hv_netvsc: drop common code until callback model fixed

The callback model of handling network failover is not suitable
in the current form.
  1. It was merged without addressing all the review feedback.
  2. It was merged without approval of any of the netvsc maintainers.
  3. Design discussion on how to handle PV/VF fallback is still
     not complete.
  4. IMHO the code model using callbacks is trying to make
     something common which isn't.

Revert the netvsc specific changes for now. Does not impact ongoing
development of failover model for virtio.
Revisit this after a simpler library based failover kernel
routines are extracted.

This reverts
commit 9c6ffbac ("hv_netvsc: fix error return code in netvsc_probe()")
and
commit 1ff78076 ("netvsc: refactor notifier/event handling code to use the failover framework")
Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/hyperv/Kconfig

@@ -2,6 +2,5 @@ config HYPERV_NET
 	tristate "Microsoft Hyper-V virtual network driver"
 	depends on HYPERV
 	select UCS2_STRING
-	select FAILOVER
 	help
 	  Select this option to enable the Hyper-V virtual network driver.

drivers/net/hyperv/hyperv_net.h

@@ -931,8 +931,6 @@ struct net_device_context {
 	u32 vf_alloc;
 	/* Serial number of the VF to team with */
 	u32 vf_serial;
-
-	struct failover *failover;
 };
 
 /* Per channel data */

drivers/net/hyperv/netvsc_drv.c

@@ -42,7 +42,6 @@
 #include <net/pkt_sched.h>
 #include <net/checksum.h>
 #include <net/ip6_checksum.h>
-#include <net/failover.h>
 
 #include "hyperv_net.h"
 
@@ -1780,6 +1779,46 @@ static void netvsc_link_change(struct work_struct *w)
 	rtnl_unlock();
 }
 
+static struct net_device *get_netvsc_bymac(const u8 *mac)
+{
+	struct net_device *dev;
+
+	ASSERT_RTNL();
+
+	for_each_netdev(&init_net, dev) {
+		if (dev->netdev_ops != &device_ops)
+			continue;	/* not a netvsc device */
+
+		if (ether_addr_equal(mac, dev->perm_addr))
+			return dev;
+	}
+
+	return NULL;
+}
+
+static struct net_device *get_netvsc_byref(struct net_device *vf_netdev)
+{
+	struct net_device *dev;
+
+	ASSERT_RTNL();
+
+	for_each_netdev(&init_net, dev) {
+		struct net_device_context *net_device_ctx;
+
+		if (dev->netdev_ops != &device_ops)
+			continue;	/* not a netvsc device */
+
+		net_device_ctx = netdev_priv(dev);
+		if (!rtnl_dereference(net_device_ctx->nvdev))
+			continue;	/* device is removed */
+
+		if (rtnl_dereference(net_device_ctx->vf_netdev) == vf_netdev)
+			return dev;	/* a match */
+	}
+
+	return NULL;
+}
+
 /* Called when VF is injecting data into network stack.
  * Change the associated network device from VF to netvsc.
  * note: already called with rcu_read_lock
@@ -1802,6 +1841,46 @@ static rx_handler_result_t netvsc_vf_handle_frame(struct sk_buff **pskb)
 	return RX_HANDLER_ANOTHER;
 }
 
+static int netvsc_vf_join(struct net_device *vf_netdev,
+			  struct net_device *ndev)
+{
+	struct net_device_context *ndev_ctx = netdev_priv(ndev);
+	int ret;
+
+	ret = netdev_rx_handler_register(vf_netdev,
+					 netvsc_vf_handle_frame, ndev);
+	if (ret != 0) {
+		netdev_err(vf_netdev,
+			   "can not register netvsc VF receive handler (err = %d)\n",
+			   ret);
+		goto rx_handler_failed;
+	}
+
+	ret = netdev_master_upper_dev_link(vf_netdev, ndev,
+					   NULL, NULL, NULL);
+	if (ret != 0) {
+		netdev_err(vf_netdev,
+			   "can not set master device %s (err = %d)\n",
+			   ndev->name, ret);
+		goto upper_link_failed;
+	}
+
+	/* set slave flag before open to prevent IPv6 addrconf */
+	vf_netdev->flags |= IFF_SLAVE;
+
+	schedule_delayed_work(&ndev_ctx->vf_takeover, VF_TAKEOVER_INT);
+
+	call_netdevice_notifiers(NETDEV_JOIN, vf_netdev);
+
+	netdev_info(vf_netdev, "joined to %s\n", ndev->name);
+	return 0;
+
+upper_link_failed:
+	netdev_rx_handler_unregister(vf_netdev);
+rx_handler_failed:
+	return ret;
+}
+
 static void __netvsc_vf_setup(struct net_device *ndev,
 			      struct net_device *vf_netdev)
 {
@@ -1852,95 +1931,85 @@ static void netvsc_vf_setup(struct work_struct *w)
 	rtnl_unlock();
 }
 
