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, 29 insertions, 14 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index 04a6b7100aac8..068b60db35aed 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -162,6 +162,9 @@ static struct list_head offload_base __read_mostly;
 static int netif_rx_internal(struct sk_buff *skb);
 static int call_netdevice_notifiers_info(unsigned long val,
 					 struct netdev_notifier_info *info);
+static int call_netdevice_notifiers_extack(unsigned long val,
+					   struct net_device *dev,
+					   struct netlink_ext_ack *extack);
 static struct napi_struct *napi_by_id(unsigned int napi_id);
 
 /*
@@ -1361,7 +1364,7 @@ void netdev_notify_peers(struct net_device *dev)
 }
 EXPORT_SYMBOL(netdev_notify_peers);
 
-static int __dev_open(struct net_device *dev)
+static int __dev_open(struct net_device *dev, struct netlink_ext_ack *extack)
 {
 	const struct net_device_ops *ops = dev->netdev_ops;
 	int ret;
@@ -1377,7 +1380,7 @@ static int __dev_open(struct net_device *dev)
 	 */
 	netpoll_poll_disable(dev);
 
-	ret = call_netdevice_notifiers(NETDEV_PRE_UP, dev);
+	ret = call_netdevice_notifiers_extack(NETDEV_PRE_UP, dev, extack);
 	ret = notifier_to_errno(ret);
 	if (ret)
 		return ret;
@@ -1406,7 +1409,8 @@ static int __dev_open(struct net_device *dev)
 
 /**
  *	dev_open	- prepare an interface for use.
- *	@dev:	device to open
+ *	@dev: device to open
+ *	@extack: netlink extended ack
  *
  *	Takes a device from down to up state. The device's private open
  *	function is invoked and then the multicast lists are loaded. Finally
@@ -1416,14 +1420,14 @@ static int __dev_open(struct net_device *dev)
  *	Calling this function on an active interface is a nop. On a failure
  *	a negative errno code is returned.
  */
-int dev_open(struct net_device *dev)
+int dev_open(struct net_device *dev, struct netlink_ext_ack *extack)
 {
 	int ret;
 
 	if (dev->flags & IFF_UP)
 		return 0;
 
-	ret = __dev_open(dev);
+	ret = __dev_open(dev, extack);
 	if (ret < 0)
 		return ret;
 
@@ -1733,6 +1737,18 @@ static int call_netdevice_notifiers_info(unsigned long val,
 	return raw_notifier_call_chain(&netdev_chain, val, info);
 }
 
+static int call_netdevice_notifiers_extack(unsigned long val,
+					   struct net_device *dev,
+					   struct netlink_ext_ack *extack)
+{
+	struct netdev_notifier_info info = {
+		.dev = dev,
+		.extack = extack,
+	};
+
+	return call_netdevice_notifiers_info(val, &info);
+}
+
 /**
  *	call_netdevice_notifiers - call all network notifier blocks
  *      @val: value passed unmodified to notifier function
@@ -1744,11 +1760,7 @@ static int call_netdevice_notifiers_info(unsigned long val,
 
 int call_netdevice_notifiers(unsigned long val, struct net_device *dev)
 {
-	struct netdev_notifier_info info = {
-		.dev = dev,
-	};
-
-	return call_netdevice_notifiers_info(val, &info);
+	return call_netdevice_notifiers_extack(val, dev, NULL);
 }
 EXPORT_SYMBOL(call_netdevice_notifiers);
 
@@ -7497,7 +7509,8 @@ unsigned int dev_get_flags(const struct net_device *dev)
 }
 EXPORT_SYMBOL(dev_get_flags);
 
-int __dev_change_flags(struct net_device *dev, unsigned int flags)
+int __dev_change_flags(struct net_device *dev, unsigned int flags,
+		       struct netlink_ext_ack *extack)
 {
 	unsigned int old_flags = dev->flags;
 	int ret;
@@ -7534,7 +7547,7 @@ int __dev_change_flags(struct net_device *dev, unsigned int flags)
 		if (old_flags & IFF_UP)
 			__dev_close(dev);
 		else
-			ret = __dev_open(dev);
+			ret = __dev_open(dev, extack);
 	}
 
 	if ((flags ^ dev->gflags) & IFF_PROMISC) {
@@ -7594,16 +7607,18 @@ void __dev_notify_flags(struct net_device *dev, unsigned int old_flags,
  *	dev_change_flags - change device settings
  *	@dev: device
  *	@flags: device state flags
+ *	@extack: netlink extended ack
  *
  *	Change settings on device based state flags. The flags are
  *	in the userspace exported format.
  */
-int dev_change_flags(struct net_device *dev, unsigned int flags)
+int dev_change_flags(struct net_device *dev, unsigned int flags,
+		     struct netlink_ext_ack *extack)
 {
 	int ret;
 	unsigned int changes, old_flags = dev->flags, old_gflags = dev->gflags;
 
-	ret = __dev_change_flags(dev, flags);
+	ret = __dev_change_flags(dev, flags, extack);
 	if (ret < 0)
 		return ret;