bjonglez:

I've been trying to debug this regression in 18.06.8: in some circumstances, rpcd fails to start.

This is mostly visible as it breaks LuCI, see e.g. openwrt/luci#3773 or https://forum.openwrt.org/t/luci-error-after-upgrade-to-r10949-or-r10951-etc-config-luci-seems-to-be-corrupt/56880

To reproduce on 18.06.8:

• remove the ''rpcd'' section in ''/etc/config/rpcd''
• reboot (this is important)
• result: ''rpcd'' is not started, and the following log message is printed in ''logread'':

More details:

When this issue happens, it becomes impossible to start ''rpcd'' with ''procd'', even when adding back the ''rpcd'' section:

root@OpenWrt:# uci set rpcd.@rpcd[-1].socket=/var/run/ubus.sock
root@OpenWrt:# uci commit
root@OpenWrt:# PROCD_DEBUG=1 /etc/init.d/rpcd start
{ "name": "rpcd", "script": "/etc/init.d/rpcd", "instances": { "instance1": { "command": [ "/sbin/rpcd", "-s", "/var/run/ubus.sock", "-t", "30" ] } }, "triggers": [ ], "data": { } }
root@OpenWrt:# ps | grep rpc
1680 root 1200 S grep rpc


However, running ''rpcd'' manually works perfectly well (and fixes LuCI):

Workaround:

To workaround the issue, it is necessary to:

• add a ''rpcd'' section with either a ''socket'' or ''timeout'' option
• reboot

At this point, ''rpcd'' is started correctly, and everything works fine. It is even possible to delete the ''rpcd'' section and restart ''rpcd'', it will still start correctly.

Finding the root cause:

There are very few commits between 18.06.7 and 18.06.8. None of these commits is touching ''procd'' or ''rpcd''.

However, there has been a libubox fix in 82fbd85. This is currently the prime suspect: I will try to revert this commit, and also try with the further libubox fixes that have not yet been backported.