Add an API `ff_get_traffic` to get traffic for QoS or other.

lib/ff_api.h

@@ -154,6 +154,11 @@ extern int ff_fdisused(int fd);
 
 extern int ff_getmaxfd(void);
 
+/* Get traffic for QoS or other via API.
+ * The size of buffer must >= siezof(struct ff_traffic_args), now is 32 bytes.
+ */
+void ff_get_traffic(void *buffer);
+
 /* route api begin */
 enum FF_ROUTE_CTL {
     FF_ROUTE_ADD,

lib/ff_api.symlist

@@ -57,3 +57,4 @@ ff_mbuf_set_vlan_info
 ff_zc_mbuf_get
 ff_zc_mbuf_write
 ff_zc_mbuf_read
+ff_get_traffic

lib/ff_dpdk_if.c

@@ -1704,6 +1704,11 @@ handle_traffic_msg(struct ff_msg *msg)
     msg->result = 0;
 }
 
+void ff_get_traffic(void *buffer)
+{
+    *(struct ff_traffic_args *)buffer = ff_traffic;
+}
+
 #ifdef FF_KNI
 static inline void
 handle_knictl_msg(struct ff_msg *msg)