David Wang <00107082@xxxxxxx> wrote:
Hello,
> At 2023-09-06 00:38:02, "Daniel Xu" <dxu@xxxxxxxxx> wrote:
> >Hi David,
> >
> >On Mon, Sep 04, 2023 at 09:02:02PM +0800, David Wang wrote:
>
> >> #include <linux/in6.h>
> >>
> >> /* Responses from hook functions. */
> >> -#define NF_DROP 0
> >> -#define NF_ACCEPT 1
> >> -#define NF_STOLEN 2
> >> -#define NF_QUEUE 3
> >> -#define NF_REPEAT 4
> >> -#define NF_STOP 5 /* Deprecated, for userspace nf_queue compatibility. */
> >> -#define NF_MAX_VERDICT NF_STOP
> >> +enum {
> >> + NF_DROP = 0,
> >> + NF_ACCEPT = 1,
> >> + NF_STOLEN = 2,
> >> + NF_QUEUE = 3,
> >> + NF_REPEAT = 4,
> >> + NF_STOP = 5, /* Deprecated, for userspace nf_queue compatibility. */
> >> + NF_MAX_VERDICT = NF_STOP,
> >> +};
> >
> >Switching from macro to enum works for almost all use cases, but not
> >all. If someone if #ifdefing the symbols (which is plausible) this
> >change would break them.
> >
> >I think I've seen some other networking code define both enums and
> >macros. But it was a little ugly. Not sure if that is acceptable here or
> >not.
> >
> >[...]
> >
> >Thanks,
> >Daniel
>
>
> Thanks for the review~
> I do not have a strong reasoning to deny the possibility of breaking unexpected usage of this macros,
>
> but I also agree that it is ugly to use both enum and macro at the same time.
>
> Kind of don't know how to proceed from here now...
I was about to apply this as-is, but Pablo Neira would prefer to
keep the defines as well.
So, as a compromise, I would suggest to just *add*
/* verdicts available to BPF are exported via vmlinux.h */
enum {
NF_DROP = 0,
NF_ACCEPT = 1,
};
#define NF_DROP 0
...
This way BTF won't have the other verdicts, but ATM those
cannot be used in BPF programs anyway.
Would you mind making a new version of the patch?
Otherwise I can mangle it locally here as needed.
