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

[Daniel Borkmann]

On 08/29/2014 08:02 PM, Alexei Starovoitov wrote:
> On Fri, Aug 29, 2014 at 10:39 AM, Daniel Borkmann <dborkman@xxxxxxxxxx> wrote:
> > 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.
>
> It's been bugging me as well, but I suspect having it the way you
> described won't work. Mainly because we cannot do include <uapi/..>
> inside uapi/*.h, so we would need to do include <linux/bpf.h>
> inside uapi/linux/filter.h, but that will cause serious include path
> confusion. That was the reason I didn't simply do include <linux/filter.h>
> inside uapi/linux/bpf.h
>
> Also I really dislike 'ebpf' name in all lower case. If we make such header
> file name, we would need to rename all macros and function names
> to EBPF_... which I find very ugly looking. I think all good abbreviations are
> three letters :)

I don't think we would have to name defines that way, really, that would be
terrible. We can keep them simply *as is*. Not sure though why bpf.h + ebpf.h
would be that bad. ;) I haven't tried it out yet, but if we would indeed run
into a name collision, above proposal would resolve that.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/