some issues with rtnl_link_change waiting for completion

[Arnaud Mouiche]

Hello,

first, description of my setup:
- using latest availble git sources (commit 
4a7791eca1268e24225c33ed1c00c140a14cd955)
- linux 2.6.35 on a i686 (virtual box)

- ethernet link eth0 down when starting my application
- vlan on eth0 already set (called eth0.10)
- lo interface down

my program do:
- do "nl_socket_add_membership(sock, RTNLGRP_LINK ); " to receive 
notifications of interface going done / up
- do "nl_socket_disable_seq_check(sk);" also allow event packets with 
sequence = 0 to be received
- do" nl_socket_modify_cb" to set an own callback on link change 
notifications

- set link up on eth0 (rtnl_link_change)
- set link up on lo
- browse the list of link address (rtnl_addr_alloc_cache)


The issue is that the browse of link address shows no result at all.

Running the program with NLDBG=4 and NLCB=debug shows that "setting eth0 
up" is not waiting for receiving a  "<route/link::new>" ack, but exit at 
the first <route/link::new> event, received due to 
"nl_socket_add_membership"

there is no wait of a particular sequence (the one corresponding to our 
<route/link::new> sent to the kernel).
if "nl_socket_disable_seq_check(sk)" is not used, the wait_ack failed 
because of an error detected.

consequently, future commands also failed because of other 
<route/link::new> events (queued because of the vlan state change when 
changing the eth0 one), or because queued events with sequences will be 
incorrects.


Questions:
- Does it means that we can't use the same "struct nl_sock" to perform 
event notification and link configuration at once ?
- What is missing to use the same "struct nl_sock"

Regards,
Arnaud