Paolo Abeni <pabeni(a)redhat.com> wrote:
> -static inline bool mptcp_skb_ext_exist(const struct sk_buff *skb)
> +/* move the skb extension owership, with the assumption that 'to' is
> + * newly allocated and 'from' carries only MPTCP ext
> + */
> +static inline void mptcp_skb_ext_move(struct sk_buff *to,
> +				      struct sk_buff *from)
> +{
> +	if (WARN_ON_ONCE(to->active_extensions))
> +		skb_ext_put(to);
> +	WARN_ON_ONCE(from->active_extensions & ~(1 << SKB_EXT_MPTCP));

This warn is triggered for skb that came in via a bridge.
I do not think you need the 2nd WARN.

> +	to->active_extensions = from->active_extensions;
> +	to->extensions = from->extensions;
> +	from->extensions = NULL;

This NULL assignment isn't needed -- if it is, something else is broken.

Rest looks good -- I agree that sk_is_mptcp() check could
be used as you pointed out in your reply to Christoph.

Thanks for working on this.