Phil Sutter <phil@xxxxxx> wrote: > On Mon, Jul 22, 2019 at 02:56:33PM +0200, Florian Westphal wrote: > > Phil Sutter <phil@xxxxxx> wrote: > > > On Mon, Jul 22, 2019 at 02:17:47PM +0200, Florian Westphal wrote: > > > > Phil Sutter <phil@xxxxxx> wrote: > > > > > use for "no data available" situations. This whole attempt feels a bit > > > > > futile. Maybe we should introduce something to signal "no value" so that > > > > > cmp expression will never match for '==' and always for '!='? Not sure > > > > > how to realize this via registers. Also undecided about '<' and '>' ops. > > > > > > > > Whats the point? > > > > > > IIRC, Pablo's demand for not aborting in nft_meta in case of > > > insufficient data was to insert a value into dreg which will never > > > match. I think the idea was to avoid accidental matching in situations > > > where a match doesn't make sense. > > > > I think the only contraint is that it must not overlap with a > > legitimate ifindex. > > > > But 0 cannot occur, so 'meta iif 0' will only match in case no input > > interface existed -- I think thats fine and might even be desired. > > OK, so we just drop my patch to reject ifindex 0 from userspace to keep > fib working? > > [...] > > I would propose to go with '0' dreg for ifindex, "" for name and leave > > rest as-is. > > My kernel patch also changes iftype to set ARPHRD_VOID and ifkind to set > an empty string as well. I would keep both with current semantics, i.e. 'break'/no match until we get more evidence that we need this ARPHDR_VOID store. For iifkind, I am not sure. Perhaps leave it as-is? Kernel doesn't allow "" iifname (so we can reuse it for 'no interface'), but what about ifkind? > For iftype, I also sent a userspace patch to disallow ARPHRD_VOID. Do > you think it should be dropped as well? I think we should leave userspace alone.
