagerService#systemReady()
         // to ensure the tracking will be initialized correctly.
-        mPermissionMonitor.startMonitoring();
+        final ConditionVariable startMonitoringDone = new ConditionVariable();
+        mHandler.post(() -> {
+            mPermissionMonitor.startMonitoring();
+            startMonitoringDone.open();
+        });
         mProxyTracker.loadGlobalProxy();
         registerDnsResolverUnsolicitedEventListener();
 
@@ -3067,6 +3072,11 @@
         if (SdkLevel.isAtLeastT()) {
             mBpfNetMaps.setPullAtomCallback(mContext);
         }
+        // Wait PermissionMonitor to finish the permission update. Then MultipathPolicyTracker won't
+        // have permission problem. While CV#block() is unbounded in time and can in principle block
+        // forever, this replaces a synchronous call to PermissionMonitor#startMonitoring, which
+        // could have blocked forever too.
+        startMonitoringDone.block();
     }
 
     /**