netdev - Re: [PATCH v2 1/2] bpf: remove struct bpf_prog_type

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Message-ID: <20170410022357.GB17150@ast-mbp.thefacebook.com>
Date:   Sun, 9 Apr 2017 19:23:59 -0700
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     David Miller <davem@...emloft.net>
Cc:     johannes@...solutions.net, netdev@...r.kernel.org,
        johannes.berg@...el.com
Subject: Re: [PATCH v2 1/2] bpf: remove struct bpf_prog_type_list

On Sun, Apr 09, 2017 at 06:22:36PM -0700, David Miller wrote:
> From: Johannes Berg <johannes@...solutions.net>
> Date: Fri,  7 Apr 2017 21:00:07 +0200
> 
> > From: Johannes Berg <johannes.berg@...el.com>
> > 
> > There's no need to have struct bpf_prog_type_list since
> > it just contains a list_head, the type, and the ops
> > pointer. Since the types are densely packed and not
> > actually dynamically registered, it's much easier and
> > smaller to have an array of type->ops pointer. Also
> > initialize this array statically to remove code needed
> > to initialize it.
> > 
> > Signed-off-by: Johannes Berg <johannes.berg@...el.com>
> 
> If you just don't want to list things multiple times how about:
> 
> linux/bpf_verifiers.h:
> BPF_VERIFIER(BPF_PROG_TYPE_SOCKET_FILTER, sk_filter_prog_ops)
> BPF_VERIFIER(BPF_PROG_TYPE_SCHED_CLS, tc_cls_prog_ops)
>  ...
> 
> Then in bpf.h:
> 
> #define BPF_VERIFIER(TYPE_VAL, SYM) extern const struct bpf_verifier_ops SYM;
> #include <linux/bpf_verifiers.h"
> 
> and in kernel/bpf/syscall.c:
> 
> #define BPF_VERIFIER(TYPE_VAL, SYM) [TYPE_VAL] = &SYM,
> #include <linux/bpf_verifiers.h"
> 
> or something like that.

That is great suggestion! I like it.