Subject: Re: [PATCH 1/1] ipv6 addrconf: add IFA_F_NOPREFIXROUTE flag to suppress creation of IP6 routes

From: Thomas Haller <[email-masked]>
Date: Tue, 07 Jan 2014 13:14:34 +0100

On Tue, 2014-01-07 at 13:01 +0100, Hannes Frederic Sowa wrote:
> On Mon, Jan 06, 2014 at 06:29:35PM +0100, Thomas Haller wrote:
> > @@ -3662,8 +3666,10 @@ static int inet6_addr_modify(struct inet6_ifaddr *ifp, u32 ifa_flags,
> >  	if (!(ifp->flags&IFA_F_TENTATIVE))
> >  		ipv6_ifa_notify(0, ifp);
> >  
> > -	addrconf_prefix_route(&ifp->addr, ifp->prefix_len, ifp->idev->dev,
> > -			      expires, flags);
> > +	if (ifa_flags & IFA_F_NOPREFIXROUTE == 0) {
> > +		addrconf_prefix_route(&ifp->addr, ifp->prefix_len, ifp->idev->dev,
> > +				      expires, flags);
> > +	}
> 
> Actually, if we switch from IFA_F_NOPREFIXROUTE to !IFA_F_NOPREFIXROUTE we
> have to remove the prefix route, no?
> 
> Greetings,
> 
>   Hannes
> 

hi Hannes,

I am about to resent the patch, so that IFA_F_NOPREFIXROUTE is saved in
the flags of the address. Later, when deleting such address, this is
used to indicate ~not~ to delete any prefix route... just as you suggest
in your earlier email (if I understood you right).

About this suggestion now, I tend to "no". Yes, it could be sensible, on
the other hand, if user space already controls the routes (as indicated
by it's use of IFA_F_NOPREFIXROUTES), I would just leave it to the user
to clean up the wrong prefix route.

What do you think?

Thomas