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Commit 0ece7b9d authored by Stan Iliev's avatar Stan Iliev
Browse files

Fix an infinite loop in TextureView implementation 

There is a possibilty for an infinite loop in TextureView
logic, which could dequeue forever buffers without ever
drawing anything. This could happen on devices without
EGL_ANDROID_native_fence_sync extension and for frames
that consume a lot of GPU time.

Test: Passed CTS. Ran a specific sequence of frames,
Test: that used to triggers an infinite loop.
Bug: 159921224
Change-Id: I1896e21f0d87fa2fa66bac53df4265a1018f0f61
parent 487496c4

libs/nativedisplay/surfacetexture/ImageConsumer.cpp

+8 −1
Original line number Diff line number Diff line
@@ -51,7 +51,15 @@ sp<GraphicBuffer> ImageConsumer::dequeueBuffer(int* outSlotid, android_dataspace 
    }



    int slot = item.mSlot;

    *outQueueEmpty = false;

    if (item.mFence->isValid()) {

        // If fence is not signaled, that means frame is not ready and

        // outQueueEmpty is set to true. By the time the fence is signaled,

        // there may be a new buffer queued. This is a proper detection for an

        // empty queue and it is needed to avoid infinite loop in

        // ASurfaceTexture_dequeueBuffer (see b/159921224).

        *outQueueEmpty = item.mFence->getStatus() == Fence::Status::Unsignaled;



        // Wait on the producer fence for the buffer to be ready.

        err = fenceWait(item.mFence->get(), fencePassThroughHandle);

        if (err != OK) {
@@ -112,7 +120,6 @@ sp<GraphicBuffer> ImageConsumer::dequeueBuffer(int* outSlotid, android_dataspace 
    st.mCurrentFrameNumber = item.mFrameNumber;

    st.computeCurrentTransformMatrixLocked();



    *outQueueEmpty = false;

    *outDataspace = item.mDataSpace;

    *outSlotid = slot;

    return st.mSlots[slot].mGraphicBuffer;