Merge "Serialize AM.getContentProvider() calls in client side" into pi-dev

core/java/android/app/ActivityThread.java

@@ -347,6 +347,13 @@ public final class ActivityThread extends ClientTransactionHandler {
     final ArrayMap<ComponentName, ProviderClientRecord> mLocalProvidersByName
             = new ArrayMap<ComponentName, ProviderClientRecord>();
 
+    // Mitigation for b/74523247: Used to serialize calls to AM.getContentProvider().
+    // Note we never removes items from this map but that's okay because there are only so many
+    // users and so many authorities.
+    // TODO Remove it once we move CPR.wait() from AMS to the client side.
+    @GuardedBy("mGetProviderLocks")
+    final ArrayMap<ProviderKey, Object> mGetProviderLocks = new ArrayMap<>();
+
     final ArrayMap<Activity, ArrayList<OnActivityPausedListener>> mOnPauseListeners
         = new ArrayMap<Activity, ArrayList<OnActivityPausedListener>>();
 
@@ -5959,8 +5966,10 @@ public final class ActivityThread extends ClientTransactionHandler {
         // be re-entrant in the case where the provider is in the same process.
         ContentProviderHolder holder = null;
         try {
-            holder = ActivityManager.getService().getContentProvider(
-                    getApplicationThread(), auth, userId, stable);
+            synchronized (getGetProviderLock(auth, userId)) {
+                holder = ActivityManager.getService().getContentProvider(
+                        getApplicationThread(), auth, userId, stable);
+            }
         } catch (RemoteException ex) {
             throw ex.rethrowFromSystemServer();
         }
@@ -5976,6 +5985,18 @@ public final class ActivityThread extends ClientTransactionHandler {
         return holder.provider;
     }
 
+    private Object getGetProviderLock(String auth, int userId) {
+        final ProviderKey key = new ProviderKey(auth, userId);
+        synchronized (mGetProviderLocks) {
+            Object lock = mGetProviderLocks.get(key);
+            if (lock == null) {
+                lock = key;
+                mGetProviderLocks.put(key, lock);
+            }
+            return lock;
+        }
+    }
+
     private final void incProviderRefLocked(ProviderRefCount prc, boolean stable) {
         if (stable) {
             prc.stableCount += 1;