-static int netvsc_pre_register_vf(struct net_device *vf_netdev,
-				  struct net_device *ndev)
+static int netvsc_register_vf(struct net_device *vf_netdev)
 {
+	struct net_device *ndev;
 	struct net_device_context *net_device_ctx;
 	struct netvsc_device *netvsc_dev;
 
+	if (vf_netdev->addr_len != ETH_ALEN)
+		return NOTIFY_DONE;
+
+	/*
+	 * We will use the MAC address to locate the synthetic interface to
+	 * associate with the VF interface. If we don't find a matching
+	 * synthetic interface, move on.
+	 */
+	ndev = get_netvsc_bymac(vf_netdev->perm_addr);
+	if (!ndev)
+		return NOTIFY_DONE;
+
 	net_device_ctx = netdev_priv(ndev);
 	netvsc_dev = rtnl_dereference(net_device_ctx->nvdev);
 	if (!netvsc_dev || rtnl_dereference(net_device_ctx->vf_netdev))
-		return -ENODEV;
-
-	return 0;
-}
+		return NOTIFY_DONE;
 
-static int netvsc_register_vf(struct net_device *vf_netdev,
-			      struct net_device *ndev)
-{
-	struct net_device_context *ndev_ctx = netdev_priv(ndev);
+	if (netvsc_vf_join(vf_netdev, ndev) != 0)
+		return NOTIFY_DONE;
 
-	/* set slave flag before open to prevent IPv6 addrconf */
-	vf_netdev->flags |= IFF_SLAVE;
-
-	schedule_delayed_work(&ndev_ctx->vf_takeover, VF_TAKEOVER_INT);
-
-	call_netdevice_notifiers(NETDEV_JOIN, vf_netdev);
-
-	netdev_info(vf_netdev, "joined to %s\n", ndev->name);
+	netdev_info(ndev, "VF registering: %s\n", vf_netdev->name);
 
 	dev_hold(vf_netdev);
-	rcu_assign_pointer(ndev_ctx->vf_netdev, vf_netdev);
-
-	return 0;
+	rcu_assign_pointer(net_device_ctx->vf_netdev, vf_netdev);
+	return NOTIFY_OK;
 }
 
 /* VF up/down change detected, schedule to change data path */
-static int netvsc_vf_changed(struct net_device *vf_netdev,
-			     struct net_device *ndev)
+static int netvsc_vf_changed(struct net_device *vf_netdev)
 {
 	struct net_device_context *net_device_ctx;
 	struct netvsc_device *netvsc_dev;
+	struct net_device *ndev;
 	bool vf_is_up = netif_running(vf_netdev);
 
+	ndev = get_netvsc_byref(vf_netdev);
+	if (!ndev)
+		return NOTIFY_DONE;
+
 	net_device_ctx = netdev_priv(ndev);
 	netvsc_dev = rtnl_dereference(net_device_ctx->nvdev);
 	if (!netvsc_dev)
-		return -ENODEV;
+		return NOTIFY_DONE;
 
 	netvsc_switch_datapath(ndev, vf_is_up);
 	netdev_info(ndev, "Data path switched %s VF: %s\n",
 		    vf_is_up ? "to" : "from", vf_netdev->name);
 
-	return 0;
+	return NOTIFY_OK;
 }
 
-static int netvsc_pre_unregister_vf(struct net_device *vf_netdev,
-				    struct net_device *ndev)
+static int netvsc_unregister_vf(struct net_device *vf_netdev)
 {
+	struct net_device *ndev;
 	struct net_device_context *net_device_ctx;
 
-	net_device_ctx = netdev_priv(ndev);
-	cancel_delayed_work_sync(&net_device_ctx->vf_takeover);
-
-	return 0;
-}
-
-static int netvsc_unregister_vf(struct net_device *vf_netdev,
-				struct net_device *ndev)
-{
-	struct net_device_context *net_device_ctx;
+	ndev = get_netvsc_byref(vf_netdev);
+	if (!ndev)
+		return NOTIFY_DONE;
 
 	net_device_ctx = netdev_priv(ndev);
+	cancel_delayed_work_sync(&net_device_ctx->vf_takeover);
 
 	netdev_info(ndev, "VF unregistering: %s\n", vf_netdev->name);
 
