From a0dc92f46cc5a95cb7b13bb7fcfc0a095275fd40 Mon Sep 17 00:00:00 2001
From: Kairui Song <kasong@redhat.com>
Date: Mon, 12 Nov 2018 20:27:18 +0800
Subject: [PATCH] dracut-module-setup: Fix routing failure on multipath route

Currently we still don't support multipath route, when parsing multipath
route kdumpctl will wrongly consider 'nexthop' as the destination address,
and raise errors in second kernel.

When multipath route is in use, ip route output should be like this:
$ /sbin/ip route show
default via 192.168.122.1 dev ens1 proto dhcp metric 100
192.168.122.0/24 dev ens1 proto kernel scope link src 192.168.122.161 metric 100
192.168.122.8
	nexthop via 192.168.122.1 dev ens1 weight 50
	nexthop via 192.168.122.2 dev ens1 weight 5

As we don't care about HA/performance, simply use the rule with highest
weight and ignore the rest.

Signed-off-by: Kairui Song <kasong@redhat.com>
Acked-by: Baoquan He <bhe@redhat.com>
---
 dracut-module-setup.sh | 41 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 40 insertions(+), 1 deletion(-)

diff --git a/dracut-module-setup.sh b/dracut-module-setup.sh
index 2f9d762..7499678 100755
--- a/dracut-module-setup.sh
+++ b/dracut-module-setup.sh
@@ -126,7 +126,8 @@ kdump_static_ip() {
         echo -n "${_srcaddr}::${_gateway}:${_netmask}::"
     fi
 
-    /sbin/ip $_ipv6_flag route show | grep -v default | grep ".*via.* $_netdev " |\
+    /sbin/ip $_ipv6_flag route show | grep -v default |\
+    grep ".*via.* $_netdev " | grep -v "^[[:space:]]*nexthop" |\
     while read _route; do
         _target=`echo $_route | cut -d ' ' -f1`
         _nexthop=`echo $_route | cut -d ' ' -f3`
@@ -136,6 +137,44 @@ kdump_static_ip() {
         fi
         echo "rd.route=$_target:$_nexthop:$_netdev"
     done >> ${initdir}/etc/cmdline.d/45route-static.conf
+
+    kdump_handle_mulitpath_route $_netdev $_srcaddr
+}
+
+kdump_handle_mulitpath_route() {
+    local _netdev="$1" _srcaddr="$2" _ipv6_flag
+    local _target _nexthop _route _weight _max_weight _rule
+
+    if is_ipv6_address $_srcaddr; then
+        _ipv6_flag="-6"
+    fi
+
+    while IFS="" read _route; do
+        if [[ "$_route" =~ [[:space:]]+nexthop ]]; then
+            _route=$(echo "$_route" | sed -e 's/^[[:space:]]*//')
+            # Parse multipath route, using previous _target
+            [[ "$_target" == 'default' ]] && continue
+            [[ "$_route" =~ .*via.*\ $_netdev ]] || continue
+
+            _weight=`echo "$_route" | cut -d ' ' -f7`
+            if [[ "$_weight" -gt "$_max_weight" ]]; then
+                _nexthop=`echo "$_route" | cut -d ' ' -f3`
+                _max_weight=$_weight
+                if [ "x" !=  "x"$_ipv6_flag ]; then
+                    _rule="rd.route=[$_target]:[$_nexthop]:$_netdev"
+                else
+                    _rule="rd.route=$_target:$_nexthop:$_netdev"
+                fi
+            fi
+        else
+            [[ -n "$_rule" ]] && echo "$_rule"
+            _target=`echo "$_route" | cut -d ' ' -f1`
+            _rule="" _max_weight=0 _weight=0
+        fi
+    done >> ${initdir}/etc/cmdline.d/45route-static.conf\
+        < <(/sbin/ip $_ipv6_flag route show)
+
+    [[ -n $_rule ]] && echo $_rule >> ${initdir}/etc/cmdline.d/45route-static.conf
 }
 
 kdump_get_mac_addr() {