netdev - [RFC PATCH] powerpc/pseries/mobility: notify network peers after migration

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Date:   Tue,  5 Nov 2019 18:06:34 -0600
From:   Thomas Falcon <tlfalcon@...ux.ibm.com>
To:     linuxppc-dev@...abs.org
Cc:     netdev@...r.kernel.org, nathanl@...ux.ibm.com,
        tyreld@...ux.ibm.com, msuchanek@...e.com,
        Thomas Falcon <tlfalcon@...ux.ibm.com>
Subject: [RFC PATCH] powerpc/pseries/mobility: notify network peers after migration

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@...ux.ibm.com>
---
 arch/powerpc/platforms/pseries/mobility.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/arch/powerpc/platforms/pseries/mobility.c b/arch/powerpc/platforms/pseries/mobility.c
index b571285f6c14..c1abc14cf2bb 100644
--- a/arch/powerpc/platforms/pseries/mobility.c
+++ b/arch/powerpc/platforms/pseries/mobility.c
@@ -17,6 +17,9 @@
 #include <linux/delay.h>
 #include <linux/slab.h>
 #include <linux/stringify.h>
+#include <linux/netdevice.h>
+#include <linux/rtnetlink.h>
+#include <net/net_namespace.h>
 
 #include <asm/machdep.h>
 #include <asm/rtas.h>
@@ -331,6 +334,8 @@ void post_mobility_fixup(void)
 {
 	int rc;
 	int activate_fw_token;
+	struct net_device *netdev;
+	struct net *net;
 
 	activate_fw_token = rtas_token("ibm,activate-firmware");
 	if (activate_fw_token == RTAS_UNKNOWN_SERVICE) {
@@ -371,6 +376,21 @@ 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;
 }
 
-- 
2.12.3