Ignore removing switch for mellanox platform due to known limitation (#1216)

* Ignore removing switch for mellanox platform due to known limitation

* Fix review comment

* Fix review comment

Author: Junchao-Mellanox

configure.ac

@@ -17,6 +17,10 @@ AX_ADD_AM_MACRO_STATIC([])
 
 AM_CONDITIONAL(SONIC_ASIC_PLATFORM_BAREFOOT,   test x$CONFIGURED_PLATFORM = xbarefoot)
 AM_CONDITIONAL(SONIC_ASIC_PLATFORM_BROADCOM,   test x$CONFIGURED_PLATFORM = xbroadcom)
+AM_CONDITIONAL(SONIC_ASIC_PLATFORM_MELLANOX,   test x$CONFIGURED_PLATFORM = xmellanox)
+
+AM_COND_IF([SONIC_ASIC_PLATFORM_MELLANOX],
+        AC_DEFINE([MELLANOX], [1], [Define to 1 on Mellanox Platform]))
 
 AC_ARG_ENABLE(debug,
 [  --enable-debug          turn on debugging],

syncd/Syncd.cpp

@@ -1,3 +1,4 @@
+#include "config.h"
 #include "Syncd.h"
 #include "VidManager.h"
 #include "NotificationHandler.h"
@@ -4729,7 +4730,15 @@ void Syncd::run()
 
     m_mdioIpcServer->stopMdioThread();
 
-    sai_status_t status = removeAllSwitches();
+    sai_status_t status = SAI_STATUS_SUCCESS;
+#ifdef MELLANOX
+    if (shutdownType != SYNCD_RESTART_TYPE_COLD)
+    {
+        status = removeAllSwitches();
+    }
+#else
+    status = removeAllSwitches();
+#endif
 
     // Stop notification thread after removing switch
     m_processor->stopNotificationsProcessingThread();