+	netdev_rx_handler_unregister(vf_netdev);
+	netdev_upper_dev_unlink(vf_netdev, ndev);
 	RCU_INIT_POINTER(net_device_ctx->vf_netdev, NULL);
 	dev_put(vf_netdev);
 
-	return 0;
+	return NOTIFY_OK;
 }
 
-static struct failover_ops netvsc_failover_ops = {
-	.slave_pre_register	= netvsc_pre_register_vf,
-	.slave_register		= netvsc_register_vf,
-	.slave_pre_unregister	= netvsc_pre_unregister_vf,
-	.slave_unregister	= netvsc_unregister_vf,
-	.slave_link_change	= netvsc_vf_changed,
-	.slave_handle_frame	= netvsc_vf_handle_frame,
-};
-
 static int netvsc_probe(struct hv_device *dev,
 			const struct hv_vmbus_device_id *dev_id)
 {
@@ -2030,16 +2099,8 @@ static int netvsc_probe(struct hv_device *dev,
 		goto register_failed;
 	}
 
-	net_device_ctx->failover = failover_register(net, &netvsc_failover_ops);
-	if (IS_ERR(net_device_ctx->failover)) {
-		ret = PTR_ERR(net_device_ctx->failover);
-		goto err_failover;
-	}
-
 	return ret;
 
-err_failover:
-	unregister_netdev(net);
 register_failed:
 	rndis_filter_device_remove(dev, nvdev);
 rndis_failed:
@@ -2080,15 +2141,13 @@ static int netvsc_remove(struct hv_device *dev)
 	rtnl_lock();
 	vf_netdev = rtnl_dereference(ndev_ctx->vf_netdev);
 	if (vf_netdev)
-		failover_slave_unregister(vf_netdev);
+		netvsc_unregister_vf(vf_netdev);
 
 	if (nvdev)
 		rndis_filter_device_remove(dev, nvdev);
 
 	unregister_netdevice(net);
 
-	failover_unregister(ndev_ctx->failover);
-
 	rtnl_unlock();
 	rcu_read_unlock();
 
@@ -2115,8 +2174,54 @@ static struct  hv_driver netvsc_drv = {
 	.remove = netvsc_remove,
 };
 
+/*
+ * On Hyper-V, every VF interface is matched with a corresponding
+ * synthetic interface. The synthetic interface is presented first
+ * to the guest. When the corresponding VF instance is registered,
+ * we will take care of switching the data path.
+ */
+static int netvsc_netdev_event(struct notifier_block *this,
+			       unsigned long event, void *ptr)
+{
+	struct net_device *event_dev = netdev_notifier_info_to_dev(ptr);
+
+	/* Skip our own events */
+	if (event_dev->netdev_ops == &device_ops)
+		return NOTIFY_DONE;
+
+	/* Avoid non-Ethernet type devices */
+	if (event_dev->type != ARPHRD_ETHER)
+		return NOTIFY_DONE;
+
+	/* Avoid Vlan dev with same MAC registering as VF */
+	if (is_vlan_dev(event_dev))
+		return NOTIFY_DONE;
+
+	/* Avoid Bonding master dev with same MAC registering as VF */
+	if ((event_dev->priv_flags & IFF_BONDING) &&
+	    (event_dev->flags & IFF_MASTER))
+		return NOTIFY_DONE;
+
+	switch (event) {
+	case NETDEV_REGISTER:
+		return netvsc_register_vf(event_dev);
+	case NETDEV_UNREGISTER:
+		return netvsc_unregister_vf(event_dev);
+	case NETDEV_UP:
+	case NETDEV_DOWN:
+		return netvsc_vf_changed(event_dev);
+	default:
+		return NOTIFY_DONE;
+	}
+}
+
+static struct notifier_block netvsc_netdev_notifier = {
+	.notifier_call = netvsc_netdev_event,
+};
+
 static void __exit netvsc_drv_exit(void)
 {
+	unregister_netdevice_notifier(&netvsc_netdev_notifier);
 	vmbus_driver_unregister(&netvsc_drv);
 }
 
@@ -2135,6 +2240,7 @@ static int __init netvsc_drv_init(void)
 	if (ret)
 		return ret;
 
+	register_netdevice_notifier(&netvsc_netdev_notifier);
 	return 0;
 }