From 7061eb8cfa902daa1ec71d23b5cddb8b4391e72b Mon Sep 17 00:00:00 2001

From: Lijun Pan <ljp@linux.ibm.com>

Date: Mon, 14 Dec 2020 15:19:28 -0600

Subject: [PATCH] net: core: introduce __netdev_notify_peers

References: bsc#1184114 ltc#192237 bsc#1183871 ltc#192139

Patch-mainline: v5.11-rc1

Git-commit: 7061eb8cfa902daa1ec71d23b5cddb8b4391e72b

There are some use cases for netdev_notify_peers in the context

when rtnl lock is already held. Introduce lockless version

of netdev_notify_peers call to save the extra code to call

	call_netdevice_notifiers(NETDEV_NOTIFY_PEERS, dev);

	call_netdevice_notifiers(NETDEV_RESEND_IGMP, dev);

After that, convert netdev_notify_peers to call the new helper.

Suggested-by: Nathan Lynch <nathanl@linux.ibm.com>

Signed-off-by: Lijun Pan <ljp@linux.ibm.com>

Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Acked-by: Michal Suchanek <msuchanek@suse.de>

---

 include/linux/netdevice.h |  1 +

 net/core/dev.c            | 22 ++++++++++++++++++++--

 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h

index 7bf167993c05..259be67644e3 100644

--- a/include/linux/netdevice.h

+++ b/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 */

diff --git a/net/core/dev.c b/net/core/dev.c

index a46334906c94..8fa739259041 100644

--- a/net/core/dev.c

+++ b/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);

-- 

2.26.2