Re: [PATCH net 2/5] netfilter: nf_tables: add position handle in event notification

[David Miller <davem@davemloft.net>]

From: Jakub Kicinski <kuba@kernel.org>
Date: Wed, 29 Sep 2021 19:19:53 -0700

> On Thu, 30 Sep 2021 01:04:57 +0200 Pablo Neira Ayuso wrote:
>> Add position handle to allow to identify the rule location from netlink
>> events. Otherwise, userspace cannot incrementally update a userspace
>> cache through monitoring events.
>> 
>> Skip handle dump if the rule has been either inserted (at the beginning
>> of the ruleset) or appended (at the end of the ruleset), the
>> NLM_F_APPEND netlink flag is sufficient in these two cases.
>> 
>> Handle NLM_F_REPLACE as NLM_F_APPEND since the rule replacement
>> expansion appends it after the specified rule handle.
>> 
>> Fixes: 96518518cc41 ("netfilter: add nftables")
>> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
> 
> Let me defer to Dave on this one. Krzysztof K recently provided us with
> this quote:
> 
> "One thing that does bother [Linus] is developers who send him fixes in the
> -rc2 or -rc3 time frame for things that never worked in the first place.
> If something never worked, then the fact that it doesn't work now is not
> a regression, so the fixes should just wait for the next merge window.
> Those fixes are, after all, essentially development work."
> 
> 	https://lwn.net/Articles/705245/
> 
> Maybe the thinking has evolved since, but this patch strikes me as odd.
> We forgot to put an attribute in netlink 8 years ago, and suddenly it's
> urgent to fill it in?  Something does not connect for me, certainly the
> commit message should have explained things better...

Agreed.