taglinefilesource code
send_tail104include/net/sock.hstruct sk_buff    * volatile send_tail;
send_tail674net/ipv4/af_inet.csk->send_tail = NULL;
send_tail1825net/ipv4/ip.csk->send_tail = skb;
send_tail1830net/ipv4/ip.csk->send_tail->link3 = skb;
send_tail1831net/ipv4/ip.csk->send_tail = skb;
send_tail2698net/ipv4/tcp.cnewsk->send_tail = NULL;
send_tail3167net/ipv4/tcp.csk->send_tail = NULL;
send_tail3204net/ipv4/tcp.csk->send_tail = skb;
send_tail3208net/ipv4/tcp.csk->send_tail->link3 = skb;
send_tail3209net/ipv4/tcp.csk->send_tail = skb;
send_tail3221net/ipv4/tcp.cif (sk->send_tail == NULL || sk->send_head == NULL) 
send_tail3224net/ipv4/tcp.csk->send_tail = NULL;
send_tail3415net/ipv4/tcp.csk->send_tail = NULL;