Subject: Re: [PATCH v8 net-next 2/2] net: filter: split filter.h and expose eBPF to user space

From: Daniel Borkmann <[email-masked]>
Date: Fri, 29 Aug 2014 19:39:03 +0200

On 08/27/2014 10:37 PM, Alexei Starovoitov wrote:
> allow user space to generate eBPF programs
>
> uapi/linux/bpf.h: eBPF instruction set definition
>
> linux/filter.h: the rest

Very sorry for being late, but just a thought since we're touching user
space headers anyway ...

Wouldn't it be more consistent to have it organized as follows ...

  - uapi/linux/bpf.h    : classic BPF instruction set parts only
  - uapi/linux/ebpf.h   : eBPF instruction set definition (which also
                          includes uapi/linux/bpf.h though)
... and have ...

  - uapi/linux/filter.h : just include uapi/linux/bpf.h but rest is empty

That way, it would be more consistent ...

Old legacy application can stay with linux/filter.h; new applications
based on their needs can choose between linux/{e,}bpf.h and in the kernel,
we can just include linux/ebpf.h.

Right now, it seems, an eBPF user space program would need to include
2 header files in user space (linux/filter.h, linux/bpf.h) which I find
a bit confusing.

If you want, I could also take care of that later, but just thinking out
loudly ...

> This patch only moves macro definitions, but practically it freezes existing
> eBPF instruction set, though new instructions can still be added in the future.
>
> These eBPF definitions cannot go into uapi/linux/filter.h, since the names
> may conflict with existing applications.
>
> Full eBPF ISA description is in Documentation/networking/filter.txt
>
> Signed-off-by: Alexei Starovoitov <[email-masked]>