Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit bb2ec6a4 authored by Melody Hsu's avatar Melody Hsu
Browse files

Log detected cycles in LayerHierarchy#traverse 

Prevents a stack overflow in the event of a cyclic
hierarchy.

Fixes: b/341182047
Test: atest SurfaceFlinger_test
Change-Id: I930cda6258cdabe0bdc98bd68bdd88f1de7c1a8c
parent 81afac91

services/surfaceflinger/FrontEnd/LayerHierarchy.cpp

+7 −3
Original line number Diff line number Diff line
@@ -52,8 +52,12 @@ LayerHierarchy::LayerHierarchy(const LayerHierarchy& hierarchy, bool childrenOnl 
    mChildren = hierarchy.mChildren;

}



void LayerHierarchy::traverse(const Visitor& visitor,

                              LayerHierarchy::TraversalPath& traversalPath) const {

void LayerHierarchy::traverse(const Visitor& visitor, LayerHierarchy::TraversalPath& traversalPath,

                              uint32_t depth) const {

    LLOG_ALWAYS_FATAL_WITH_TRACE_IF(depth > 50,

                                    "Cycle detected in LayerHierarchy::traverse. See "

                                    "traverse_stack_overflow_transactions.winscope");



    if (mLayer) {

        bool breakTraversal = !visitor(*this, traversalPath);

        if (breakTraversal) {
@@ -66,7 +70,7 @@ void LayerHierarchy::traverse(const Visitor& visitor, 
    for (auto& [child, childVariant] : mChildren) {

        ScopedAddToTraversalPath addChildToTraversalPath(traversalPath, child->mLayer->id,

                                                         childVariant);

        child->traverse(visitor, traversalPath);

        child->traverse(visitor, traversalPath, depth + 1);

    }

}

services/surfaceflinger/FrontEnd/LayerHierarchy.h

+3 −2
Original line number Diff line number Diff line
@@ -147,7 +147,7 @@ public: 
        if (mLayer) {

            root.id = mLayer->id;

        }

        traverse(visitor, root);

        traverse(visitor, root, /*depth=*/0);

    }



    // Traverse the hierarchy in z-order, skipping children that have relative parents.
@@ -190,7 +190,8 @@ private: 
    void sortChildrenByZOrder();

    void updateChild(LayerHierarchy*, LayerHierarchy::Variant);

    void traverseInZOrder(const Visitor& visitor, LayerHierarchy::TraversalPath& parent) const;

    void traverse(const Visitor& visitor, LayerHierarchy::TraversalPath& parent) const;

    void traverse(const Visitor& visitor, LayerHierarchy::TraversalPath& parent,

                  uint32_t depth = 0) const;

    void dump(std::ostream& out, const std::string& prefix, LayerHierarchy::Variant variant,

              bool isLastChild, bool includeMirroredHierarchy) const;