Subject: Re: [PATCH v9 tip 1/9] bpf: make internal bpf API independent of CONFIG_BPF_SYSCALL ifdefs

From: Masami Hiramatsu <[email-masked]>
Date: Sat, 21 Mar 2015 21:16:55 +0900

(2015/03/21 8:30), Alexei Starovoitov wrote:
> From: Daniel Borkmann <[email-masked]>
> 
> Socket filter code and other subsystems with upcoming eBPF support should
> not need to deal with the fact that we have CONFIG_BPF_SYSCALL defined or
> not.
> 
> Having the bpf syscall as a config option is a nice thing and I'd expect
> it to stay that way for expert users (I presume one day the default setting
> of it might change, though), but code making use of it should not care if
> it's actually enabled or not.
> 
> Instead, hide this via header files and let the rest deal with it.
> 

Looks good to me.

Reviewed-by: Masami Hiramatsu <[email-masked]>

Thank you,

> Signed-off-by: Daniel Borkmann <[email-masked]>
> Signed-off-by: Alexei Starovoitov <[email-masked]>
> ---
>  include/linux/bpf.h |   20 ++++++++++++++++----
>  1 file changed, 16 insertions(+), 4 deletions(-)
> 
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index bbfceb756452..c2e21113ecc0 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -113,8 +113,6 @@ struct bpf_prog_type_list {
>  	enum bpf_prog_type type;
>  };
>  
> -void bpf_register_prog_type(struct bpf_prog_type_list *tl);
> -
>  struct bpf_prog;
>  
>  struct bpf_prog_aux {
> @@ -129,11 +127,25 @@ struct bpf_prog_aux {
>  };
>  
>  #ifdef CONFIG_BPF_SYSCALL
> +void bpf_register_prog_type(struct bpf_prog_type_list *tl);
> +
>  void bpf_prog_put(struct bpf_prog *prog);
> +struct bpf_prog *bpf_prog_get(u32 ufd);
>  #else
> -static inline void bpf_prog_put(struct bpf_prog *prog) {}
> +static inline void bpf_register_prog_type(struct bpf_prog_type_list *tl)
> +{
> +}
> +
> +static inline struct bpf_prog *bpf_prog_get(u32 ufd)
> +{
> +	return ERR_PTR(-EOPNOTSUPP);
> +}
> +
> +static inline void bpf_prog_put(struct bpf_prog *prog)
> +{
> +}
>  #endif
> -struct bpf_prog *bpf_prog_get(u32 ufd);
> +
>  /* verify correctness of eBPF program */
>  int bpf_check(struct bpf_prog *fp, union bpf_attr *attr);
>  
> 

-- 
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Research Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: [email-masked]