Re: [PATCH v2 net-next 6/6] selftests: forwarding: add dynamic FDB test

Ido Schimmel
2023-03-28T16:40:29Z

On Sun, Mar 26, 2023 at 05:41:06PM +0200, Hans Schultz wrote:
> On Mon, Mar 20, 2023 at 10:44, Ido Schimmel <idosch@nvidia.com> wrote:
> >> + $MZ $swp1 -c 1 -p 128 -t udp "sp=54321,dp=12345" \
> >> + -a $mac -b `mac_get $h2` -A 192.0.2.1 -B 192.0.2.2 -q
> >> + tc_check_packets "dev $swp2 egress" 1 1
> >> + check_fail $? "Dynamic FDB entry did not age out"
> >
> > Shouldn't this be check_err()? After the FDB entry was aged you want to
> > make sure that packets received via $swp1 with SMAC being $mac are no
> > longer forwarded by the bridge.
>
> I was thinking that check_fail() will pass when tc_check_packets() does
> not see any packets, thus the test passing here when no packets are forwarded?

What do you mean by "I was *thinking*"? How is it possible that you are
submitting a selftest that you didn't bother running?!

I see you trimmed my earlier question: "Does this actually work?"

I tried it and it passed:

# ./bridge_locked_port.sh
TEST: Locked port ipv4 [ OK ]
TEST: Locked port ipv6 [ OK ]
TEST: Locked port vlan [ OK ]
TEST: Locked port MAB [ OK ]
TEST: Locked port MAB roam [ OK ]
TEST: Locked port MAB configuration [ OK ]
TEST: Locked port MAB FDB flush [ OK ]

And I couldn't understand how that's even possible. Then I realized that
the entire test is dead code because the patch is missing this
fundamental hunk:

```
diff --git a/tools/testing/selftests/net/forwarding/bridge_locked_port.sh b/tools/testing/selftests/net/forwarding/bridge_locked_port.sh
index dbc7017fd45d..5bf6b2aa1098 100755
--- a/tools/testing/selftests/net/forwarding/bridge_locked_port.sh
+++ b/tools/testing/selftests/net/forwarding/bridge_locked_port.sh
@@ -9,6 +9,7 @@ ALL_TESTS="
locked_port_mab_roam
locked_port_mab_config
locked_port_mab_flush
+ locked_port_dyn_fdb
"

NUM_NETIFS=4
```

Which tells me that you didn't even try running it once. Now the test
failed as I expected:

# ./bridge_locked_port.sh
TEST: Locked port ipv4 [ OK ]
TEST: Locked port ipv6 [ OK ]
TEST: Locked port vlan [ OK ]
TEST: Locked port MAB [ OK ]
TEST: Locked port MAB roam [ OK ]
TEST: Locked port MAB configuration [ OK ]
TEST: Locked port MAB FDB flush [ OK ]
TEST: Locked port dyn FDB [FAIL]
Packet not seen on egress after adding dynamic FDB

Fixed by:

```
@@ -336,7 +337,7 @@ locked_port_dyn_fdb()
tc filter add dev $swp2 egress protocol ip pref 1 handle 1 flower \
dst_ip 192.0.2.2 ip_proto udp dst_port 12345 action pass

- $MZ $swp1 -c 1 -p 128 -t udp "sp=54321,dp=12345" \
+ $MZ $h1 -c 1 -p 128 -t udp "sp=54321,dp=12345" \
-a $mac -b `mac_get $h2` -A 192.0.2.1 -B 192.0.2.2 -q
tc_check_packets "dev $swp2 egress" 1 1
check_err $? "Packet not seen on egress after adding dynamic FDB"
```

Ran it again and it failed because of the second issue I pointed out:

# ./bridge_locked_port.sh
TEST: Locked port ipv4 [ OK ]
TEST: Locked port ipv6 [ OK ]
TEST: Locked port vlan [ OK ]
TEST: Locked port MAB [ OK ]
TEST: Locked port MAB roam [ OK ]
TEST: Locked port MAB configuration [ OK ]
TEST: Locked port MAB FDB flush [ OK ]
TEST: Locked port dyn FDB [FAIL]
Dynamic FDB entry did not age out

Fixed by:

```
@@ -346,7 +347,7 @@ locked_port_dyn_fdb()
$MZ $swp1 -c 1 -p 128 -t udp "sp=54321,dp=12345" \
-a $mac -b `mac_get $h2` -A 192.0.2.1 -B 192.0.2.2 -q
tc_check_packets "dev $swp2 egress" 1 1
- check_fail $? "Dynamic FDB entry did not age out"
+ check_err $? "Dynamic FDB entry did not age out"

ip link set dev br0 type bridge ageing_time $ageing_time
bridge link set dev $swp1 learning off locked off
```

# ./bridge_locked_port.sh
TEST: Locked port ipv4 [ OK ]
TEST: Locked port ipv6 [ OK ]
TEST: Locked port vlan [ OK ]
TEST: Locked port MAB [ OK ]
TEST: Locked port MAB roam [ OK ]
TEST: Locked port MAB configuration [ OK ]
TEST: Locked port MAB FDB flush [ OK ]
TEST: Locked port dyn FDB [ OK ]

Sigh