In article [ref] (at Tue, 27 Mar 2007 16:25:19 +0200), Thomas Graf [off-list ref] says:

* YOSHIFUJI Hideaki / ?$B5HF#1QL@ [off-list ref] 2007-03-27 22:45

quoted

When looking up route for destination with rules with
source address restrictions, we may need to find a source
address for the traffic if not given.

Out of curiosity, what sort of rules would have this flag set?
The majority of lookups don't provide a valid source address.
This new address search could become very expensive, because
none of the results are cached.

This flags is used for Mobile IPv6.

Well, for non-connected sockets on hosts, yes,
the process might not be light-weight.
But, on routers, or once the socket is connected,
source address should be always set.

This chunk won't apply to latest net-2.6.22, I've added two more
flags yesterday.

Oops,... I'll send rebased version...

--yoshfuji