[PATCH v2 net 4/4] neighbour: Skip default parms when resumed in neightbl_dump_info().
From: Kuniyuki Iwashima <kuniyu@google.com>
Date: 2026-09-08 21:14:25
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
neightbl_dump_info() calls neightbl_fill_info() in each loop
to render the default parms.
If there are many devices and neightbl_fill_param_info() failed,
neightbl_fill_info() is called again when the dump resumes:
# ynl --family rt-neigh --dump getneightbl --output-json |
jq '.[] | {name: .name, ifindex: .parms.ifindex}'
...
{
"name": "ndisc_cache",
"ifindex": null
}
...
{
"name": "ndisc_cache",
"ifindex": 6
}
{
"name": "ndisc_cache",
"ifindex": null
}
{
"name": "ndisc_cache",
"ifindex": 5
}
Let's skip neightbl_fill_info() if it is already called in
neightbl_dump_info().
Note that we cannot use !neigh_skip instead of !default_skip
because default_skip == 1 && neigh_skip == 0 could be true
if the first neightbl_fill_param_info() fails.
Fixes: c7fb64db001f ("[NETLINK]: Neighbour table configuration and statistics via rtnetlink")
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
---
Cc: Thomas Graf <tgraf@suug.ch>
---
net/core/neighbour.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 02bf940ce00a..7448320f7ad5 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c@@ -2587,9 +2587,10 @@ static int neightbl_dump_info(struct sk_buff *skb, struct netlink_callback *cb) { const struct nlmsghdr *nlh = cb->nlh; struct net *net = sock_net(skb->sk); + int default_skip = cb->args[2]; + int neigh_skip = cb->args[1]; int family, tidx, nidx = 0; int tbl_skip = cb->args[0]; - int neigh_skip = cb->args[1]; struct neigh_table *tbl; if (cb->strict_check) {
@@ -2613,12 +2614,13 @@ static int neightbl_dump_info(struct sk_buff *skb, struct netlink_callback *cb) if (tidx < tbl_skip || (family && tbl->family != family)) continue; - if (neightbl_fill_info(skb, tbl, NETLINK_CB(cb->skb).portid, + if (!default_skip && + neightbl_fill_info(skb, tbl, NETLINK_CB(cb->skb).portid, nlh->nlmsg_seq, RTM_NEWNEIGHTBL, NLM_F_MULTI) < 0) break; - nidx = 0; + default_skip = 1; list_for_each_entry_rcu(p, &tbl->parms_list, list) { if (!net_eq(neigh_parms_net(p), net))
@@ -2641,12 +2643,15 @@ static int neightbl_dump_info(struct sk_buff *skb, struct netlink_callback *cb) } neigh_skip = 0; + nidx = 0; + default_skip = 0; } out: rcu_read_unlock(); cb->args[0] = tidx; cb->args[1] = nidx; + cb->args[2] = default_skip; return skb->len; }
--
2.55.0.979.g7e5102b832-goog