Merge "Fix Deadlock Issue On AppFuseBridge" into rvc-dev

2 files changed, 30 insertions, 0 deletions

diff --git a/services/core/java/com/android/server/storage/AppFuseBridge.java b/services/core/java/com/android/server/storage/AppFuseBridge.java
index 9d6a64701e85..b00540fd2a52 100644
--- a/services/core/java/com/android/server/storage/AppFuseBridge.java
+++ b/services/core/java/com/android/server/storage/AppFuseBridge.java
@@ -56,6 +56,15 @@ public class AppFuseBridge implements Runnable {
 
     public ParcelFileDescriptor addBridge(MountScope mountScope)
             throws FuseUnavailableMountException, NativeDaemonConnectorException {
+        /*
+        ** Dead Lock between Java lock (AppFuseBridge.java) and Native lock (FuseBridgeLoop.cc)
+        **
+        **  (Thread A) Got Java lock (addBrdige) -> Try to get Native lock (native_add_brdige)
+        **  (Thread B)        Got Native lock (FuseBrdigeLoop.start) -> Try to get Java lock (onClosed)
+        **
+        ** Guarantee the lock order (native lock -> java lock) when adding Bridge.
+        */
+        native_lock();
         try {
             synchronized (this) {
                 Preconditions.checkArgument(mScopes.indexOfKey(mountScope.mountId) < 0);
@@ -73,6 +82,7 @@ public class AppFuseBridge implements Runnable {
                 return result;
             }
         } finally {
+            native_unlock();
             IoUtils.closeQuietly(mountScope);
         }
     }
@@ -159,4 +169,6 @@ public class AppFuseBridge implements Runnable {
     private native void native_delete(long loop);
     private native void native_start_loop(long loop);
     private native int native_add_bridge(long loop, int mountId, int deviceId);
+    private native void native_lock();
+    private native void native_unlock();
 }
diff --git a/services/core/jni/com_android_server_storage_AppFuseBridge.cpp b/services/core/jni/com_android_server_storage_AppFuseBridge.cpp
index e51963340ae1..20210abd0ea8 100644
--- a/services/core/jni/com_android_server_storage_AppFuseBridge.cpp
+++ b/services/core/jni/com_android_server_storage_AppFuseBridge.cpp
@@ -123,6 +123,14 @@ jint com_android_server_storage_AppFuseBridge_add_bridge(
     return proxyFd[1].release();
 }
 
+void com_android_server_storage_AppFuseBridge_lock(JNIEnv* env, jobject self) {
+    fuse::FuseBridgeLoop::Lock();
+}
+
+void com_android_server_storage_AppFuseBridge_unlock(JNIEnv* env, jobject self) {
+    fuse::FuseBridgeLoop::Unlock();
+}
+
 const JNINativeMethod methods[] = {
     {
         "native_new",
@@ -143,6 +151,16 @@ const JNINativeMethod methods[] = {
         "native_add_bridge",
         "(JII)I",
         reinterpret_cast<void*>(com_android_server_storage_AppFuseBridge_add_bridge)
+    },
+    {
+        "native_lock",
+        "()V",
+        reinterpret_cast<void*>(com_android_server_storage_AppFuseBridge_lock)
+    },
+    {
+        "native_unlock",
+        "()V",
+        reinterpret_cast<void*>(com_android_server_storage_AppFuseBridge_unlock)
     }
 };