what is the story on if_index allocation ?

[Luigi Rizzo]

I am a bit unclear -- how do we allocate if_index values for
network interfaces ?
I thought the strategy was allocate them sequentially, and
only reuse numbers at the top of the allocated range.
But then i see if_findindex() is quite complicated, and
seems to look for hints using resource_string_value() and
resource_find_dev() to possibly recycle old indexes below
if_index.

Can someone explain what is the goal ? Reuse a number if an
interface has the same name of a previously existing one and
the index is free ? And does it make sense, anyways, or
we could just simplify that code and just reuse the first
available entry in ifindex_table[] ?
Even the current allocation strategy does not guarantee that
indexes reflect the order of creation of interfaces, if that
is what we care about.

	cheers
	luigi