Merge branch 'Pass-extack-to-NETDEV_PRE_UP'

Petr Machata says:

====================
Pass extack to NETDEV_PRE_UP

Drivers may need to validate configuration of a device that's about to
be upped. An example is mlxsw, which needs to check the configuration of
a VXLAN device attached to an offloaded bridge. Should the validation
fail, there's currently no way to communicate details of the failure to
the user, beyond an error number.

Therefore this patch set extends the NETDEV_PRE_UP event to include
extack, if available.

There are three vectors through which NETDEV_PRE_UP invocation can be
reached. The two major ones are dev_open() and dev_change_flags(), the
last is then __dev_change_flags().

In patch #1, the first access vector, dev_open() is addressed. An extack
parameter is added and all users converted to use it.

Before addressing the second vector, two preparatory patches propagate
extack argument to the proximity of the dev_change_flags() call in VRF
and IPVLAN drivers. That happens in patches #2 and #3. Then in patch #4,
dev_change_flags() is treated similarly to dev_open().

Likewise in patch #5, __dev_change_flags() is extended.

Then in patches #6 and #7, the extack is finally propagated all the way
to the point where the notification is emitted.

This change allows particularly mlxsw (which already has code to
leverage extack if available) to communicate to the user error messages
regarding VXLAN configuration. In patch #8, add a test case that
exercises this code and checks that an error message is propagated.

For example:

	local 192.0.2.17 remote 192.0.2.18 \
	dstport 4789 nolearning noudpcsum tos inherit ttl 100
	local 192.0.2.17 remote 192.0.2.18 \
	dstport 4789 nolearning noudpcsum tos inherit ttl 100
Error: mlxsw_spectrum: Conflicting NVE tunnels configuration.

v2:
- Add David Ahern's tags.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 3 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 94fb2e12f117..fc6ba71513be 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -2605,7 +2605,7 @@ struct net_device *dev_get_by_name(struct net *net, const char *name);
 struct net_device *dev_get_by_name_rcu(struct net *net, const char *name);
 struct net_device *__dev_get_by_name(struct net *net, const char *name);
 int dev_alloc_name(struct net_device *dev, const char *name);
-int dev_open(struct net_device *dev);
+int dev_open(struct net_device *dev, struct netlink_ext_ack *extack);
 void dev_close(struct net_device *dev);
 void dev_close_many(struct list_head *head, bool unlink);
 void dev_disable_lro(struct net_device *dev);
@@ -3611,8 +3611,10 @@ int dev_ioctl(struct net *net, unsigned int cmd, struct ifreq *ifr,
 int dev_ifconf(struct net *net, struct ifconf *, int);
 int dev_ethtool(struct net *net, struct ifreq *);
 unsigned int dev_get_flags(const struct net_device *);
-int __dev_change_flags(struct net_device *, unsigned int flags);
-int dev_change_flags(struct net_device *, unsigned int);
+int __dev_change_flags(struct net_device *dev, unsigned int flags,
+		       struct netlink_ext_ack *extack);
+int dev_change_flags(struct net_device *dev, unsigned int flags,
+		     struct netlink_ext_ack *extack);
 void __dev_notify_flags(struct net_device *, unsigned int old_flags,
 			unsigned int gchanges);
 int dev_change_name(struct net_device *, const char *);