* David S. Miller <[EMAIL PROTECTED]> 2005-07-25 15:56
> From: Thomas Graf <[EMAIL PROTECTED]>
> Date: Tue, 26 Jul 2005 00:35:05 +0200
>
> > We can also use ifindex and hold a reference. We won't access input_dev
> > too often so a __dev_get_by_ifindex() won't be too expensive given the
> > number of interfaces is not too big but that's another issue.
>
> Since the reference is very local in each instance we actually use it,
> we can elide the refcounting overhead most of the time perhaps.
Not sure but as I see it:
in netif_receive_skb():
if (!skb->input_dev) {
dev_hold(skb->dev);
skb->input_dev = skb->dev->ifindex;
}
in __kfree_skb():
if (skb->input_dev)
dev_put(__dev_get_by_index(skb->input_dev));
in mirred:
if (skb2->input_dev)
dev_put(__dev_get_by_index(skb2->input_dev));
dev_hold(skb->dev);
skb2->input_dev = skb2->dev->ifindex;
in skb_clone()
...
The __dev_get_by_index() can be expensive with
more than a 1k interfaces but the hash generally
does well so I don't see much of a problem.
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