Re: [PATCH 1/5] netpoll: use sk_buff_head for txq

From: Stephen Hemminger
Date: Tue Oct 24 2006 - 10:51:59 EST


On Mon, 23 Oct 2006 23:03:50 -0700 (PDT)
David Miller <davem@xxxxxxxxxxxxx> wrote:

> From: Stephen Hemminger <shemminger@xxxxxxxx>
> 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.

It is save since the skb's only come from this code (no destructors).

>
> 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.

It should use __kfree_skb in the purge routine (like other places).
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