new file mode 100755
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+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# Validate cached routes in fib{6}_nh that is used by multiple prefixes.
+# Validate a different # exception is generated in h0 for each remote host.
+#
+# h1
+# /
+# h0 - r1 - h2
+# \
+# h3
+#
+# routing in h0 to hN is done with nexthop objects.
+
+PAUSE_ON_FAIL=no
+VERBOSE=0
+
+################################################################################
+# helpers
+
+log_test()
+{
+ local rc=$1
+ local expected=$2
+ local msg="$3"
+
+ if [ ${rc} -eq ${expected} ]; then
+ printf "TEST: %-60s [ OK ]\n" "${msg}"
+ nsuccess=$((nsuccess+1))
+ else
+ ret=1
+ nfail=$((nfail+1))
+ printf "TEST: %-60s [FAIL]\n" "${msg}"
+ if [ "${PAUSE_ON_FAIL}" = "yes" ]; then
+ echo
+ echo "hit enter to continue, 'q' to quit"
+ read a
+ [ "$a" = "q" ] && exit 1
+ fi
+ fi
+
+ [ "$VERBOSE" = "1" ] && echo
+}
+
+run_cmd()
+{
+ local cmd="$*"
+ local out
+ local rc
+
+ if [ "$VERBOSE" = "1" ]; then
+ echo "COMMAND: $cmd"
+ fi
+
+ out=$(eval $cmd 2>&1)
+ rc=$?
+ if [ "$VERBOSE" = "1" -a -n "$out" ]; then
+ echo "$out"
+ fi
+
+ [ "$VERBOSE" = "1" ] && echo
+
+ return $rc
+}
+
+################################################################################
+# config
+
+create_ns()
+{
+ local ns=${1}
+
+ ip netns del ${ns} 2>/dev/null
+
+ ip netns add ${ns}
+ ip -netns ${ns} addr add 127.0.0.1/8 dev lo
+ ip -netns ${ns} link set lo up
+
+ ip netns exec ${ns} sysctl -q -w net.ipv6.conf.all.keep_addr_on_down=1
+ case ${ns} in
+ h*)
+ ip netns exec $ns sysctl -q -w net.ipv6.conf.all.forwarding=0
+ ;;
+ r*)
+ ip netns exec $ns sysctl -q -w net.ipv4.ip_forward=1
+ ip netns exec $ns sysctl -q -w net.ipv6.conf.all.forwarding=1
+ ;;
+ esac
+}
+
+setup()
+{
+ local ns
+ local i
+
+ #set -e
+
+ for ns in h0 r1 h1 h2 h3
+ do
+ create_ns ${ns}
+ done
+
+ #
+ # create interconnects
+ #
+
+ for i in 0 1 2 3
+ do
+ ip -netns h${i} li add eth0 type veth peer name r1h${i}
+ ip -netns h${i} li set eth0 up
+ ip -netns h${i} li set r1h${i} netns r1 name eth${i} up
+
+ ip -netns h${i} addr add dev eth0 172.16.10${i}.1/24
+ ip -netns h${i} -6 addr add dev eth0 2001:db8:10${i}::1/64
+ ip -netns r1 addr add dev eth${i} 172.16.10${i}.254/24
+ ip -netns r1 -6 addr add dev eth${i} 2001:db8:10${i}::64/64
+ done
+
+ ip -netns h0 nexthop add id 4 via 172.16.100.254 dev eth0
+ ip -netns h0 nexthop add id 6 via 2001:db8:100::64 dev eth0
+
+ # routing from h0 to h1-h3 and back
+ for i in 1 2 3
+ do
+ ip -netns h0 ro add 172.16.10${i}.0/24 nhid 4
+ ip -netns h${i} ro add 172.16.100.0/24 via 172.16.10${i}.254
+
+ ip -netns h0 -6 ro add 2001:db8:10${i}::/64 nhid 6
+ ip -netns h${i} -6 ro add 2001:db8:100::/64 via 2001:db8:10${i}::64
+ done
+
+ if [ "$VERBOSE" = "1" ]; then
+ echo
+ echo "host 1 config"
+ ip -netns h0 li sh
+ ip -netns h0 ro sh
+ ip -netns h0 -6 ro sh
+ fi
+
+ #set +e
+}
+
+cleanup()
+{
+ for n in h1 r1 h2 h3 h4
+ do
+ ip netns del ${n} 2>/dev/null
+ done
+}
+
+change_mtu()
+{
+ local hostid=$1
+ local mtu=$2
+
+ run_cmd ip -netns h${hostid} li set eth0 mtu ${mtu}
+ run_cmd ip -netns r1 li set eth${hostid} mtu ${mtu}
+}
+
+################################################################################
+# validate exceptions
+
+validate_v4_exception()
+{
+ local i=$1
+ local mtu=$2
+ local ping_sz=$3
+ local dst="172.16.10${i}.1"
+ local h0=172.16.100.1
+ local r1=172.16.100.254
+ local rc
+
+ if [ ${ping_sz} != "0" ]; then
+ run_cmd ip netns exec h0 ping -s ${ping_sz} -c5 -w5 ${dst}
+ fi
+
+ if [ "$VERBOSE" = "1" ]; then
+ echo "Route get"
+ ip -netns h0 ro get ${dst}
+ echo "Searching for:"
+ echo " cache .* mtu ${mtu}"
+ echo
+ fi
+
+ ip -netns h0 ro get ${dst} | \
+ grep -q "cache .* mtu ${mtu}"
+ rc=$?
