[portsorch]: Add set port MTU function (sonic-net#218)

* Add set port MTU function
* Add L2 header length to the MTU on hardware

Author: andriymoroz-mlnx

orchagent/portsorch.cpp

@@ -5,6 +5,7 @@
 #include <sstream>
 #include <set>
 
+#include <netinet/if_ether.h>
 #include "net/if.h"
 
 #include "logger.h"
@@ -223,6 +224,25 @@ bool PortsOrch::setPortAdminStatus(sai_object_id_t id, bool up)
     return true;
 }
 
+bool PortsOrch::setPortMtu(sai_object_id_t id, sai_uint32_t mtu)
+{
+    SWSS_LOG_ENTER();
+
+    sai_attribute_t attr;
+    attr.id = SAI_PORT_ATTR_MTU;
+    /* mtu + 14 + 4 + 4 = 22 bytes */
+    attr.value.u32 = mtu + sizeof(struct ether_header) + FCS_LEN + VLAN_TAG_LEN;
+
+    sai_status_t status = sai_port_api->set_port_attribute(id, &attr);
+    if (status != SAI_STATUS_SUCCESS)
+    {
+        SWSS_LOG_ERROR("Failed to set MTU %u to port pid:%lx", attr.value.u32, id);
+        return false;
+    }
+    SWSS_LOG_INFO("Set MTU %u to port pid:%lx", attr.value.u32, id);
+    return true;
+}
+
 bool PortsOrch::setHostIntfsOperStatus(sai_object_id_t port_id, bool up)
 {
     SWSS_LOG_ENTER();
@@ -303,6 +323,8 @@ void PortsOrch::doPortTask(Consumer &consumer)
         {
             set<int> lane_set;
             string admin_status;
+            uint32_t mtu = 0;
+
             for (auto i : kfvFieldsValues(t))
             {
                 /* Get lane information of a physical port and initialize the port */
@@ -322,6 +344,10 @@ void PortsOrch::doPortTask(Consumer &consumer)
                 /* Set port admin status */
                 if (fvField(i) == "admin_status")
                     admin_status = fvValue(i);
+
+                /* Set port mtu */
+                if (fvField(i) == "mtu")
+                    mtu = stoul(fvValue(i));
             }
 
             if (lane_set.size())
@@ -385,6 +411,24 @@ void PortsOrch::doPortTask(Consumer &consumer)
                 else
                     SWSS_LOG_ERROR("Failed to get port id by alias:%s", alias.c_str());
             }
+
+            if (mtu != 0)
+            {
+                Port p;
+                if (getPort(alias, p))
+                {
+                    if (setPortMtu(p.m_port_id, mtu))
+                        SWSS_LOG_NOTICE("Set port %s MTU to %u", alias.c_str(), mtu);
+                    else
+                    {
+                        SWSS_LOG_ERROR("Failed to set port %s MTU to %u", alias.c_str(), mtu);
+                        it++;
+                        continue;
+                    }
+                }
+                else
+                    SWSS_LOG_ERROR("Failed to get port id by alias:%s", alias.c_str());
+            }
         }
         else
             SWSS_LOG_ERROR("Unknown operation type %s", op.c_str());

orchagent/portsorch.h

@@ -9,6 +9,9 @@
 
 #include <map>
 
+#define FCS_LEN 4
+#define VLAN_TAG_LEN 4
+
 static const map<sai_port_oper_status_t, string> oper_status_strings =
 {
     { SAI_PORT_OPER_STATUS_UNKNOWN,     "unknown" },
@@ -80,6 +83,7 @@ class PortsOrch : public Orch, public Subject
     bool removeLagMember(Port lag, Port port);
 
     bool setPortAdminStatus(sai_object_id_t id, bool up);
+    bool setPortMtu(sai_object_id_t id, sai_uint32_t mtu);
 };
 #endif /* SWSS_PORTSORCH_H */