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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, Taehee Yoo <ap420073@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.7 056/112] hsr: remove hsr interface if all slaves are removed
Date:   Tue,  7 Jul 2020 17:17:01 +0200
Message-Id: <20200707145803.665343106@linuxfoundation.org>
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From: Taehee Yoo <ap420073@gmail.com>

[ Upstream commit 34a9c361dd480041d790fff3d6ea58513c8769e8 ]

When all hsr slave interfaces are removed, hsr interface doesn't work.
At that moment, it's fine to remove an unused hsr interface automatically
for saving resources.
That's a common behavior of virtual interfaces.

Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/hsr/hsr_main.c | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/net/hsr/hsr_main.c b/net/hsr/hsr_main.c
index 26d6c39f24e16..e2564de676038 100644
--- a/net/hsr/hsr_main.c
+++ b/net/hsr/hsr_main.c
@@ -15,12 +15,23 @@
 #include "hsr_framereg.h"
 #include "hsr_slave.h"
 
+static bool hsr_slave_empty(struct hsr_priv *hsr)
+{
+	struct hsr_port *port;
+
+	hsr_for_each_port(hsr, port)
+		if (port->type != HSR_PT_MASTER)
+			return false;
+	return true;
+}
+
 static int hsr_netdev_notify(struct notifier_block *nb, unsigned long event,
 			     void *ptr)
 {
-	struct net_device *dev;
 	struct hsr_port *port, *master;
+	struct net_device *dev;
 	struct hsr_priv *hsr;
+	LIST_HEAD(list_kill);
 	int mtu_max;
 	int res;
 
@@ -85,8 +96,15 @@ static int hsr_netdev_notify(struct notifier_block *nb, unsigned long event,
 		master->dev->mtu = mtu_max;
 		break;
 	case NETDEV_UNREGISTER:
-		if (!is_hsr_master(dev))
+		if (!is_hsr_master(dev)) {
+			master = hsr_port_get_hsr(port->hsr, HSR_PT_MASTER);
 			hsr_del_port(port);
+			if (hsr_slave_empty(master->hsr)) {
+				unregister_netdevice_queue(master->dev,
+							   &list_kill);
+				unregister_netdevice_many(&list_kill);
+			}
+		}
 		break;
 	case NETDEV_PRE_TYPE_CHANGE:
 		/* HSR works only on Ethernet devices. Refuse slave to change
-- 
2.25.1