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neighbour: Skip default parms when resumed in neightbl_dump_info().

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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.

Also, nidx must be cleared at the end of each table loop;
otherwise, if neightbl_fill_info() for a subsequent table
fails, the leftover nidx from the previous table would be
saved in cb->args[1], resulting in erroneously skipping parms
of the subsequent table in the next dump.

Fixes: c7fb64db00 ("[NETLINK]: Neighbour table configuration and statistics via rtnetlink")
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20260909233143.2401847-5-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Kuniyuki Iwashima 2026-09-09 23:31:26 +00:00 committed by Jakub Kicinski
parent 7b430fcfc9
commit 979aabdad8
1 changed files with 8 additions and 3 deletions
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11
net/core/neighbour.c
View File

@ -2587,9 +2587,10 @@ static int neightbl_dump_info(struct sk_buff *skb, struct netlink_callback *cb)
{ {
const struct nlmsghdr *nlh = cb->nlh; const struct nlmsghdr *nlh = cb->nlh;
struct net *net = sock_net(skb->sk); 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 family, tidx, nidx = 0;
int tbl_skip = cb->args[0]; int tbl_skip = cb->args[0];
int neigh_skip = cb->args[1];
struct neigh_table *tbl; struct neigh_table *tbl;
if (cb->strict_check) { 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)) if (tidx < tbl_skip || (family && tbl->family != family))
continue; 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, nlh->nlmsg_seq, RTM_NEWNEIGHTBL,
NLM_F_MULTI) < 0) NLM_F_MULTI) < 0)
break; break;
nidx = 0; default_skip = 1;
list_for_each_entry_rcu(p, &tbl->parms_list, list) { list_for_each_entry_rcu(p, &tbl->parms_list, list) {
if (!net_eq(neigh_parms_net(p), net)) 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; neigh_skip = 0;
nidx = 0;
default_skip = 0;
} }
out: out:
rcu_read_unlock(); rcu_read_unlock();
cb->args[0] = tidx; cb->args[0] = tidx;
cb->args[1] = nidx; cb->args[1] = nidx;
cb->args[2] = default_skip;
return skb->len; return skb->len;
} }