+
+ log_test $rc 0 "IPv4: host 0 to host ${i}, mtu ${mtu}"
+}
+
+validate_v6_exception()
+{
+ local i=$1
+ local mtu=$2
+ local ping_sz=$3
+ local dst="2001:db8:10${i}::1"
+ local h0=2001:db8:100::1
+ local r1=2001:db8:100::64
+ local rc
+
+ if [ ${ping_sz} != "0" ]; then
+ run_cmd ip netns exec h0 ping6 -s ${ping_sz} -c5 -w5 ${dst}
+ fi
+
+ if [ "$VERBOSE" = "1" ]; then
+ echo "Route get"
+ ip -netns h0 -6 ro get ${dst}
+ echo "Searching for:"
+ echo " ${dst} from :: via ${r1} dev eth0 src ${h0} .* mtu ${mtu}"
+ echo
+ fi
+
+ ip -netns h0 -6 ro get ${dst} | \
+ grep -q "${dst} from :: via ${r1} dev eth0 src ${h0} .* mtu ${mtu}"
+ rc=$?
+
+ log_test $rc 0 "IPv6: host 0 to host ${i}, mtu ${mtu}"
+}
+
+################################################################################
+# main
+
+while getopts :pv o
+do
+ case $o in
+ p) PAUSE_ON_FAIL=yes;;
+ v) VERBOSE=1;;
+ esac
+done
+
+cleanup
+setup
+sleep 2
+
+cpus=$(cat /sys/devices/system/cpu/online)
+cpus="$(seq ${cpus/-/ })"
+ret=0
+for i in 1 2 3
+do
+ # generate a cached route per-cpu
+ for c in ${cpus}; do
+ run_cmd taskset -c ${c} ip netns exec h0 ping -c1 -w1 172.16.10${i}.1
+ [ $? -ne 0 ] && printf "\nERROR: ping to h${i} failed\n" && ret=1
+
+ run_cmd taskset -c ${c} ip netns exec h0 ping6 -c1 -w1 2001:db8:10${i}::1
+ [ $? -ne 0 ] && printf "\nERROR: ping6 to h${i} failed\n" && ret=1
+
+ [ $ret -ne 0 ] && break
+ done
+ [ $ret -ne 0 ] && break
+done
+
+if [ $ret -eq 0 ]; then
+ # generate different exceptions in h0 for h1, h2 and h3
+ change_mtu 1 1300
+ validate_v4_exception 1 1300 1350
+ validate_v6_exception 1 1300 1350
+ echo
+
+ change_mtu 2 1350
+ validate_v4_exception 2 1350 1400
+ validate_v6_exception 2 1350 1400
+ echo
+
+ change_mtu 3 1400
+ validate_v4_exception 3 1400 1450
+ validate_v6_exception 3 1400 1450
+ echo
+
+ validate_v4_exception 1 1300 0
+ validate_v6_exception 1 1300 0
+ echo
+
+ validate_v4_exception 2 1350 0
+ validate_v6_exception 2 1350 0
+ echo
+
+ validate_v4_exception 3 1400 0
+ validate_v6_exception 3 1400 0
+
+ # targeted deletes to trigger cleanup paths in kernel
+ ip -netns h0 ro del 172.16.102.0/24 nhid 4
+ ip -netns h0 -6 ro del 2001:db8:102::/64 nhid 6
+
+ ip -netns h0 nexthop del id 4
+ ip -netns h0 nexthop del id 6
+fi
+
+cleanup