[ovs-dev] [PATCH] netdev-offload-tc: Add drop action support.

[Simon Horman]

On Tue, Jun 30, 2020 at 08:30:45AM -0700, William Tu wrote:
> Currently drop action is not offloaded when using userspace datapath
> with tc offload.  The patch programs tc gact (generic action) chain
> ID 0 to drop the packet by setting it to TC_ACT_SHOT.
> 
> Example:
> $ ovs-appctl dpctl/add-flow netdev at ovs-netdev \
>   'recirc_id(0),in_port(2),eth(),eth_type(0x0806),\
>   arp(op=2,tha=00:50:56:e1:4b:ab,tip=10.255.1.116)' drop
> 
> $ tc filter show dev ovs-p0 ingress
> filter protocol arp pref 2 flower chain 0
> filter protocol arp pref 2 flower chain 0 handle 0x1
>   eth_type arp
>   arp_tip 10.255.1.116
>   arp_op reply
>   arp_tha 00:50:56:e1:4b:ab
>   skip_hw
>   not_in_hw
> 	action order 1: gact action drop
>     ...
> 
> Signed-off-by: William Tu <u9012063 at gmail.com>

Hi William,

this change looks good to me other than that I'm unsure
why we need #ifndef __KERNEL__.

> ---
>  lib/netdev-offload-tc.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/lib/netdev-offload-tc.c b/lib/netdev-offload-tc.c
> index 258d31f54b08..8c6bcc0aa2c7 100644
> --- a/lib/netdev-offload-tc.c
> +++ b/lib/netdev-offload-tc.c
> @@ -1788,6 +1788,12 @@ netdev_tc_flow_put(struct netdev *netdev, struct match *match,
>              action->chain = nl_attr_get_u32(nla);
>              flower.action_count++;
>              recirc_act = true;
> +#ifndef __KERNEL__
> +        } else if (nl_attr_type(nla) == OVS_ACTION_ATTR_DROP) {
> +            action->type = TC_ACT_GOTO;
> +            action->chain = 0;  /* 0 is reserved and not used by recirc. */
> +            flower.action_count++;
> +#endif
>          } else {
>              VLOG_DBG_RL(&rl, "unsupported put action type: %d",
>                          nl_attr_type(nla));
> -- 
> 2.7.4
>