!6533 Fix code warning

Merge pull request !6533 from ZPaC/master-fix-code-warning

mindspore/ccsrc/ps/util.cc

@@ -122,6 +122,9 @@ int Util::LocalShard(int first_dim, int rank_id, int server_num) {
 }
 
 std::map<int, int> Util::AllRankLocalShard(int first_dim, int rank_id, int server_num) {
+  if (first_dim <= 0 || server_num <= 0 || rank_id < 0) {
+    MS_LOG(EXCEPTION) << "Input values are invalid.";
+  }
   if (rank_id >= server_num) {
     MS_LOG(EXCEPTION) << "The rank ID " << rank_id << " should be less than the number of servers " << server_num;
   }

mindspore/ccsrc/ps/worker_proxy.h

@@ -548,8 +548,8 @@ void WorkerProxy<T>::PrepareSparseGradient(const size_t begin, const size_t end,
   int offset = 0;
   int index = 0;
   size_t segment_data_size = segment_size * sizeof(T);
-  size_t dst_size = 0;
-  size_t src_size = 0;
+  size_t dst_size;
+  size_t src_size;
   void *dst_data = nullptr;
   void *src_data = nullptr;
   for (auto &pair : indice_to_grads) {