netdev - [PATCH net] neighbour: allow NUD_NOARP entries to be forced GCed

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Message-Id: <20210607173530.46493-1-dsahern@kernel.org>
Date:   Mon,  7 Jun 2021 11:35:30 -0600
From:   David Ahern <dsahern@...nel.org>
To:     netdev@...r.kernel.org, kuba@...nel.org, davem@...emloft.net
Cc:     David Ahern <dsahern@...nel.org>,
        Kasper Dupont <kasperd@...wv.06.feb.2021.kasperd.net>,
        Thadeu Lima de Souza Cascardo <cascardo@...onical.com>
Subject: [PATCH net] neighbour: allow NUD_NOARP entries to be forced GCed

IFF_POINTOPOINT interfaces use NUD_NOARP entries for IPv6. It's possible to
fill up the neighbour table with enough entries that it will overflow for
valid connections after that.

This behaviour is more prevalent after commit 58956317c8de ("neighbor:
Improve garbage collection") is applied, as it prevents removal from
entries that are not NUD_FAILED, unless they are more than 5s old.

Fixes: 58956317c8de (neighbor: Improve garbage collection)
Reported-by: Kasper Dupont <kasperd@...wv.06.feb.2021.kasperd.net>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@...onical.com>
Signed-off-by: David Ahern <dsahern@...nel.org>
---
rebased to net tree

 net/core/neighbour.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 98f20efbfadf..bf774575ad71 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -238,6 +238,7 @@ static int neigh_forced_gc(struct neigh_table *tbl)
 
 			write_lock(&n->lock);
 			if ((n->nud_state == NUD_FAILED) ||
+			    (n->nud_state == NUD_NOARP) ||
 			    (tbl->is_multicast &&
 			     tbl->is_multicast(n->primary_key)) ||
 			    time_after(tref, n->updated))
-- 
2.24.3 (Apple Git-128)