From 8312b1d2c1338c7519494d3341164a1a2aee6820 Mon Sep 17 00:00:00 2001
From: Winson Chung <winsonc@google.com>
Date: Mon, 24 Jun 2019 11:57:22 -0700
Subject: [PATCH] Fix crash while animating removed stack

Bug: 135711060
Test: atest PinnedStackTests
Change-Id: Ie1f3acb9d2152435dc018360ad5120f1ee678d3c
---
 services/core/java/com/android/server/wm/TaskStack.java | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/services/core/java/com/android/server/wm/TaskStack.java b/services/core/java/com/android/server/wm/TaskStack.java
index 481c3ba24fcad..114a56feaf73e 100644
--- a/services/core/java/com/android/server/wm/TaskStack.java
+++ b/services/core/java/com/android/server/wm/TaskStack.java
@@ -1936,8 +1936,12 @@ public class TaskStack extends WindowContainer<Task> implements
     public boolean setPinnedStackAlpha(float alpha) {
         // Hold the lock since this is called from the BoundsAnimator running on the UiThread
         synchronized (mWmService.mGlobalLock) {
-            getPendingTransaction().setAlpha(getSurfaceControl(),
-                    mCancelCurrentBoundsAnimation ? 1 : alpha);
+            final SurfaceControl sc = getSurfaceControl();
+            if (sc == null || !sc.isValid()) {
+                // If the stack is already removed, don't bother updating any stack animation
+                return false;
+            }
+            getPendingTransaction().setAlpha(sc, mCancelCurrentBoundsAnimation ? 1 : alpha);
             scheduleAnimation();
             return !mCancelCurrentBoundsAnimation;
         }