commit 88b85e1f9b2fb3cf1ab9da1967e1d454be2d5be0
author Robert Carr <racarr@google.com> Mon Mar 21 15:47:35 2022 -0700
committer Rob Carr <racarr@google.com> Tue Mar 22 22:56:25 2022 +0000
tree 982ecba4a76554b8bb3af9854bd3025f8973357b
parent f4b49765605223dba7b804c351a98a3c6bb676f9

SurfaceFlinger: Detect Rel Z loops

Telemetry indicates we are sometimes seeing crashes
due to infinite recursion in isHiddenByPolicy. We detect this
condition (relative Z loop) and add a helpful log. The performance
impact should be minimal as relative Z is rare, and
the traversal isn't doing any heavy work or sp<> promotion.

Bug: 213420016
Bug: 195298154
Bug: 219774897
Test: Existing tests pass
Change-Id: Ia11854654e99288c5846fe7c62ebabf37daeb139

services/surfaceflinger/Layer.h

diff --git a/services/surfaceflinger/Layer.h b/services/surfaceflinger/Layer.h
index 48a9bc5..846460d 100644
--- a/services/surfaceflinger/Layer.h
+++ b/services/surfaceflinger/Layer.h
@@ -1138,6 +1138,7 @@
     bool mIsAtRoot = false;
 
     uint32_t mLayerCreationFlags;
+    bool findInHierarchy(const sp<Layer>&);
 };
 
 std::ostream& operator<<(std::ostream& stream, const Layer::FrameRate& rate);