Re: [PATCH bpf-next v3 3/6] xdp: Add devmap_hash map type for looking up devices by hashed index

[Yonghong Song <yhs@fb.com>]

On 7/8/19 3:55 AM, Toke Høiland-Jørgensen wrote:
> From: Toke Høiland-Jørgensen <toke@redhat.com>
> 
> A common pattern when using xdp_redirect_map() is to create a device map
> where the lookup key is simply ifindex. Because device maps are arrays,
> this leaves holes in the map, and the map has to be sized to fit the
> largest ifindex, regardless of how many devices actually are actually
> needed in the map.
> 
> This patch adds a second type of device map where the key is looked up
> using a hashmap, instead of being used as an array index. This allows maps
> to be densely packed, so they can be smaller.
> 
> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>

Acked-by: Yonghong Song <yhs@fb.com>

> ---
>   include/linux/bpf.h        |    7 ++
>   include/linux/bpf_types.h  |    1
>   include/trace/events/xdp.h |    3 -
>   include/uapi/linux/bpf.h   |    1
>   kernel/bpf/devmap.c        |  194 ++++++++++++++++++++++++++++++++++++++++++++
>   kernel/bpf/verifier.c      |    2
>   net/core/filter.c          |    9 ++
>   7 files changed, 214 insertions(+), 3 deletions(-)