2 files changed, 15 insertions, 1 deletions
diff --git a/services/core/java/com/android/server/am/ActivityManagerService.java b/services/core/java/com/android/server/am/ActivityManagerService.java
index 54c4ced18e47..e8c1a0f0e8b2 100644
--- a/services/core/java/com/android/server/am/ActivityManagerService.java
+++ b/services/core/java/com/android/server/am/ActivityManagerService.java
@@ -600,6 +600,8 @@ public final class ActivityManagerService extends ActivityManagerNative
 
     final AppErrors mAppErrors;
 
+    boolean mDoingSetFocusedActivity;
+
     public boolean canShowErrorDialogs() {
         return mShowDialogs && !mSleeping && !mShuttingDown;
     }
@@ -2730,6 +2732,12 @@ public final class ActivityManagerService extends ActivityManagerNative
         }
 
         if (DEBUG_FOCUS) Slog.d(TAG_FOCUS, "setFocusedActivityLocked: r=" + r);
+
+        final boolean wasDoingSetFocusedActivity = mDoingSetFocusedActivity;
+        if (wasDoingSetFocusedActivity) Slog.w(TAG,
+                "setFocusedActivityLocked: called recursively, r=" + r + ", reason=" + reason);
+        mDoingSetFocusedActivity = true;
+
         final ActivityRecord last = mFocusedActivity;
         mFocusedActivity = r;
         if (r.task.isApplicationTask()) {
@@ -2781,6 +2789,12 @@ public final class ActivityManagerService extends ActivityManagerNative
             mLastFocusedUserId = mFocusedActivity.userId;
         }
 
+        // Log a warning if the focused app is changed during the process. This could
+        // indicate a problem of the focus setting logic!
+        if (mFocusedActivity != r) Slog.w(TAG,
+                "setFocusedActivityLocked: r=" + r + " but focused to " + mFocusedActivity);
+        mDoingSetFocusedActivity = wasDoingSetFocusedActivity;
+
         EventLogTags.writeAmFocusedActivity(
                 mFocusedActivity == null ? -1 : mFocusedActivity.userId,
                 mFocusedActivity == null ? "NULL" : mFocusedActivity.shortComponentName,
diff --git a/services/core/java/com/android/server/am/ActivityStackSupervisor.java b/services/core/java/com/android/server/am/ActivityStackSupervisor.java
index 95bc95a8767a..e5ca1bfbaa9f 100644
--- a/services/core/java/com/android/server/am/ActivityStackSupervisor.java
+++ b/services/core/java/com/android/server/am/ActivityStackSupervisor.java
@@ -583,7 +583,7 @@ public final class ActivityStackSupervisor implements DisplayListener {
         }
 
         final ActivityRecord r = topRunningActivityLocked();
-        if (mService.mFocusedActivity != r) {
+        if (!mService.mDoingSetFocusedActivity && mService.mFocusedActivity != r) {
             // The focus activity should always be the top activity in the focused stack.
             // There will be chaos and anarchy if it isn't...
             mService.setFocusedActivityLocked(r, reason + " setFocusStack");