From 573c7ba006edbecff0714db651dd3602b9d0a6a0 Mon Sep 17 00:00:00 2001
From: Jiri Pirko <jiri@mellanox.com>
Date: Fri, 16 Oct 2015 14:01:22 +0200
Subject: [PATCH] net: introduce pre-change upper device notifier
This newly introduced netdevice notifier is called before actual change
upper happens. That provides a possibility for notifier handlers to
know upper change will happen and react to it, including possibility to
forbid the change. That is valuable for drivers which can check if the
upper device linkage is supported and forbid that in case it is not.
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
include/linux/netdevice.h | 1 +
net/core/dev.c | 9 +++++++++
2 files changed, 10 insertions(+)
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index b3374402c1ea1..69fdd427c8cb8 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -2106,6 +2106,7 @@ struct pcpu_sw_netstats {
#define NETDEV_PRECHANGEMTU 0x0017 /* notify before mtu change happened */
#define NETDEV_CHANGEINFODATA 0x0018
#define NETDEV_BONDING_INFO 0x0019
+#define NETDEV_PRECHANGEUPPER 0x001A
int register_netdevice_notifier(struct notifier_block *nb);
int unregister_netdevice_notifier(struct notifier_block *nb);
diff --git a/net/core/dev.c b/net/core/dev.c
index a229bf0d649dc..1225b4be8ed6e 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5346,6 +5346,12 @@ static int __netdev_upper_dev_link(struct net_device *dev,
changeupper_info.master = master;
changeupper_info.linking = true;
+ ret = call_netdevice_notifiers_info(NETDEV_PRECHANGEUPPER, dev,
+ &changeupper_info.info);
+ ret = notifier_to_errno(ret);
+ if (ret)
+ return ret;
+
ret = __netdev_adjacent_dev_link_neighbour(dev, upper_dev, private,
master);
if (ret)
@@ -5488,6 +5494,9 @@ void netdev_upper_dev_unlink(struct net_device *dev,
changeupper_info.master = netdev_master_upper_dev_get(dev) == upper_dev;
changeupper_info.linking = false;
+ call_netdevice_notifiers_info(NETDEV_PRECHANGEUPPER, dev,
+ &changeupper_info.info);
+
__netdev_adjacent_dev_unlink_neighbour(dev, upper_dev);
/* Here is the tricky part. We must remove all dev's lower
--
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