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>

15 files changed, 51 insertions, 32 deletions

diff --git a/net/8021q/vlan.c b/net/8021q/vlan.c
index aef1a977279c..dc4411165e43 100644
--- a/net/8021q/vlan.c
+++ b/net/8021q/vlan.c
@@ -358,6 +358,7 @@ static int __vlan_device_event(struct net_device *dev, unsigned long event)
 static int vlan_device_event(struct notifier_block *unused, unsigned long event,
 			     void *ptr)
 {
+	struct netlink_ext_ack *extack = netdev_notifier_info_to_extack(ptr);
 	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 	struct vlan_group *grp;
 	struct vlan_info *vlan_info;
@@ -460,7 +461,8 @@ static int vlan_device_event(struct notifier_block *unused, unsigned long event,
 
 			vlan = vlan_dev_priv(vlandev);
 			if (!(vlan->flags & VLAN_FLAG_LOOSE_BINDING))
-				dev_change_flags(vlandev, flgs | IFF_UP);
+				dev_change_flags(vlandev, flgs | IFF_UP,
+						 extack);
 			netif_stacked_transfer_operstate(dev, vlandev);
 		}
 		break;
diff --git a/net/bluetooth/6lowpan.c b/net/bluetooth/6lowpan.c
index 828e87fe8027..9d79c7de234a 100644
--- a/net/bluetooth/6lowpan.c
+++ b/net/bluetooth/6lowpan.c
@@ -607,7 +607,7 @@ static void ifup(struct net_device *netdev)
 	int err;
 
 	rtnl_lock();
-	err = dev_open(netdev);
+	err = dev_open(netdev, NULL);
 	if (err < 0)
 		BT_INFO("iface %s cannot be opened (%d)", netdev->name, err);
 	rtnl_unlock();
diff --git a/net/core/dev.c b/net/core/dev.c
index 04a6b7100aac..068b60db35ae 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;
 
diff --git a/net/core/dev_ioctl.c b/net/core/dev_ioctl.c
index 90e8aa36881e..da273ec3cc57 100644
--- a/net/core/dev_ioctl.c
+++ b/net/core/dev_ioctl.c
@@ -234,7 +234,7 @@ static int dev_ifsioc(struct net *net, struct ifreq *ifr, unsigned int cmd)
 
 	switch (cmd) {
 	case SIOCSIFFLAGS:	/* Set interface flags */
-		return dev_change_flags(dev, ifr->ifr_flags);
+		return dev_change_flags(dev, ifr->ifr_flags, NULL);
 
 	case SIOCSIFMETRIC:	/* Set the metric on the interface
 				   (currently unused) */
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index bd67c4d0fcfd..ff9fd2bb4ce4 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -337,7 +337,7 @@ NETDEVICE_SHOW_RW(mtu, fmt_dec);
 
 static int change_flags(struct net_device *dev, unsigned long new_flags)
 {
-	return dev_change_flags(dev, (unsigned int)new_flags);
+	return dev_change_flags(dev, (unsigned int)new_flags, NULL);
 }
 
 static ssize_t flags_store(struct device *dev, struct device_attribute *attr,
diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 2b9fdbc43205..36a2b63ffd6d 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -663,7 +663,7 @@ int netpoll_setup(struct netpoll *np)
 
 		np_info(np, "device %s not up yet, forcing it\n", np->dev_name);
 
-		err = dev_open(ndev);
+		err = dev_open(ndev, NULL);
 
 		if (err) {
 			np_err(np, "failed to open %s\n", ndev->name);
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 98876cd1e36c..91a0f7477f8e 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -2489,7 +2489,8 @@ static int do_setlink(const struct sk_buff *skb,
 	}
 
 	if (ifm->ifi_flags || ifm->ifi_change) {
-		err = dev_change_flags(dev, rtnl_dev_combine_flags(dev, ifm));
+		err = dev_change_flags(dev, rtnl_dev_combine_flags(dev, ifm),
+				       extack);
 		if (err < 0)
 			goto errout;
 	}
@@ -2870,7 +2871,8 @@ int rtnl_configure_link(struct net_device *dev, const struct ifinfomsg *ifm)
 
 	old_flags = dev->flags;
 	if (ifm && (ifm->ifi_flags || ifm->ifi_change)) {
-		err = __dev_change_flags(dev, rtnl_dev_combine_flags(dev, ifm));
+		err = __dev_change_flags(dev, rtnl_dev_combine_flags(dev, ifm),
+					 NULL);
 		if (err < 0)
 			return err;
 	}
diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index a34602ae27de..5b9b6d497f71 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -1100,7 +1100,7 @@ int devinet_ioctl(struct net *net, unsigned int cmd, struct ifreq *ifr)
 				inet_del_ifa(in_dev, ifap, 1);
 			break;
 		}
-		ret = dev_change_flags(dev, ifr->ifr_flags);
+		ret = dev_change_flags(dev, ifr->ifr_flags, NULL);
 		break;
 
 	case SIOCSIFADDR:	/* Set interface address (and family) */
diff --git a/net/ipv4/ipconfig.c b/net/ipv4/ipconfig.c
index 88212615bf4c..55757764c381 100644
--- a/net/ipv4/ipconfig.c
+++ b/net/ipv4/ipconfig.c
@@ -220,7 +220,7 @@ static int __init ic_open_devs(void)
 	for_each_netdev(&init_net, dev) {
 		if (!(dev->flags & IFF_LOOPBACK) && !netdev_uses_dsa(dev))
 			continue;
-		if (dev_change_flags(dev, dev->flags | IFF_UP) < 0)
+		if (dev_change_flags(dev, dev->flags | IFF_UP, NULL) < 0)
 			pr_err("IP-Config: Failed to open %s\n", dev->name);
 	}
 
