ansible: osmo-gsm-tester: Make modem net ifaces persistent

Currently ofono doesn't catch network interface renaming (takes the name
at ofono startup time).
If a modem crashes, its net iface is unregistered and registered again,
and it can happen that the new name is not the same as before (for
instance, wwan8->wwan0 if wwan0 is located on another netns).

These udev rules allow creating persistent unique names to prevent modem
crashes resulting on interface name changing.

dhcpcd is known to race against udev when managing dev interfaces,
bringing them up before udev sometimes, and then udev is unable to
rename it. By denying dhcpcd from managing modem ifaces (ww* and r*
according to kernel/our rules), we get rid of this issue.

Related: OS#3881
Change-Id: Ic3ef75285aa84f9aa606562cd2f6166de186c1a6

1 files changed, 10 insertions, 0 deletions

diff --git a/ansible/roles/gsm-tester/files/70-net-setup-link-modems.rules b/ansible/roles/gsm-tester/files/70-net-setup-link-modems.rules
new file mode 100644
index 0000000..a9826e2
--- /dev/null
+++ b/ansible/roles/gsm-tester/files/70-net-setup-link-modems.rules
@@ -0,0 +1,10 @@
+SUBSYSTEM!="net", GOTO="net_setup_link_end"
+ACTION!="add", GOTO="net_setup_link_end"
+
+IMPORT{builtin}="net_id"
+
+# If dev paths are too long (too many usb hubs in the path) (>IFNAMSIZ), ID_NET_NAME_PATH is not populated.
+ENV{DEVTYPE}=="wwan", ENV{ID_NET_NAME_PATH}!="", NAME="$env{ID_NET_NAME_PATH}"
+ENV{DEVTYPE}=="wwan", ENV{ID_NET_NAME_PATH}=="", PROGRAM="/bin/sh -ec 'echo ${DEVPATH} | sha1sum | head -c14'", NAME="r$result"
+
+LABEL="net_setup_link_end"