On Thu, 7 Apr 2016 21:48:47 -0700 Brenden Blanco <bbla...@plumgrid.com> wrote:
> Add two new set/get netdev ops for drivers implementing the
> BPF_PROG_TYPE_PHYS_DEV filter.
>
> Signed-off-by: Brenden Blanco <bbla...@plumgrid.com>
[...]
>
> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> index cb4e508..3acf732 100644
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
[...]
> @@ -1102,6 +1103,14 @@ struct tc_to_netdev {
> * appropriate rx headroom value allows avoiding skb head copy on
> * forward. Setting a negative value resets the rx headroom to the
> * default value.
> + * int (*ndo_bpf_set)(struct net_device *dev, struct bpf_prog *prog);
> + * This function is used to set or clear a bpf program used in the
> + * earliest stages of packet rx. The prog will have been loaded as
> + * BPF_PROG_TYPE_PHYS_DEV. The callee is responsible for calling
> + * bpf_prog_put on any old progs that are stored, but not on the passed
> + * in prog.
> + * bool (*ndo_bpf_get)(struct net_device *dev);
> + * This function is used to check if a bpf program is set on the device.
> *
This interface for the entire device, right. I can imagine that users
want to attach a eBPF program per RX queue. Can we adapt the interface
to support this? (could default to adding it all queues)
I'm also wondering if we should add a "flags" parameter. Or maybe we
can extend 'struct bpf_prog' with I have in mind.
When the eBPF program is attached to a RX queue, I want to know if the
program want to modify packet-data, up-front.
The problem is that most drivers use dma_sync, which means that data is
considered 'read-only' (the "considered" part depend on DMA engine, and
we might find a DMA loop-hole for some configs).
If the program want to write, the driver have the option of
reconfiguring the driver routine to use dma_unmap, before handing over
the page. Or driver can also choose to realloc the specific RX ring
queue pages as single pages (using dma_map/unmap consistently).
This also allow us to give a return code indicating given driver does
not support writable packet-pages (rejecting program).
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
Author of http://www.iptv-analyzer.org
LinkedIn: http://www.linkedin.com/in/brouer
