Violation access with cl_event from GLsync usage

Hi,

Using R9 290X with Catalyst 14.12 on Windows 8.1 I'm trying to use OpenCL for TressFX simulation :

YAGF/tfx-ocl.cpp at master · vlj/YAGF · GitHub

The relevant part of the code is :

  int err = CL_SUCCESS;

  cl_event ev = 0;

  if (syncFirstPassRenderComplete);

    ev = clCreateEventFromGLsyncKHRCustom(context, syncFirstPassRenderComplete, &err);

  // First pass is done so sim is done too, can safely upload

  err = clEnqueueWriteBuffer(queue, ConstantSimBuffer, CL_FALSE, 0, sizeof(struct SimulationConstants), &cbuf, 0, 0, 0);

  err = clEnqueueAcquireGLObjects(queue, 1, &PosBuffer, 0, 0, 0);

  err = clSetKernelArg(kernel, 0, sizeof(cl_mem), &PosBuffer);

  err = clSetKernelArg(kernel, 1, sizeof(cl_mem), &PreviousPos);

  err = clSetKernelArg(kernel, 2, sizeof(cl_mem), &StrandType);

  err = clSetKernelArg(kernel, 3, sizeof(cl_mem), &InitialPos);

  err = clSetKernelArg(kernel, 4, sizeof(cl_mem), &ConstantSimBuffer);

  size_t local_wg = 64;

  size_t global_wg = .5 * tfxassets.m_NumTotalHairVertices;

  err = clEnqueueNDRangeKernel(queue, kernel, 1, 0, &global_wg, &local_wg, 0, 0, 0);

  err = clEnqueueReleaseGLObjects(queue, 1, &PosBuffer, 0, 0, 0);

  clFinish(queue);

  if (syncFirstPassRenderComplete);

  {

    glDeleteSync(syncFirstPassRenderComplete);

    clReleaseEvent(ev);

  }

  return;

I'm attempting to use explicit sync between cl and GL using  clCreateEventFromGLsyncKHR by replacing

  err = clEnqueueWriteBuffer(queue, ConstantSimBuffer, CL_FALSE, 0, sizeof(struct SimulationConstants), &cbuf, 0, 0, 0);

by

  if (ev)

    err = clEnqueueWriteBuffer(queue, ConstantSimBuffer, CL_FALSE, 0, sizeof(struct SimulationConstants), &cbuf, 1, &ev, 0);

  else

    err = clEnqueueWriteBuffer(queue, ConstantSimBuffer, CL_FALSE, 0, sizeof(struct SimulationConstants), &cbuf, 0, 0, 0);

ie I'm adding a sync between last GL command that uses PosBuffer and before first opencl command so that some opencl upload/kernel can be executed while the second OpenGL fragment shader is in flight.

It works however after a couple of frame there is a crash in atigktxx.dll (Access violation reading location 0xFEEEFEEE.). I get no OpenCL or OpenGL error.

I'm not sure what's happening since I delete sync and clean cl_event after cl_finish. I tested with an event generated from an opencl call each frame and it works, I suspect the issue only happens with cl_event generated from GL sync object.