From 3a8d2b61ba71613daece4650dccaa745e0a3101a Mon Sep 17 00:00:00 2001
From: Thomas Falcon <tlfalcon@linux.ibm.com>
Date: Tue, 5 Nov 2019 18:06:34 -0600
Subject: [PATCH] powerpc/pseries/mobility: notify network peers after
 migration

References: bsc#1152631 ltc#181798
Patch-mainline: submitted https://patchwork.ozlabs.org/patch/1190589/

After a migration, it is necessary to send a gratuitous ARP
from all running interfaces so that the rest of the network
is aware of its new location. However, some supported network
devices are unaware that they have been migrated. To avoid network
interruptions and other unwanted behavior, force a GARP on all
valid, running interfaces as part of the post_mobility_fixup
routine.

Signed-off-by: Thomas Falcon <tlfalcon@linux.ibm.com>
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
 arch/powerpc/platforms/pseries/mobility.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/arch/powerpc/platforms/pseries/mobility.c b/arch/powerpc/platforms/pseries/mobility.c
--- a/arch/powerpc/platforms/pseries/mobility.c
+++ b/arch/powerpc/platforms/pseries/mobility.c
@@ -19,6 +19,9 @@
 #include <linux/device.h>
 #include <linux/delay.h>
 #include <linux/slab.h>
+#include <linux/netdevice.h>
+#include <linux/rtnetlink.h>
+#include <net/net_namespace.h>
 
 #include <asm/machdep.h>
 #include <asm/rtas.h>
@@ -299,6 +302,8 @@ int pseries_devicetree_update(s32 scope)
 void post_mobility_fixup(void)
 {
 	int rc;
+	struct net_device *netdev;
+	struct net *net;
 
 	rtas_activate_firmware();
 
@@ -326,6 +331,22 @@ void post_mobility_fixup(void)
 	/* Possibly switch to a new RFI flush type */
 	pseries_setup_rfi_flush();
 
+	/* need to force a gratuitous ARP on running interfaces */
+	rtnl_lock();
+	for_each_net(net) {
+		for_each_netdev(net, netdev) {
+			if (netif_device_present(netdev) &&
+			    netif_running(netdev) &&
+			    !(netdev->flags & (IFF_NOARP | IFF_LOOPBACK))) {
+				call_netdevice_notifiers(NETDEV_NOTIFY_PEERS,
+							 netdev);
+				call_netdevice_notifiers(NETDEV_RESEND_IGMP,
+							 netdev);
+			}
+		}
+	}
+	rtnl_unlock();
+
 	return;
 }