Ignore ALREADY_EXIST error in FDB creation (sonic-net#1815)

What I did
Ignore ALREADY_EXIST error in FDB creation.
Fix: sonic-net/sonic-buildimage#7798

Why I did it
In FDB creation, there are scenarios where the hardware learns an FDB entry before orchagent. In such cases, the FDB SAI creation would report the status of SAI_STATUS_ITEM_ALREADY_EXISTS, and orchagent should ignore the error and treat it as entry was explicitly created.

orchagent/orch.cpp

@@ -699,15 +699,38 @@ task_process_status Orch::handleSaiCreateStatus(sai_api_t api, sai_status_t stat
  * in each orch.
  * 3. Take the type of sai api into consideration.
  */
- switch (status)
+ switch (api)
  {
- case SAI_STATUS_SUCCESS:
- SWSS_LOG_WARN("SAI_STATUS_SUCCESS is not expected in handleSaiCreateStatus");
- return task_success;
+ case SAI_API_FDB:
+ switch (status)
+ {
+ case SAI_STATUS_SUCCESS:
+ SWSS_LOG_WARN("SAI_STATUS_SUCCESS is not expected in handleSaiCreateStatus");
+ return task_success;
+ case SAI_STATUS_ITEM_ALREADY_EXISTS:
+ /*
+ * In FDB creation, there are scenarios where the hardware learns an FDB entry before orchagent.
+ * In such cases, the FDB SAI creation would report the status of SAI_STATUS_ITEM_ALREADY_EXISTS,
+ * and orchagent should ignore the error and treat it as entry was explicitly created.
+ */
+ return task_success;
+ default:
+ SWSS_LOG_ERROR("Encountered failure in create operation, exiting orchagent, SAI API: %s, status: %s",
+ sai_serialize_api(api).c_str(), sai_serialize_status(status).c_str());
+ exit(EXIT_FAILURE);
+ }
+ break;
  default:
- SWSS_LOG_ERROR("Encountered failure in create operation, exiting orchagent, SAI API: %s, status: %s",
- sai_serialize_api(api).c_str(), sai_serialize_status(status).c_str());
- exit(EXIT_FAILURE);
+ switch (status)
+ {
+ case SAI_STATUS_SUCCESS:
+ SWSS_LOG_WARN("SAI_STATUS_SUCCESS is not expected in handleSaiCreateStatus");
+ return task_success;
+ default:
+ SWSS_LOG_ERROR("Encountered failure in create operation, exiting orchagent, SAI API: %s, status: %s",
+ sai_serialize_api(api).c_str(), sai_serialize_status(status).c_str());
+ exit(EXIT_FAILURE);
+ }
  }
  return task_need_retry;
 }