taglinefilesource code
link354include/linux/skbuff.hstruct sk_buff  * volatile link3;  /* Link for IP protocol level buffer chains   */
link3699net/core/skbuff.cskb->prev = skb->next = skb->link3 = NULL;
link3781net/core/skbuff.cn->next = n->prev = n->link3 = NULL;
link3822net/core/skbuff.cn->link3=NULL;
link3363net/ipv4/af_inet.cskb2 = skb->link3;
link376net/ipv4/ip_output.cnewskb->link3=NULL;
link3441net/ipv4/ip_output.cif (skb->link3 != NULL)
link3444net/ipv4/ip_output.cskb->link3 = NULL;
link3453net/ipv4/ip_output.csk->send_tail->link3 = skb;
link3550net/ipv4/tcp_input.cskb2 = skb->link3;
link3551net/ipv4/tcp_input.cskb->link3 = NULL;
link3577net/ipv4/tcp_input.csk->send_tail->link3 = skb;
link3580net/ipv4/tcp_input.cskb->link3 = NULL;
link3763net/ipv4/tcp_input.cif (sk->send_head->link3 &&
link3764net/ipv4/tcp_input.cafter(sk->send_head->end_seq, sk->send_head->link3->end_seq)) 
link3790net/ipv4/tcp_input.cif (sk->send_head->link3)  /* Any more queued retransmits? */
link3823net/ipv4/tcp_input.csk->send_head = oskb->link3;
link3485net/ipv4/tcp_output.cskb = skb->link3;