how-to-disable-hash.diff

--- ../linux-4.3/net/core/flow_dissector.c 2018-05-16 03:08:45.000000000 -0500
+++ ./net/core/flow_dissector.c 2018-09-15 22:13:09.210965719 -0500
//disable the hash function based on IP address or port number
@@ -162,6 +162,13 @@
  case htons(ETH_P_IP): {
   const struct iphdr *iph;
   struct iphdr _iph;
+
+        //iph->ihl
+        //首部长度(4位):首部长度指的是IP层头部占32 bit字的数目
+        //(也就是IP层头部包含多少个4字节 -- 32位),包括任何选项。
+        //由于它是一个4比特字段,因此首部最长为60个字节。普通IP
+        //数据报(没有任何选择项)字段的值是5 <==> 5 * 32 / 8 = 5 * 4 = 20 Bytes
+
 ip:
   iph = __skb_header_pointer(skb, nhoff, sizeof(_iph), data, hlen, &_iph);
   if (!iph || iph->ihl < 5)
@@ -178,6 +185,18 @@

    memcpy(&key_addrs->v4addrs, &iph->saddr,
           sizeof(key_addrs->v4addrs));
+
+            //add by Kun
+            /*
+             * v4addrs is
+             * struct flow_dissector_key_ipv4_addrs {
+             *   __be32 src;
+             *   __be32 dst;
+             *  };
+             */
+            key_addrs->v4addrs->src = 0;
+            key_addrs->v4addrs->dst = 0;
+            //
    key_control->addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
   }

@@ -545,6 +564,16 @@
             target_container);
   key_ports->ports = __skb_flow_get_ports(skb, nhoff, ip_proto,
        data, hlen);
+        //add by Kun
+        /*
+         * __be32 ports: __be16 src + __be16 dst
+         */
+        //u16 a = key_ports->ports & 0xFFFF;
+        //u16 b = key_ports->ports >>16;
+        //printk("port before:%u %u\n", (unsigned int)ntohs(a), (unsigned int)ntohs(b));
+        key_ports->ports = 0;
+        //printk("port after :%u\n", key_ports->ports);
+
  }