Re: [PATCH net-next] net: bridge: add support for sticky fdb entries

[Stephen Hemminger <stephen@networkplumber.org>]

On Mon, 10 Sep 2018 13:16:01 +0300
Nikolay Aleksandrov <nikolay@cumulusnetworks.com> wrote:

> Add support for entries which are "sticky", i.e. will not change their port
> if they show up from a different one. A new ndm flag is introduced for that
> purpose - NTF_STICKY. We allow to set it only to non-local entries.

Is there a name for this in other network switch API's?

> 
> Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
> ---
> I'll send the selftest for sticky with the iproute2 patch if this one is
> accepted. We've had multiple requests to support such flag and now it's
> also needed for some eVPN and clag setups.
> 
>  include/uapi/linux/neighbour.h |  1 +
>  net/bridge/br_fdb.c            | 19 ++++++++++++++++---
>  net/bridge/br_private.h        |  1 +
>  3 files changed, 18 insertions(+), 3 deletions(-)
> 
> diff --git a/include/uapi/linux/neighbour.h b/include/uapi/linux/neighbour.h
> index 904db6148476..998155444e0d 100644
> --- a/include/uapi/linux/neighbour.h
> +++ b/include/uapi/linux/neighbour.h
> @@ -43,6 +43,7 @@ enum {
>  #define NTF_PROXY	0x08	/* == ATF_PUBL */
>  #define NTF_EXT_LEARNED	0x10
>  #define NTF_OFFLOADED   0x20
> +#define NTF_STICKY	0x40
>  #define NTF_ROUTER	0x80
>  
>  /*
> diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
> index 502f66349530..26569ed06a4d 100644
> --- a/net/bridge/br_fdb.c
> +++ b/net/bridge/br_fdb.c
> @@ -584,7 +584,7 @@ void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
>  			unsigned long now = jiffies;
>  
>  			/* fastpath: update of existing entry */
> -			if (unlikely(source != fdb->dst)) {
> +			if (unlikely(source != fdb->dst && !fdb->is_sticky)) {
>  				fdb->dst = source;
>  				fdb_modified = true;
>  				/* Take over HW learned entry */
> @@ -656,6 +656,8 @@ static int fdb_fill_info(struct sk_buff *skb, const struct net_bridge *br,
>  		ndm->ndm_flags |= NTF_OFFLOADED;
>  	if (fdb->added_by_external_learn)
>  		ndm->ndm_flags |= NTF_EXT_LEARNED;
> +	if (fdb->is_sticky)
> +		ndm->ndm_flags |= NTF_STICKY;
>  
>  	if (nla_put(skb, NDA_LLADDR, ETH_ALEN, &fdb->key.addr))
>  		goto nla_put_failure;
> @@ -772,7 +774,8 @@ int br_fdb_dump(struct sk_buff *skb,
>  
>  /* Update (create or replace) forwarding database entry */
>  static int fdb_add_entry(struct net_bridge *br, struct net_bridge_port *source,
> -			 const __u8 *addr, __u16 state, __u16 flags, __u16 vid)
> +			 const u8 *addr, u16 state, u16 flags, u16 vid,
> +			 u8 is_sticky)

Why not change the API to take a full ndm flags, someone is sure to add more later.