taglinefilesource code
send_tail191include/net/sock.hstruct sk_buff    * volatile send_tail;
send_tail448net/ipv4/ip_output.csk->send_tail = skb;
send_tail453net/ipv4/ip_output.csk->send_tail->link3 = skb;
send_tail454net/ipv4/ip_output.csk->send_tail = skb;
send_tail396net/ipv4/tcp_input.cnewsk->send_tail = NULL;
send_tail537net/ipv4/tcp_input.csk->send_tail = NULL;
send_tail570net/ipv4/tcp_input.csk->send_tail = skb;
send_tail574net/ipv4/tcp_input.csk->send_tail->link3 = skb;
send_tail575net/ipv4/tcp_input.csk->send_tail = skb;
send_tail662net/ipv4/tcp_input.cif (sk->send_tail == NULL || sk->send_head == NULL) 
send_tail665net/ipv4/tcp_input.csk->send_tail = NULL;
send_tail823net/ipv4/tcp_input.csk->send_tail = NULL;