[Intel MKL] Static code analysis tool fixes

- mkl_cpu_allocator.h: disallowing copy constructor and assignement operator; returning nullptr from non-void functions even though they generate Unimplemented Status code
- mkl_graph_util.h: making kTensorOrdering const because it never gets changed anyway
- mkl_layout_pass.cc: adding checks for nullptr before dereferencing

1 files changed, 5 insertions, 0 deletions

diff --git a/tensorflow/core/common_runtime/mkl_cpu_allocator.h b/tensorflow/core/common_runtime/mkl_cpu_allocator.h
index 99bd43e090..6b76e7e0e7 100644
--- a/tensorflow/core/common_runtime/mkl_cpu_allocator.h
+++ b/tensorflow/core/common_runtime/mkl_cpu_allocator.h
@@ -148,12 +148,14 @@ class MklCPUAllocator : public VisitableAllocator {
     Status s = Status(error::Code::UNIMPLEMENTED,
                       "Unimplemented case for hooking MKL function.");
     TF_CHECK_OK(s);  // way to assert with an error message
+    return nullptr; // return a value and make static code analyzers happy
   }
 
   static inline void* ReallocHook(void* ptr, size_t size) {
     Status s = Status(error::Code::UNIMPLEMENTED,
                       "Unimplemented case for hooking MKL function.");
     TF_CHECK_OK(s);  // way to assert with an error message
+    return nullptr; // return a value and make static code analyzers happy
   }
 
   /// Do we allow growth in BFC Allocator
@@ -166,6 +168,9 @@ class MklCPUAllocator : public VisitableAllocator {
   static constexpr const size_t kAlignment = 64;
 
   VisitableAllocator* allocator_;  // owned by this class
+
+  // Prevent copying and assignment
+  TF_DISALLOW_COPY_AND_ASSIGN(MklCPUAllocator);
 };
 
 }  // namespace tensorflow