bug in nl_cache_refill?

[Brett Ciphery]

> > err code refilling route cache: -25
> > err code refilling route cache: 0
> > err code refilling route cache: -25
> > err code refilling route cache: 0
> > err code refilling route cache: 0
> > err code refilling route cache: -25
> > err code refilling route cache: 0
> > ...
> > 
> > Which comes from lib/nl.c:719, indicating an NLE_BUSY, or, -EBUSY
> > syserr.  This leaves a previously populated cache empty for a
> > (seemingly) non-critical error.  What do you think about handling
> > -NLE_BUSY inside nl_cache_refill, just as we do -NLE_DUMP_INTR?
> 
> Good catch Brett. I agree, we need catch -NLE_BUSY and restart the
> dump. Do you want to provide a patch or should I fix it?

Sure.

It was the frequency of these NLE_BUSY I found rather concerning,
approaching roughly 50% for a system with essentially stable routing
tables and link interfaces.

I'm on the road a fair bit the next few days but I'll send a patch over
early next week.

Brett