dev: support deferring device flag change notifications

Split dev_change_flags() into two functions: __dev_change_flags() to
perform the actual changes and __dev_notify_flags() to invoke netdevice
notifiers. This will be used by rtnl_link to defer netlink notifications
until the device has been fully configured.

This changes ordering of some operations, in particular:

- netlink notifications are sent after all changes have been performed.
  As a side effect this surpresses one unnecessary netlink message when
  the IFF_UP and other flags are changed simultaneously.

- The NETDEV_UP/NETDEV_DOWN and NETDEV_CHANGE notifiers are invoked
  after all changes have been performed. Their relative is unchanged.

- net_dmaengine_put() is invoked before the NETDEV_DOWN notifier instead
  of afterwards. This should not make any difference since both RX and TX
  are already shut down at this point.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 1bfda90c2625..c79a88be7c33 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1587,7 +1587,9 @@ extern int		dev_valid_name(const char *name);
 extern int              dev_ioctl(struct net *net, unsigned int cmd, void __user *);
 extern int              dev_ethtool(struct net *net, struct ifreq *);
 extern unsigned         dev_get_flags(const struct net_device *);
+extern int              __dev_change_flags(struct net_device *, unsigned int flags);
 extern int              dev_change_flags(struct net_device *, unsigned);
+extern void             __dev_notify_flags(struct net_device *, unsigned int old_flags);
 extern int              dev_change_name(struct net_device *, const char *);
 extern int              dev_set_alias(struct net_device *, const char *, size_t);
 extern int              dev_change_net_namespace(struct net_device *,