selftests: test_vxlan_under_vrf: Fix broken test case

stable inclusion
from stable-v5.10.110
commit 2165d0ebfbacdda40483eaa8ec305b6e79d2a3b3
bugzilla: https://gitee.com/openeuler/kernel/issues/I574AL

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2165d0ebfbacdda40483eaa8ec305b6e79d2a3b3

--------------------------------

[ Upstream commit b50d3b46 ]

The purpose of the last test case is to test VXLAN encapsulation and
decapsulation when the underlay lookup takes place in a non-default VRF.
This is achieved by enslaving the physical device of the tunnel to a
VRF.

The binding of the VXLAN UDP socket to the VRF happens when the VXLAN
device itself is opened, not when its physical device is opened. This
was also mentioned in the cited commit ("tests that moving the underlay
from a VRF to another works when down/up the VXLAN interface"), but the
test did something else.

Fix it by reopening the VXLAN device instead of its physical device.

Before:

 # ./test_vxlan_under_vrf.sh
 Checking HV connectivity                                           [ OK ]
 Check VM connectivity through VXLAN (underlay in the default VRF)  [ OK ]
 Check VM connectivity through VXLAN (underlay in a VRF)            [FAIL]

After:

 # ./test_vxlan_under_vrf.sh
 Checking HV connectivity                                           [ OK ]
 Check VM connectivity through VXLAN (underlay in the default VRF)  [ OK ]
 Check VM connectivity through VXLAN (underlay in a VRF)            [ OK ]

Fixes: 03f1c26b ("test/net: Add script for VXLAN underlay in a VRF")
Signed-off-by: NIdo Schimmel <idosch@nvidia.com>
Reviewed-by: NDavid Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20220324200514.1638326-1-idosch@nvidia.comSigned-off-by: NJakub Kicinski <kuba@kernel.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NYu Liao <liaoyu15@huawei.com>
Reviewed-by: NWei Li <liwei391@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

tools/testing/selftests/net/test_vxlan_under_vrf.sh

@@ -118,11 +118,11 @@ echo "[ OK ]"
 
 # Move the underlay to a non-default VRF
 ip -netns hv-1 link set veth0 vrf vrf-underlay
-ip -netns hv-1 link set veth0 down
-ip -netns hv-1 link set veth0 up
+ip -netns hv-1 link set vxlan0 down
+ip -netns hv-1 link set vxlan0 up
 ip -netns hv-2 link set veth0 vrf vrf-underlay
-ip -netns hv-2 link set veth0 down
-ip -netns hv-2 link set veth0 up
+ip -netns hv-2 link set vxlan0 down
+ip -netns hv-2 link set vxlan0 up
 
 echo -n "Check VM connectivity through VXLAN (underlay in a VRF)            "
 ip netns exec vm-1 ping -c 1 -W 1 10.0.0.2 &> /dev/null || (echo "[FAIL]"; false)