linux-kernel - Re: [PATCH v3 net-next] net: filter: cleanup sk_* and bpf

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Message-ID: <20140729164226.GA6069@salvia>
Date:	Tue, 29 Jul 2014 18:42:26 +0200
From:	Pablo Neira Ayuso <pablo@...filter.org>
To:	Alexei Starovoitov <ast@...mgrid.com>
Cc:	"David S. Miller" <davem@...emloft.net>,
	Daniel Borkmann <dborkman@...hat.com>,
	Willem de Bruijn <willemb@...gle.com>,
	Kees Cook <keescook@...omium.org>,
	Network Development <netdev@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	netfilter-devel <netfilter-devel@...r.kernel.org>
Subject: Re: [PATCH v3 net-next] net: filter: cleanup sk_* and bpf_* names

On Tue, Jul 29, 2014 at 08:55:04AM -0700, Alexei Starovoitov wrote:
> > I don't think this is the right moment to add this, but we have to
> > keep in mind that something similar to this will need to be
> > accomodated in struct sk_filter at some point to avoid sloppy changes
> > that may result in reintroducing code later on.
> 
> I thought in v1 series you were arguing exactly about introducing them now...
> ok, I will drop callbacks and keep refcnt,rcu,filter_size and bpf_prog pointer
> in there. Sounds good?

Agreed.

> > Next step should be to wrap the specific bpf fields in struct
> > bpf_prog in some clean way IMO, which was partially the aim of this
> > patch.
> 
> it seems your only objection is 'rcu_head' still being there and rebasing
> on top of yours will fix it...

Almost. I just wanted to leave in place struct sk_filter for the
coming up generalization, that structure should contain the refcnt,
rcu_head and the struct bpf_prog after some of your follow up patches.
Please, also leave sk_filter_charge/uncharge/get_filter whatever will
provide the room the generalization under net/core/filter.c, not need
to move these to kernel/bpf/

After my patch (and your follow up), we don't have sloppy usage of
rcu_head for unattached filter anymore and I guess Willem is going to
same save bytes in his iptables/bpf rules given that he can directly
use bpf_prog instead of sk_filter.
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