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Date:   Mon, 12 Dec 2022 23:38:01 -0800
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Message-ID: <20221213073801.361500-1-decot+git@google.com>
Subject: [PATCH v1 1/1] net: neigh: persist proxy config across link flaps
From:   David Decotigny <decot+git@google.com>
To:     "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Cc:     Nikolay Aleksandrov <razor@blackwall.org>,
        David Ahern <dsahern@kernel.org>,
        "Denis V. Lunev" <den@openvz.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Chen Zhongjin <chenzhongjin@huawei.com>,
        David Decotigny <ddecotig@google.com>,
        Yuwei Wang <wangyuweihx@gmail.com>,
        Alexander Mikhalitsyn <alexander.mikhalitsyn@virtuozzo.com>,
        Thomas Zeitlhofer <thomas.zeitlhofer+lkml@ze-it.at>
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From: David Decotigny <ddecotig@google.com>

Without this patch, the 'ip neigh add proxy' config is lost when the
cable or peer disappear, ie. when the link goes down while staying
admin up. When the link comes back, the config is never recovered.

This patch makes sure that such an nd proxy config survives a switch
or cable issue.

Signed-off-by: David Decotigny <ddecotig@google.com>


---
 net/core/neighbour.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 952a54763358..5ad7ac674daa 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -426,7 +426,10 @@ static int __neigh_ifdown(struct neigh_table *tbl, struct net_device *dev,
 {
 	write_lock_bh(&tbl->lock);
 	neigh_flush_dev(tbl, dev, skip_perm);
-	pneigh_ifdown_and_unlock(tbl, dev);
+	if (skip_perm)
+		write_unlock_bh(&tbl->lock);
+	else
+		pneigh_ifdown_and_unlock(tbl, dev);
 	pneigh_queue_purge(&tbl->proxy_queue, dev ? dev_net(dev) : NULL,
 			   tbl->family);
 	if (skb_queue_empty_lockless(&tbl->proxy_queue))
-- 
2.39.0.rc1.256.g54fd8350bd-goog