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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Haishuang Yan <yanhaishuang@cmss.chinamobile.com>,
        Florian Westphal <fw@strlen.de>,
        "David S. Miller" <davem@davemloft.net>,
        syzbot+68a8ed58e3d17c700de5@syzkaller.appspotmail.com
Subject: [PATCH 4.19 007/116] geneve: move debug check after netdev unregister
Date:   Wed,  1 Apr 2020 18:16:23 +0200
Message-Id: <20200401161543.245711159@linuxfoundation.org>
In-Reply-To: <20200401161542.669484650@linuxfoundation.org>
References: <20200401161542.669484650@linuxfoundation.org>
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From: Florian Westphal <fw@strlen.de>

[ Upstream commit 0fda7600c2e174fe27e9cf02e78e345226e441fa ]

The debug check must be done after unregister_netdevice_many() call --
the list_del() for this is done inside .ndo_stop.

Fixes: 2843a25348f8 ("geneve: speedup geneve tunnels dismantle")
Reported-and-tested-by: <syzbot+68a8ed58e3d17c700de5@syzkaller.appspotmail.com>
Cc: Haishuang Yan <yanhaishuang@cmss.chinamobile.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/geneve.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- a/drivers/net/geneve.c
+++ b/drivers/net/geneve.c
@@ -1725,8 +1725,6 @@ static void geneve_destroy_tunnels(struc
 		if (!net_eq(dev_net(geneve->dev), net))
 			unregister_netdevice_queue(geneve->dev, head);
 	}
-
-	WARN_ON_ONCE(!list_empty(&gn->sock_list));
 }
 
 static void __net_exit geneve_exit_batch_net(struct list_head *net_list)
@@ -1741,6 +1739,12 @@ static void __net_exit geneve_exit_batch
 	/* unregister the devices gathered above */
 	unregister_netdevice_many(&list);
 	rtnl_unlock();
+
+	list_for_each_entry(net, net_list, exit_list) {
+		const struct geneve_net *gn = net_generic(net, geneve_net_id);
+
+		WARN_ON_ONCE(!list_empty(&gn->sock_list));
+	}
 }
 
 static struct pernet_operations geneve_net_ops = {