Multicast snooping enabled bridges maintain a database for multicast
port memberships to decide which mulicast packet is supposed to
egress on which port.
This patch teaches networkd to add entries to this database manually
by adding `[BridgeMDB]` sections to `.network` configuration files.
Previously, on DHCPv4 address renewal, the old address may be removed
while the new address is not ready yet.
This also simplifies the logic of removing address and routes.
In NetworkdBridgeTests.test_bridge_configure_without_carrier of
systemd-networkd-tests.py
```
bridge99: MAC address: 2e:3a:ec:4d:d3:62
Assertion 'sd_ipv4ll_is_running(ll) == 0' failed at src/libsystemd-network/sd-ipv4ll.c:110, function int sd_ipv4ll_set_mac(sd_ipv4ll *, const struct ether_addr *)(). Ignoring.
bridge99: Could not update MAC address in IPv4LL client: Device or resource busy
```
When DHCP6 and RA are enabled, and RA does not provide any addresses,
then link may become configured state even if no address is assigned,
due to the time-lag between RA completion and DHCP reply.
This makes if DHCP is explicitly enabled, then link must have at least
one valid address to be in the configured state.
While investigating https://github.com/systemd/systemd/issues/16356, I
discovered that networkd stops the radv service before adding or updating
prefixes and then starts it again. This causes networkd to send an RA with
a router lifetime of zero, causing the routes to flap on systems receiving
the RA for a fraction of a second before radv is started again and proper
RAs are sent. That has the potential to cause issues with latency-sensitive
traffic like gaming or VoIP. This patch adds a boolean argument to the
sd_radv_stop() function to control this behavior. The zero lifetime RA is
still sent whenever radv is actually being stopped, but when it is being
restarted for a prefix update (from networkd-dhcp6.c), the final RA is no
longer sent to avoid the route flapping.
SR-IOV provides the ability to partition a single physical PCI
resource into virtual PCI functions which can then be injected in
to a VM. In the case of network VFs, SR-IOV improves north-south n
etwork performance (that is, traffic with endpoints outside the
host machine) by allowing traffic to bypass the host machine’s network stack.
I'm not sure if I understand the code correctly, but it seems that if
storig in the second set failed, we'd return with the first set having
no reference on the link object, and the link object could be freed in the
future, leaving the set with a dangling reference.
Patch contains a coccinelle script, but it only works in some cases. Many
parts were converted by hand.
Note: I did not fix errors in return value handing. This will be done separate
to keep the patch comprehensible. No functional change is intended in this
patch.
