Re: [PATCH v1 bpf-next 3/5] bpf: Add bpf_dynptr_get_size and bpf_dynptr_get_offset

[Andrii Nakryiko <andrii.nakryiko@gmail.com>]

On Sat, Apr 8, 2023 at 8:34 PM Joanne Koong <joannelkoong@gmail.com> wrote:
>
> bpf_dynptr_get_size returns the number of useable bytes in a dynptr and
> bpf_dynptr_get_offset returns the current offset into the dynptr.
>
> Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
> ---
>  include/linux/bpf.h      |  2 +-
>  kernel/bpf/helpers.c     | 24 +++++++++++++++++++++---
>  kernel/trace/bpf_trace.c |  4 ++--
>  3 files changed, 24 insertions(+), 6 deletions(-)
>

[...]

> +__bpf_kfunc __u32 bpf_dynptr_get_size(const struct bpf_dynptr_kern *ptr)
> +{
> +       if (!ptr->data)
> +               return -EINVAL;
> +
> +       return __bpf_dynptr_get_size(ptr);
> +}
> +
> +__bpf_kfunc __u32 bpf_dynptr_get_offset(const struct bpf_dynptr_kern *ptr)

I think get_offset is actually not essential and it's hard to think
about the case where this is going to be really necessary. Let's keep
only get_size for now?


> +{
> +       if (!ptr->data)
> +               return -EINVAL;
> +
> +       return ptr->offset;
> +}
> +

[...]