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Date:   Tue, 19 Dec 2017 11:35:37 -0800
From:   Stephen Hemminger <stephen@...workplumber.org>
To:     netdev@...r.kernel.org
Cc:     Stephen Hemminger <sthemmin@...rosoft.com>
Subject: [RFC] hv_netvsc: automatically name slave VF network device

Rename the VF device to ethX_vf based on the ethX as the
synthetic device.  This eliminates the need for delay on setup,
and the PCI (udev based) naming is not reproducible on Hyper-V
anyway. The name of the VF does not matter since all control
operations take place the primary device. It does make the
user experience better to associate the names.

Based on feedback from all.systems.go talk.
The downside is that it requires exporting a symbol from netdev
core which makes it harder to backport.

Signed-off-by: Stephen Hemminger <sthemmin@...rosoft.com>
---
 drivers/net/hyperv/hyperv_net.h |  1 -
 drivers/net/hyperv/netvsc_drv.c | 53 +++++++++++------------------------------
 net/core/dev.c                  |  1 +
 3 files changed, 15 insertions(+), 40 deletions(-)

diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
index 0db3bd1ea06f..5013189123e6 100644
--- a/drivers/net/hyperv/hyperv_net.h
+++ b/drivers/net/hyperv/hyperv_net.h
@@ -762,7 +762,6 @@ struct net_device_context {
 	/* State to manage the associated VF interface. */
 	struct net_device __rcu *vf_netdev;
 	struct netvsc_vf_pcpu_stats __percpu *vf_stats;
-	struct delayed_work vf_takeover;
 
 	/* 1: allocated, serial number is valid. 0: not allocated */
 	u32 vf_alloc;
diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index c5584c2d440e..8a0afe9a5064 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -49,7 +49,6 @@
 #define RING_SIZE_MIN		64
 
 #define LINKCHANGE_INT (2 * HZ)
-#define VF_TAKEOVER_INT (HZ / 10)
 
 static unsigned int ring_size __ro_after_init = 128;
 module_param(ring_size, uint, S_IRUGO);
@@ -1760,7 +1759,7 @@ static rx_handler_result_t netvsc_vf_handle_frame(struct sk_buff **pskb)
 static int netvsc_vf_join(struct net_device *vf_netdev,
 			  struct net_device *ndev)
 {
-	struct net_device_context *ndev_ctx = netdev_priv(ndev);
+	char vf_name[IFNAMSIZ];
 	int ret;
 
 	ret = netdev_rx_handler_register(vf_netdev,
@@ -1783,23 +1782,14 @@ static int netvsc_vf_join(struct net_device *vf_netdev,
 	/* 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)
-{
-	int ret;
+	/* set the name of VF device based on upper device name */
+	snprintf(vf_name, IFNAMSIZ, "%s_vf", ndev->name);
+	ret = dev_change_name(vf_netdev, vf_name);
+	if (ret != 0)
+		netdev_warn(vf_netdev,
+			    "can not rename device: (%d)\n", ret);
 
 	/* Align MTU of VF with master */
 	ret = dev_set_mtu(vf_netdev, ndev->mtu);
@@ -1807,34 +1797,21 @@ static void __netvsc_vf_setup(struct net_device *ndev,
 		netdev_warn(vf_netdev,
 			    "unable to change mtu to %u\n", ndev->mtu);
 
+	/* If upper device is already up, bring up slave */
 	if (netif_running(ndev)) {
 		ret = dev_open(vf_netdev);
 		if (ret)
 			netdev_warn(vf_netdev,
 				    "unable to open: %d\n", ret);
 	}
-}
-
-/* Setup VF as slave of the synthetic device.
- * Runs in workqueue to avoid recursion in netlink callbacks.
- */
-static void netvsc_vf_setup(struct work_struct *w)
-{
-	struct net_device_context *ndev_ctx
-		= container_of(w, struct net_device_context, vf_takeover.work);
-	struct net_device *ndev = hv_get_drvdata(ndev_ctx->device_ctx);
-	struct net_device *vf_netdev;
-
-	if (!rtnl_trylock()) {
-		schedule_delayed_work(&ndev_ctx->vf_takeover, 0);
-		return;
-	}
 
-	vf_netdev = rtnl_dereference(ndev_ctx->vf_netdev);
-	if (vf_netdev)
-		__netvsc_vf_setup(ndev, vf_netdev);
+	netdev_info(vf_netdev, "joined to %s\n", ndev->name);
+	return 0;
 
-	rtnl_unlock();
+ upper_link_failed:
+	netdev_rx_handler_unregister(vf_netdev);
+ rx_handler_failed:
+	return ret;
 }
 
 static int netvsc_register_vf(struct net_device *vf_netdev)
@@ -1904,7 +1881,6 @@ static int netvsc_unregister_vf(struct net_device *vf_netdev)
 		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);
 
@@ -1947,7 +1923,6 @@ static int netvsc_probe(struct hv_device *dev,
 
 	spin_lock_init(&net_device_ctx->lock);
 	INIT_LIST_HEAD(&net_device_ctx->reconfig_events);
-	INIT_DELAYED_WORK(&net_device_ctx->vf_takeover, netvsc_vf_setup);
 
 	net_device_ctx->vf_stats
 		= netdev_alloc_pcpu_stats(struct netvsc_vf_pcpu_stats);
diff --git a/net/core/dev.c b/net/core/dev.c
index c7db39926769..f51358a90efa 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1238,6 +1238,7 @@ int dev_change_name(struct net_device *dev, const char *newname)
 
 	return err;
 }
+EXPORT_SYMBOL(dev_change_name);
 
 /**
  *	dev_set_alias - change ifalias of a device
-- 
2.11.0

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