Re: [PATCH v2 bpf-next 1/2] bpf: Allow ringbuf memory to be used as map key

[Yonghong Song <yhs@xxxxxx>]

On 9/14/22 1:35 PM, Dave Marchevsky wrote:
> This patch adds support for the following pattern:
>
>    struct some_data *data = bpf_ringbuf_reserve(&ringbuf, sizeof(struct some_data, 0));
>    if (!data)
>      return;
>    bpf_map_lookup_elem(&another_map, &data->some_field);
>    bpf_ringbuf_submit(data);
>
> Currently the verifier does not consider bpf_ringbuf_reserve's
> PTR_TO_MEM | MEM_ALLOC ret type a valid key input to bpf_map_lookup_elem.
> Since PTR_TO_MEM is by definition a valid region of memory, it is safe
> to use it as a key for lookups.
>
> Signed-off-by: Dave Marchevsky <davemarchevsky@xxxxxx>

Acked-by: Yonghong Song <yhs@xxxxxx>