netdev - [PATCH net-next 02/13] net: dev: Add NETDEV_PRE

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Message-ID: <cc3b70f95924c0b37f845496ea77924f6faf8e68.1544700813.git.petrm@mellanox.com>
Date:   Thu, 13 Dec 2018 11:54:33 +0000
From:   Petr Machata <petrm@...lanox.com>
To:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>
CC:     "j.vosburgh@...il.com" <j.vosburgh@...il.com>,
        "vfalico@...il.com" <vfalico@...il.com>,
        "andy@...yhouse.net" <andy@...yhouse.net>,
        "davem@...emloft.net" <davem@...emloft.net>,
        Jiri Pirko <jiri@...lanox.com>,
        Ido Schimmel <idosch@...lanox.com>,
        "roopa@...ulusnetworks.com" <roopa@...ulusnetworks.com>,
        "nikolay@...ulusnetworks.com" <nikolay@...ulusnetworks.com>
Subject: [PATCH net-next 02/13] 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@...lanox.com>
Acked-by: Jiri Pirko <jiri@...lanox.com>
Reviewed-by: Ido Schimmel <idosch@...lanox.com>
---
 include/linux/netdevice.h | 8 +++++++-
 net/core/dev.c            | 1 +
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index d89875ec21ac..1d5ad053ccf7 100644
--- 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 7250a3a73fa4..01497b7d1bdf 100644
--- 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";
-- 
2.4.11