On Wed, May 27, 2020 at 5:17 PM David Ahern <dsah...@kernel.org> wrote:
>
> From: David Ahern <dsah...@gmail.com>
>
> Add BPF_XDP_DEVMAP attach type for use with programs associated with a
> DEVMAP entry.
>
> Allow DEVMAPs to associate a program with a device entry by adding
> a bpf_prog_fd to 'struct devmap_val'. Values read show the program
> id, so the fd and id are a union.
>
> The program associated with the fd must have type XDP with expected
> attach type BPF_XDP_DEVMAP. When a program is associated with a device
> index, the program is run on an XDP_REDIRECT and before the buffer is
> added to the per-cpu queue. At this point rxq data is still valid; the
> next patch adds tx device information allowing the prorgam to see both
> ingress and egress device indices.
>
> XDP generic is skb based and XDP programs do not work with skb's. Block
> the use case by walking maps used by a program that is to be attached
> via xdpgeneric and fail if any of them are DEVMAP / DEVMAP_HASH with
> > 4-byte values.
>
> Block attach of BPF_XDP_DEVMAP programs to devices.
>
> Signed-off-by: David Ahern <dsah...@gmail.com>
> ---
Please cc b...@vger.kernel.org in the future for patches related to BPF
in general.
> include/linux/bpf.h | 5 +++
> include/uapi/linux/bpf.h | 5 +++
> kernel/bpf/devmap.c | 79 +++++++++++++++++++++++++++++++++-
> net/core/dev.c | 18 ++++++++
> tools/include/uapi/linux/bpf.h | 5 +++
> 5 files changed, 110 insertions(+), 2 deletions(-)
>
[...]
>
> +static struct xdp_buff *dev_map_run_prog(struct net_device *dev,
> + struct xdp_buff *xdp,
> + struct bpf_prog *xdp_prog)
> +{
> + u32 act;
> +
> + act = bpf_prog_run_xdp(xdp_prog, xdp);
> + switch (act) {
> + case XDP_DROP:
> + fallthrough;
nit: I don't think fallthrough is necessary for cases like:
case XDP_DROP:
case XDP_PASS:
/* do something */
> + case XDP_PASS:
> + break;
> + default:
> + bpf_warn_invalid_xdp_action(act);
> + fallthrough;
> + case XDP_ABORTED:
> + trace_xdp_exception(dev, xdp_prog, act);
> + act = XDP_DROP;
> + break;
> + }
> +
> + if (act == XDP_DROP) {
> + xdp_return_buff(xdp);
> + xdp = NULL;
hm.. if you move XDP_DROP case to after XDP_ABORTED and do fallthrough
from XDP_ABORTED, you won't even need to override act and it will just
handle all the cases, no?
switch (act) {
case XDP_PASS:
return xdp;
default:
bpf_warn_invalid_xdp_action(act);
fallthrough;
case XDP_ABORTED:
trace_xdp_exception(dev, xdp_prog, act);
fallthrough;
case XDP_DROP:
xdp_return_buff(xdp);
return NULL;
}
Wouldn't this be simpler?
> + }
> +
> + return xdp;
> +}
> +
[...]
