From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH 1/5] netpoll: use sk_buff_head for txq
Date: Mon, 23 Oct 2006 23:03:50 -0700 (PDT)
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From: Stephen Hemminger <shemminger@osdl.org>
Date: Mon, 23 Oct 2006 12:02:53 -0700

> +	spin_lock_irqsave(&netpoll_txq.lock, flags);
> +	for (skb = (struct sk_buff *)netpoll_txq.next;
> +	     skb != (struct sk_buff *)&netpoll_txq; skb = next) {
> +		next = skb->next;
> +		if (skb->dev == dev) {
> +			skb_unlink(skb, &netpoll_txq);
> +			kfree_skb(skb);
> +		}
>  	}
> +	spin_unlock_irqrestore(&netpoll_txq.lock, flags);

IRQ's are disabled, I think we can't call kfree_skb() in such a
context.

That's why zap_completion_queue() has all of these funny
skb->destructor checks and such, all of this stuff potentially runs in
IRQ context.