Re: [PATCH net] openvswitch: Fix ovs_flow_key_update()

[Jiri Benc]

On Wed, 29 Mar 2017 17:14:10 -0700, Yi-Hung Wei wrote:
> ovs_flow_key_update() is called when the flow key is invalid, and it is
> used to update and revalidate the flow key. Commit 329f45bc4f19
> ("openvswitch: add mac_proto field to the flow key") introduces mac_proto
> field to flow key and use it to determine whether the flow key is valid.
> However, the commit does not update the code path in ovs_flow_key_update()
> to revalidate the flow key which may cause BUG_ON() on execute_recirc().
> This patch addresses the aforementioned issue.

Good catch.

>  int ovs_flow_key_update(struct sk_buff *skb, struct sw_flow_key *key)
>  {
> +     int res;
> +
> +     res = key_extract_mac_proto(skb);
> +     if (res < 0)
> +             return res;
> +     key->mac_proto = res;
> +
>       return key_extract(skb, key);
>  }

But this should just reset the SW_FLOW_KEY_INVALID flag, there's no
need to recompute mac_proto.

Something like this:

 int ovs_flow_key_update(struct sk_buff *skb, struct sw_flow_key *key)
 {
-       return key_extract(skb, key);
+       int res;
+
+       res = key_extract(skb, key);
+       if (!res)
+               key->mac_proto &= ~SW_FLOW_KEY_INVALID;
+       return res;
 }

Thanks,

 Jiri