From: "Matwey V. Kornilov" <matwey@sai.msu.ru>
Date: Fri, 2 Nov 2018 21:19:36 +0300
Subject: net: core: netpoll: Enable netconsole IPv6 link local address
Patch-mainline: v4.20-rc2
Git-commit: d016b4a3562b745fd9fa387a47d8de62ccd7e241
References: bsc#1109837

There is no reason to discard using source link local address when
remote netconsole IPv6 address is set to be link local one.

The patch allows administrators to use IPv6 netconsole without
explicitly configuring source address:

    netconsole=@/,@fe80::5054:ff:fe2f:6012/

Signed-off-by: Matwey V. Kornilov <matwey@sai.msu.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 net/core/netpoll.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -719,7 +719,8 @@ int netpoll_setup(struct netpoll *np)
 
 				read_lock_bh(&idev->lock);
 				list_for_each_entry(ifp, &idev->addr_list, if_list) {
-					if (ipv6_addr_type(&ifp->addr) & IPV6_ADDR_LINKLOCAL)
+					if (!!(ipv6_addr_type(&ifp->addr) & IPV6_ADDR_LINKLOCAL) !=
+					    !!(ipv6_addr_type(&np->remote_ip.in6) & IPV6_ADDR_LINKLOCAL))
 						continue;
 					np->local_ip.in6 = ifp->addr;
 					err = 0;