net: dev: Add NETDEV_PRE_CHANGEADDR

The NETDEV_CHANGEADDR notification is emitted after a device address
changes. Extending this message to allow vetoing is certainly possible,
but several other notification types have instead adopted a simple
two-stage approach: first a "pre" notification is sent to make sure all
interested parties are OK with a change that's about to be done. Then
the change is done, and afterwards a "post" notification is sent.

This dual approach is easier to use: when the change is vetoed, nothing
has changed yet, and it's therefore unnecessary to roll anything back.
Therefore adopt it for NETDEV_CHANGEADDR as well.

To that end, add NETDEV_PRE_CHANGEADDR and an info structure to go along
with it.

Signed-off-by: Petr Machata <petrm@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index d89875ec21ac7a810b47896f5951dcb14d865391..1d5ad053ccf7526fef3f26bf74435514adf6dc62 100644 (file)
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -2450,7 +2450,8 @@ enum netdev_cmd {
        NETDEV_REGISTER,
        NETDEV_UNREGISTER,
        NETDEV_CHANGEMTU,       /* notify after mtu change happened */
-       NETDEV_CHANGEADDR,
+       NETDEV_CHANGEADDR,      /* notify after the address change */
+       NETDEV_PRE_CHANGEADDR,  /* notify before the address change */
        NETDEV_GOING_DOWN,
        NETDEV_CHANGENAME,
        NETDEV_FEAT_CHANGE,
@@ -2512,6 +2513,11 @@ struct netdev_notifier_changelowerstate_info {
        void *lower_state_info; /* is lower dev state */
 };
 
+struct netdev_notifier_pre_changeaddr_info {
+       struct netdev_notifier_info info; /* must be first */
+       const unsigned char *dev_addr;
+};
+
 static inline void netdev_notifier_info_init(struct netdev_notifier_info *info,
                                             struct net_device *dev)
 {

diff --git a/net/core/dev.c b/net/core/dev.c
index 7250a3a73fa4a9300941f8785a85431e1cceaf6d..01497b7d1bdfd0be42acaa1735af9c59bf8f6d33 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1589,6 +1589,7 @@ const char *netdev_cmd_to_name(enum netdev_cmd cmd)
        N(UDP_TUNNEL_DROP_INFO) N(CHANGE_TX_QUEUE_LEN)
        N(CVLAN_FILTER_PUSH_INFO) N(CVLAN_FILTER_DROP_INFO)
        N(SVLAN_FILTER_PUSH_INFO) N(SVLAN_FILTER_DROP_INFO)
+       N(PRE_CHANGEADDR)
        }
 #undef N
        return "UNKNOWN_NETDEV_EVENT";