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

[Ido Schimmel]

On Sun, Mar 26, 2023 at 05:41:06PM +0200, Hans Schultz wrote:
> On Mon, Mar 20, 2023 at 10:44, Ido Schimmel <idosch at 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