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net: bridge: add support for sticky fdb entries
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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.

Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Nikolay Aleksandrov authored and David S. Miller committed Sep 13, 2018
1 parent 1566534 commit 435f2e7
Showing 3 changed files with 18 additions and 3 deletions.
1 change: 1 addition & 0 deletions include/uapi/linux/neighbour.h
Original file line number Diff line number Diff line change
@@ -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

/*
19 changes: 16 additions & 3 deletions net/bridge/br_fdb.c
Original file line number Diff line number Diff line change
@@ -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;
@@ -772,8 +774,10 @@ 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 ndm_flags)
{
u8 is_sticky = !!(ndm_flags & NTF_STICKY);
struct net_bridge_fdb_entry *fdb;
bool modified = false;

@@ -789,6 +793,9 @@ static int fdb_add_entry(struct net_bridge *br, struct net_bridge_port *source,
return -EINVAL;
}

if (is_sticky && (state & NUD_PERMANENT))
return -EINVAL;

fdb = br_fdb_find(br, addr, vid);
if (fdb == NULL) {
if (!(flags & NLM_F_CREATE))
@@ -832,6 +839,12 @@ static int fdb_add_entry(struct net_bridge *br, struct net_bridge_port *source,

modified = true;
}

if (is_sticky != fdb->is_sticky) {
fdb->is_sticky = is_sticky;
modified = true;
}

fdb->added_by_user = 1;

fdb->used = jiffies;
@@ -865,7 +878,7 @@ static int __br_fdb_add(struct ndmsg *ndm, struct net_bridge *br,
} else {
spin_lock_bh(&br->hash_lock);
err = fdb_add_entry(br, p, addr, ndm->ndm_state,
nlh_flags, vid);
nlh_flags, vid, ndm->ndm_flags);
spin_unlock_bh(&br->hash_lock);
}

1 change: 1 addition & 0 deletions net/bridge/br_private.h
Original file line number Diff line number Diff line change
@@ -181,6 +181,7 @@ struct net_bridge_fdb_entry {
struct hlist_node fdb_node;
unsigned char is_local:1,
is_static:1,
is_sticky:1,
added_by_user:1,
added_by_external_learn:1,
offloaded:1;

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