Netlink developers and gurus,
While fine-tuning the handover speed for a certain L3 mobility daemon
under Linux 2.6.11.10, I stumbled into the following behavior which
intuitively does not follow the semantics of the RTMGRP_IPV4_IFADDR
group:
0) A userspace daemon process is running and listening to the broadcast
group.
1) Address is inserted to an interface (ip addr add ... at shell).
2) The daemon receives a NEWADDR message, just as is should, but the
daemon is unable to bind to the address *immediately* (actually in the
function that processes the netlink message). The result is "cannot
assign an address" from the bind call. However, if I do insert a single
nanosleep, even with an arbitrary low sleep value, before the bind
call, the bind then succeeds.
So, what is the semantics of NEWADDR? Should the address be bindable
right after receiving the message? Or is there a race-condition between
userspace and kernel that the inserted sleep helps to overcome by
letting the kernel to run again before the bind call?
TIA,
Teemu
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