skb_append(skb_prev, skb); 
skb_append(skb_prev, skb, &lapb->write_queue); 
void lapb_requeue_frames(struct lapb_cb *lapb){        struct sk_buff *skb, *skb_prev = NULL;	/*	 * Requeue all the un-ack-ed frames on the output queue to be picked	 * up by lapb_kick called from the timer. This arrangement handles the	 * possibility of an empty output queue.	 */	while ((skb = skb_dequeue(&lapb->ack_queue)) != NULL) {		if (!skb_prev)			skb_queue_head(&lapb->write_queue, skb);		else			skb_append(skb_prev, skb);		skb_prev = skb;	}}
10457	/local/tlutelli/issta_data/temp/c/2005_temp/2005/10457/8728b834b226ffcf2c94a58530090e292af2a7bf/lapb_subr.c/buggy/net/lapb/lapb_subr.c