Function cusparseSpMV_bufferSize 

pub unsafe extern "C" fn cusparseSpMV_bufferSize(
    handle: cusparseHandle_t,
    opA: cusparseOperation_t,
    alpha: *const c_void,
    matA: cusparseConstSpMatDescr_t,
    vecX: cusparseConstDnVecDescr_t,
    beta: *const c_void,
    vecY: cusparseDnVecDescr_t,
    computeType: cudaDataType,
    alg: cusparseSpMVAlg_t,
    bufferSize: *mut size_t,
) -> cusparseStatus_t