running custom commands during sysupgrade -

[Sven Roederer]

Hi,

based on my setup for some 8/32 MB devices I'd like to run a custom script 
before / during sysupgrade.  The main task of the script should be to free 
additional RAM, as I suspect some soft-bricks and aborted upgrades to a OOM-
situation.

To me the /lib/upgrade folder seems a good place to add such scripts, as the 
*.sh files there will be sourced already, So additional patching is not 
required.

My problem is: adding a script 
--------------------------
root at gib-mir-einen-namen:~# cat /lib/upgrade/freifunk-berlin_freeup-ram.sh 
ffberlin_freeup_ram() {
  # remove LuCI-caches
  rm >/dev/null -f /tmp/luci-indexcache*
  rm >/dev/null -rf /tmp/luci-modulecache
}
ffberlin_freeup_ram
---------------------------------
works as expected. The files are delete the the firmware gets flashed. But 
just adding  a "ifdown" or "/etc/init.d/<service> stop" make the upgarde fail
-------------------------------
root at gib-mir-einen-namen:~# cat /lib/upgrade/freifunk-berlin_freeup-ram.sh 
ffberlin_freeup_ram() {
  # stop uhttpd and luci
  /etc/init.d/uhttpd stop
  # remove LuCI-caches
  rm >/dev/null -f /tmp/luci-indexcache*
  rm >/dev/null -rf /tmp/luci-modulecache
}
ffberlin_freeup_ram
-----------------------------------

The Upgrade starts as expected and runs up to

Saving config files...
Commencing upgrade. Closing all shell sessions.

and then times out. on the serial console I can see that the board just 
reboots after some time.  Normally it will do:

Watchdog handover: fd=3
- watchdog -
killall: telnetd: no process killed
killall: ash: no process killed
Sending TERM to remaining processes ... netifd odhcpd uhttpd udhcpc odhcp6c 
ntpd dnsmasq pingcheck crond ubusd askfirst urngd logd rpcd hostapd 
Sending KILL to remaining processes ... netifd uhttpd dnsmasq pingcheck sh sh 
rpcd netifd uhttpd dnsmasq sh rpcd rpcd 
Switching to ramdisk...
Performing system upgrade...
Unlocking firmware ...

Writing from <stdin> to firmware ...     
Appending jffs2 data from /tmp/sysupgrade.tgz to firmware..
    
Upgrade completed
Rebooting system...
umount: can't unmount /dev: Resource busy
umount: can't unmount /tmp: Resource busy
[  343.465535] reboot: Restarting system


Any idea what is causing this behavior?
Is my idea a totally wrong approach?


Thanks Sven.