Merge branch 'locked-version-of-netdev_notify_peers'

Lijun Pan says:

====================
add a locked version of netdev_notify_peers

This series introduce the lockless version of netdev_notify_peers
and then apply it to the relevant drivers.

In v1, a more appropriate name __netdev_notify_peers is used;
netdev_notify_peers is converted to call the new helper.
In v2, patch 3 calls the new helper where notify variable used
to be set true.
====================

Link: https://lore.kernel.org/r/20201214211930.80778-1-ljp@linux.ibm.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/ibm/ibmvnic.c

@@ -2171,10 +2171,8 @@ static int do_reset(struct ibmvnic_adapter *adapter,
 		napi_schedule(&adapter->napi[i]);
 
 	if (adapter->reset_reason == VNIC_RESET_FAILOVER ||
-	    adapter->reset_reason == VNIC_RESET_MOBILITY) {
-		call_netdevice_notifiers(NETDEV_NOTIFY_PEERS, netdev);
-		call_netdevice_notifiers(NETDEV_RESEND_IGMP, netdev);
-	}
+	    adapter->reset_reason == VNIC_RESET_MOBILITY)
+		__netdev_notify_peers(netdev);
 
 	rc = 0;
 
@@ -2249,8 +2247,7 @@ static int do_hard_reset(struct ibmvnic_adapter *adapter,
 		goto out;
 	}
 
-	call_netdevice_notifiers(NETDEV_NOTIFY_PEERS, netdev);
-	call_netdevice_notifiers(NETDEV_RESEND_IGMP, netdev);
+	__netdev_notify_peers(netdev);
 out:
 	/* restore adapter state if reset failed */
 	if (rc)

drivers/net/hyperv/netvsc_drv.c

@@ -2050,11 +2050,11 @@ static void netvsc_link_change(struct work_struct *w)
 		container_of(w, struct net_device_context, dwork.work);
 	struct hv_device *device_obj = ndev_ctx->device_ctx;
 	struct net_device *net = hv_get_drvdata(device_obj);
+	unsigned long flags, next_reconfig, delay;
+	struct netvsc_reconfig *event = NULL;
 	struct netvsc_device *net_device;
 	struct rndis_device *rdev;
-	struct netvsc_reconfig *event = NULL;
-	bool notify = false, reschedule = false;
-	unsigned long flags, next_reconfig, delay;
+	bool reschedule = false;
 
 	/* if changes are happening, comeback later */
 	if (!rtnl_trylock()) {
@@ -2103,7 +2103,7 @@ static void netvsc_link_change(struct work_struct *w)
 			netif_carrier_on(net);
 			netvsc_tx_enable(net_device, net);
 		} else {
-			notify = true;
+			__netdev_notify_peers(net);
 		}
 		kfree(event);
 		break;
@@ -2132,9 +2132,6 @@ static void netvsc_link_change(struct work_struct *w)
 
 	rtnl_unlock();
 
-	if (notify)
-		netdev_notify_peers(net);
-
 	/* link_watch only sends one notification with current state per
 	 * second, handle next reconfig event in 2 seconds.
 	 */

include/linux/netdevice.h

@@ -4547,6 +4547,7 @@ void __dev_set_rx_mode(struct net_device *dev);
 int dev_set_promiscuity(struct net_device *dev, int inc);
 int dev_set_allmulti(struct net_device *dev, int inc);
 void netdev_state_change(struct net_device *dev);
+void __netdev_notify_peers(struct net_device *dev);
 void netdev_notify_peers(struct net_device *dev);
 void netdev_features_change(struct net_device *dev);
 /* Load a device via the kmod */

net/core/dev.c

@@ -1456,6 +1456,25 @@ void netdev_state_change(struct net_device *dev)
 }
 EXPORT_SYMBOL(netdev_state_change);
 
+/**
+ * __netdev_notify_peers - notify network peers about existence of @dev,
+ * to be called when rtnl lock is already held.
+ * @dev: network device
+ *
+ * Generate traffic such that interested network peers are aware of
+ * @dev, such as by generating a gratuitous ARP. This may be used when
+ * a device wants to inform the rest of the network about some sort of
+ * reconfiguration such as a failover event or virtual machine
+ * migration.
+ */
+void __netdev_notify_peers(struct net_device *dev)
+{
+	ASSERT_RTNL();
+	call_netdevice_notifiers(NETDEV_NOTIFY_PEERS, dev);
+	call_netdevice_notifiers(NETDEV_RESEND_IGMP, dev);
+}
+EXPORT_SYMBOL(__netdev_notify_peers);
+
 /**
  * netdev_notify_peers - notify network peers about existence of @dev
  * @dev: network device
@@ -1469,8 +1488,7 @@ EXPORT_SYMBOL(netdev_state_change);
 void netdev_notify_peers(struct net_device *dev)
 {
 	rtnl_lock();
-	call_netdevice_notifiers(NETDEV_NOTIFY_PEERS, dev);
-	call_netdevice_notifiers(NETDEV_RESEND_IGMP, dev);
+	__netdev_notify_peers(dev);
 	rtnl_unlock();
 }
 EXPORT_SYMBOL(netdev_notify_peers);