@@ -238,7 +238,7 @@ static int __init ic_open_devs(void)
 			if (ic_proto_enabled && !able)
 				continue;
 			oflags = dev->flags;
-			if (dev_change_flags(dev, oflags | IFF_UP) < 0) {
+			if (dev_change_flags(dev, oflags | IFF_UP, NULL) < 0) {
 				pr_err("IP-Config: Failed to open %s\n",
 				       dev->name);
 				continue;
@@ -315,7 +315,7 @@ static void __init ic_close_devs(void)
 		dev = d->dev;
 		if (d != ic_dev && !netdev_uses_dsa(dev)) {
 			pr_debug("IP-Config: Downing %s\n", dev->name);
-			dev_change_flags(dev, d->flags);
+			dev_change_flags(dev, d->flags, NULL);
 		}
 		kfree(d);
 	}
diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index 5cbc749a50aa..ea04e38f56e9 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -506,7 +506,7 @@ static struct net_device *ipmr_new_tunnel(struct net *net, struct vifctl *v)
 			dev->flags |= IFF_MULTICAST;
 			if (!ipmr_init_vif_indev(dev))
 				goto failure;
-			if (dev_open(dev))
+			if (dev_open(dev, NULL))
 				goto failure;
 			dev_hold(dev);
 		}
@@ -589,7 +589,7 @@ static struct net_device *ipmr_reg_vif(struct net *net, struct mr_table *mrt)
 
 	if (!ipmr_init_vif_indev(dev))
 		goto failure;
-	if (dev_open(dev))
+	if (dev_open(dev, NULL))
 		goto failure;
 
 	dev_hold(dev);
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 045597b9a7c0..521e471f1cf9 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -2820,7 +2820,7 @@ int addrconf_set_dstaddr(struct net *net, void __user *arg)
 			dev = __dev_get_by_name(net, p.name);
 			if (!dev)
 				goto err_exit;
-			err = dev_open(dev);
+			err = dev_open(dev, NULL);
 		}
 	}
 #endif
diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index e2ea691e42c6..8c63494400c4 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -655,7 +655,7 @@ static struct net_device *ip6mr_reg_vif(struct net *net, struct mr_table *mrt)
 		return NULL;
 	}
 
-	if (dev_open(dev))
+	if (dev_open(dev, NULL))
 		goto failure;
 
 	dev_hold(dev);
diff --git a/net/openvswitch/vport-geneve.c b/net/openvswitch/vport-geneve.c
index 5aaf3babfc3f..acb6077b7478 100644
--- a/net/openvswitch/vport-geneve.c
+++ b/net/openvswitch/vport-geneve.c
@@ -93,7 +93,7 @@ static struct vport *geneve_tnl_create(const struct vport_parms *parms)
 		return ERR_CAST(dev);
 	}
 
-	err = dev_change_flags(dev, dev->flags | IFF_UP);
+	err = dev_change_flags(dev, dev->flags | IFF_UP, NULL);
 	if (err < 0) {
 		rtnl_delete_link(dev);
 		rtnl_unlock();
diff --git a/net/openvswitch/vport-gre.c b/net/openvswitch/vport-gre.c
index 0e72d95b0e8f..c38a62464b85 100644
--- a/net/openvswitch/vport-gre.c
+++ b/net/openvswitch/vport-gre.c
@@ -68,7 +68,7 @@ static struct vport *gre_tnl_create(const struct vport_parms *parms)
 		return ERR_CAST(dev);
 	}
 
-	err = dev_change_flags(dev, dev->flags | IFF_UP);
+	err = dev_change_flags(dev, dev->flags | IFF_UP, NULL);
 	if (err < 0) {
 		rtnl_delete_link(dev);
 		rtnl_unlock();
diff --git a/net/openvswitch/vport-vxlan.c b/net/openvswitch/vport-vxlan.c
index 7e6301b2ec4d..8f16f11f7ad3 100644
--- a/net/openvswitch/vport-vxlan.c
+++ b/net/openvswitch/vport-vxlan.c
@@ -131,7 +131,7 @@ static struct vport *vxlan_tnl_create(const struct vport_parms *parms)
 		return ERR_CAST(dev);
 	}
 
-	err = dev_change_flags(dev, dev->flags | IFF_UP);
+	err = dev_change_flags(dev, dev->flags | IFF_UP, NULL);
 	if (err < 0) {
 		rtnl_delete_link(dev);
 		rtnl_unlock();