From e7ed20c00a681e2a7d08f4050c4583cb1f8748a6 Mon Sep 17 00:00:00 2001
From: Jerry Chang <chenghsiuchang@google.com>
Date: Mon, 14 Mar 2022 14:35:44 +0000
Subject: [PATCH] Prevent potential deadlock when sending pending intent in WCT

Post send pending intent while applying window container transaction to
prevent the potential deadlock between WindowManagerGlobalLock and
ActivityMangerService lock.

BYPASS_INCLUSIVE_LANGUAGE_REASON=using existing API.

Bug: 223365463
Test: pass existing tests
Test: manual check lock holding sequence and thread
Change-Id: I80f4671758dc930aa25381247280d44cccf4560c
---
 .../server/wm/WindowOrganizerController.java  | 60 +++++++++++--------
 1 file changed, 34 insertions(+), 26 deletions(-)

diff --git a/services/core/java/com/android/server/wm/WindowOrganizerController.java b/services/core/java/com/android/server/wm/WindowOrganizerController.java
index d862012942353..044da3982e268 100644
--- a/services/core/java/com/android/server/wm/WindowOrganizerController.java
+++ b/services/core/java/com/android/server/wm/WindowOrganizerController.java
@@ -94,6 +94,7 @@ import java.util.HashMap;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
+import java.util.function.IntSupplier;
 
 /**
  * Server side implementation for the interface for organizing windows
@@ -810,26 +811,8 @@ class WindowOrganizerController extends IWindowOrganizerController.Stub
                 launchOpts.remove(WindowContainerTransaction.HierarchyOp.LAUNCH_KEY_TASK_ID);
                 final SafeActivityOptions safeOptions =
                         SafeActivityOptions.fromBundle(launchOpts, caller.mPid, caller.mUid);
-                final Integer[] starterResult = {null};
-                // startActivityFromRecents should not be called in lock.
-                mService.mH.post(() -> {
-                    try {
-                        starterResult[0] = mService.mTaskSupervisor.startActivityFromRecents(
-                                caller.mPid, caller.mUid, taskId, safeOptions);
-                    } catch (Throwable t) {
-                        starterResult[0] = ActivityManager.START_CANCELED;
-                        Slog.w(TAG, t);
-                    }
-                    synchronized (mGlobalLock) {
-                        mGlobalLock.notifyAll();
-                    }
-                });
-                while (starterResult[0] == null) {
-                    try {
-                        mGlobalLock.wait();
-                    } catch (InterruptedException ignored) {
-                    }
-                }
+                waitAsyncStart(() -> mService.mTaskSupervisor.startActivityFromRecents(
+                        caller.mPid, caller.mUid, taskId, safeOptions));
                 break;
             }
             case HIERARCHY_OP_TYPE_PENDING_INTENT: {
@@ -838,22 +821,22 @@ class WindowOrganizerController extends IWindowOrganizerController.Stub
                         mService.mContext.getContentResolver())
                         : null;
 
-                Bundle options = null;
+                ActivityOptions activityOptions = null;
                 if (hop.getPendingIntent().isActivity()) {
                     // Set the context display id as preferred for this activity launches, so that
                     // it can land on caller's display. Or just brought the task to front at the
                     // display where it was on since it has higher preference.
-                    ActivityOptions activityOptions = hop.getLaunchOptions() != null
+                    activityOptions = hop.getLaunchOptions() != null
                             ? new ActivityOptions(hop.getLaunchOptions())
                             : ActivityOptions.makeBasic();
                     activityOptions.setCallerDisplayId(DEFAULT_DISPLAY);
-                    options = activityOptions.toBundle();
                 }
-
-                mService.mAmInternal.sendIntentSender(hop.getPendingIntent().getTarget(),
+                final Bundle options = activityOptions != null ? activityOptions.toBundle() : null;
+                waitAsyncStart(() -> mService.mAmInternal.sendIntentSender(
+                        hop.getPendingIntent().getTarget(),
                         hop.getPendingIntent().getWhitelistToken(), 0 /* code */,
                         hop.getActivityIntent(), resolvedType, null /* finishReceiver */,
-                        null /* requiredPermission */, options);
+                        null /* requiredPermission */, options));
                 break;
             }
             case HIERARCHY_OP_TYPE_START_SHORTCUT: {
@@ -914,6 +897,31 @@ class WindowOrganizerController extends IWindowOrganizerController.Stub
         return effects;
     }
 
+    /**
+     * Post and wait for the result of the activity start to prevent potential deadlock against
+     * {@link WindowManagerGlobalLock}.
+     */
+    private void waitAsyncStart(IntSupplier startActivity) {
+        final Integer[] starterResult = {null};
+        mService.mH.post(() -> {
+            try {
+                starterResult[0] = startActivity.getAsInt();
+            } catch (Throwable t) {
+                starterResult[0] = ActivityManager.START_CANCELED;
+                Slog.w(TAG, t);
+            }
+            synchronized (mGlobalLock) {
+                mGlobalLock.notifyAll();
+            }
+        });
+        while (starterResult[0] == null) {
+            try {
+                mGlobalLock.wait();
+            } catch (InterruptedException ignored) {
+            }
+        }
+    }
+
     private int sanitizeAndApplyHierarchyOp(WindowContainer container,
             WindowContainerTransaction.HierarchyOp hop) {
         final Task task = container.asTask();