[Question] the precondition of calling alloc_skb()/kfree_skb()?

Hi, all:

I encountered a problem of using sk_buff.

I used 2.4.20 kernel, when burst traffic come, the kernel will complain
a bug report at skbuff.c:316 later:

311 void __kfree_skb(struct sk_buff *skb)
312 {
313 if (skb->list) {
314 printk(KERN_WARNING "Warning: kfree_skb passed an skb still "
315 "on a list (from %p).\n", NET_CALLER(skb));
316 BUG(); /* HERE!!! */
317 }
/* snip some code here */
332 }


I saw the dev_kfree_skb_irq() and dev_kfree_skb_irq(), and how to use
them. even, in fact, we work in pure poll I/O model, so the NIC can not
issue any interrupt.

And, I searched google, there are many similar reports like above, but
almost of them have no reply. I think there may have some unknown thing
while sk_buff API.

Well, I hope know, are there some preconditions of calling alloc_skb()
or *_kfree_skb_*() ? Thank in advanced.

Good luck.

- Yu Li