Qdisc list crashed.

Does anyone meet the error that qdisc's pfifo_fast_dequeque
would crash at "next->prev = prev; " in qdisc_restart() function
because list->next->next is NULL.
I am using kernel 2.4.18 for arm. when i use dev_queue_xmit()
function to send out one skb repeatly, it crashed after serveral packet

was correctly delievered.

here is my code frag:
skb_get(skb);
if(dev_queue_xmit(skb))
TotalSent ++;