Messages in this thread |  | | Date | Sat, 05 Apr 2008 12:26:57 -0500 | From | Anthony Liguori <> | Subject | Re: [PATCH RFC 3/5] tun: vringfd receive support. |
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Rusty Russell wrote: > This patch modifies tun to allow a vringfd to specify the receive > buffer. Because we can't copy to userspace in bh context, we queue > like normal then use the "pull" hook to actually do the copy. > > More thought needs to be put into the possible races with ring > registration and a simultaneous close, for example (see FIXME). > > We use struct virtio_net_hdr prepended to packets in the ring to allow > userspace to receive GSO packets in future (at the moment, the tun > driver doesn't tell the stack it can handle them, so these cases are > never taken). > > Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
<snip>
> + > +#ifdef CONFIG_VRINGFD
I think the rest of the code needs these for it to actually work without VRINGFD.
> +static void unset_recv(void *_tun) > +{ > + struct tun_struct *tun = _tun; > + > + tun->inring = NULL; > +} > + > +/* Returns number of used buffers, or negative errno. */ > +static int pull_recv_skbs(void *_tun) > +{ > + struct tun_struct *tun = _tun; > + int err = 0, num_copied = 0; > + struct sk_buff *skb; > + > + while ((skb = skb_dequeue(&tun->readq)) != NULL) { > + struct iovec iov[1+MAX_SKB_FRAGS]; > + struct virtio_net_hdr gso = { 0 }; /* no info leak */ > + unsigned int iovnum = ARRAY_SIZE(iov); > + unsigned long len; > + int id; > + > + id = vring_get_buffer(tun->inring, iov, &iovnum, &len, > + NULL, NULL, NULL); > + if (id <= 0) { > + err = id; > + break; > + }
Ah, I see now why you're passing something from the stack.
Regards,
Anthony Liguori
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