[LEDE-DEV] Problem with iwinfo rpcd plugin and nl80211 (CONFIG_PACKAGE_rpcd-mod-iwinfo=m CONFIG_PACKAGE_rpcd-mod-lxc=y)

[Rafał Miłecki]

I've found a problem with iwinfo that appears only with a very specific config.

What happens:
ubus call iwinfo info '{ "device": "wlan0" }'
Above call fails to get interface details using nl80211 and fallbacks
to the wext.
My last debugging attempt pointed to nlmsg_alloc() returning NULL
which sounds more like ABI problem rather than malloc failing.

Note:
Using iwinfo CLI (iwinfo wlan0 info) gets interface info over nl80211
successfully.

Steps to reproduce:

1) Compile image with:
CONFIG_PACKAGE_lxc=y
CONFIG_PACKAGE_rpcd=y
CONFIG_PACKAGE_rpcd-mod-iwinfo=m
CONFIG_PACKAGE_rpcd-mod-lxc=y
(this is pretty important - the only combination I'm aware of triggering it)

2) Copy iwinfo plugin to the device:
scp ./bin/packages/arm_cortex-a9/base/rpcd-mod-iwinfo_2016-12-03-0577cfc1-1_arm_cortex-a9.ipk
root at 192.168.1.1:/tmp/

3) Install it on device
opkg install /tmp/*ipk

4) Restart rpcd:
/etc/init.d/rpcd restart

5) Call iwinfo:
ubus call iwinfo info '{ "device": "wlan0" }'

-- 
Rafał