Hangbin Liu <liuhangbin@xxxxxxxxx> writes:
> This patch adds two flags BPF_F_BROADCAST and BPF_F_EXCLUDE_INGRESS to
> extend xdp_redirect_map for broadcast support.
>
> With BPF_F_BROADCAST the packet will be broadcasted to all the interfaces
> in the map. with BPF_F_EXCLUDE_INGRESS the ingress interface will be
> excluded when do broadcasting.
>
> When getting the devices in dev hash map via dev_map_hash_get_next_key(),
> there is a possibility that we fall back to the first key when a device
> was removed. This will duplicate packets on some interfaces. So just walk
> the whole buckets to avoid this issue. For dev array map, we also walk the
> whole map to find valid interfaces.
>
> Function bpf_clear_redirect_map() was removed in
> commit ee75aef23afe ("bpf, xdp: Restructure redirect actions").
> Add it back as we need to use ri->map again.
>
> Here is the performance result by using 10Gb i40e NIC, do XDP_DROP on
> veth peer, run xdp_redirect_{map, map_multi} in sample/bpf and send pkts
> via pktgen cmd:
> ./pktgen_sample03_burst_single_flow.sh -i eno1 -d $dst_ip -m $dst_mac -t 10 -s 64
>
> There are some drop back as we need to loop the map and get each interface.
>
> Version | Test | Generic | Native
> 5.12 rc4 | redirect_map i40e->i40e | 1.9M | 9.6M
> 5.12 rc4 | redirect_map i40e->veth | 1.7M | 11.7M
> 5.12 rc4 + patch | redirect_map i40e->i40e | 1.9M | 9.3M
> 5.12 rc4 + patch | redirect_map i40e->veth | 1.7M | 11.4M
> 5.12 rc4 + patch | redirect_map multi i40e->i40e | 1.9M | 8.9M
> 5.12 rc4 + patch | redirect_map multi i40e->veth | 1.7M | 10.9M
> 5.12 rc4 + patch | redirect_map multi i40e->mlx4+veth | 1.2M | 3.8M
>
> Signed-off-by: Hangbin Liu <liuhangbin@xxxxxxxxx>
>
> ---
> v6:
> Fix a skb leak in the error path for generic XDP
That's better, thanks! When checking this I at first thought you were
missing a free; turns out I was wrong, the caller of
xdp_do_generic_redirect() will free the skb on error.
However, this is also the case for the native path: the driver is
supposed to free/recycle the frame if xdp_do_redirect() fails. Which
means that this:
[...]
> +static int dev_map_enqueue_clone(struct bpf_dtab_netdev *obj,
> + struct net_device *dev_rx,
> + struct xdp_frame *xdpf)
> +{
> + struct xdp_frame *nxdpf;
> +
> + nxdpf = xdpf_clone(xdpf);
> + if (unlikely(!nxdpf)) {
> + xdp_return_frame_rx_napi(xdpf);
> + return -ENOMEM;
> + }
is wrong; the ENOMEM return gets propagated up to the caller of
xdp_do_redirect() which will take care of freeing the frame, so this
code shouldn't also be freeing it.
Sorry for not spotting this on the last round - these error conditions
are a bit confusing to me as well. Making the generic and native paths
more similar like you did in this round made it more obvious, though,
which was the point; so yay! :)
-Toke
