Merge autopkgtest-cloud:blacklist-virtio-rng into autopkgtest-cloud:master

[Brian Murray]

Modify /etc/default/grub so that GRUB_CMDLINE_LINUX= contains "module_blacklist=virtio_rng". This needs to be done in GRUB_CMDLINE_LINUX as GRUB_CMDLINE_LINUX_DEFAULT is later set in /etc/default/grub.d/90-autopkgtest.cfg which is created by autopkgtest.

I cowboy'ed this change on one of the cloud-worker units (autopkgtest-cloud-worker/0) and created adt/ubuntu-kinetic-amd64-server-20220912.img which has the module blacklisted.

[Paride Legovini (paride)]

LGTM, the only comment I have is we're going to hit this again if the underlying issue (LP: #1989258) isn't fixed before LL, as the workaround is specific to kinetic. This can also be seen as a positive thing: if still not fixed in kernel we should bring the issue up again.

review: Approve

diff --git a/charms/focal/autopkgtest-cloud-worker/autopkgtest-cloud/worker-config-production/setup-canonical.sh b/charms/focal/autopkgtest-cloud-worker/autopkgtest-cloud/worker-config-production/setup-canonical.sh
index 1201fb2..b53dfac 100644
--- a/charms/focal/autopkgtest-cloud-worker/autopkgtest-cloud/worker-config-production/setup-canonical.sh
+++ b/charms/focal/autopkgtest-cloud-worker/autopkgtest-cloud/worker-config-production/setup-canonical.sh
@@ -25,6 +25,14 @@ if [ "$(uname -m)" = aarch64 ] && ! grep -q 'GRUB_CMDLINE_LINUX.*nohz-off' /etc/
     update-grub
 fi
 
+# work around hung tasks timeout w/ virtio_rng (LP: #1989258)
+if grep -q kinetic /etc/lsb-release; then
+    if [ "$(uname -m)" = x86_64 ] && ! grep -q 'GRUB_CMDLINE_LINUX=.*module_blacklist=virtio_rng' /etc/default/grub; then
+        sed -i '/GRUB_CMDLINE_LINUX=/ s/="\(.*\)"$/="\1 module_blacklist=virtio_rng"/' /etc/default/grub
+        update-grub
+    fi
+fi
+
 # work around broken tty on ppc64el instances (LP: #1607075)
 if [ "$(uname -m)" = ppc64le ] && [ "$(systemctl is-active keyboard-setup.service 2>/dev/null|| true)" = failed ]; then
     systemctl reset-failed keyboard-setup.service