[PATCH net-next] hsr: remove hsr interface if all slaves are removed

[Taehee Yoo]

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 <ap420...@gmail.com>
---
 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 26d6c39f24e1..e2564de67603 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
-- 
2.17.1