On Monday 07 April 2008 15:13:44 Herbert Xu wrote:
> Rusty Russell <rusty@xxxxxxxxxxxxxxx> wrote:
> > +/* We are done with this skb: put it in the used pile. */
> > +static void skb_finished(struct skb_shared_info *sinfo)
> > +{
> > + struct skb_shinfo_tun *sht = (void *)(sinfo + 1);
> > +
> > + /* FIXME: Race prevention */
> > + vring_used_buffer_atomic(sht->tun->outring, sht->id, sht->len);
> > + vring_wake(sht->tun->outring);
> > +
> > + /* Release device. */
> > + dev_put(sht->tun->dev);
> > +}
>
> On second thought, this is not going to work. The network stack
> can clone individual pages out of this skb and put it into a new
> skb. Therefore whatever scheme we come up with will either need
> to be page-based, or add a flag to tell the network stack that it
> can't clone those pages.
Erk... I'll put in the latter for now. A page-level solution is not really
an option: if userspace hands us mmaped pages for example.
Thanks,
Rusty.
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