netdev - Re: [PATCH bpf-next v5] bpf: Lift hashtab key

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Message-ID: <CAEf4BzaR8D1tHSN+s4xjqdHc1ScL_O13E7fsyYgsD=Cj8vohmQ@mail.gmail.com>
Date:   Thu, 29 Oct 2020 13:38:12 -0700
From:   Andrii Nakryiko <andrii.nakryiko@...il.com>
To:     Florian Lehner <dev@...-flo.net>
Cc:     bpf <bpf@...r.kernel.org>, Networking <netdev@...r.kernel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        john fastabend <john.fastabend@...il.com>
Subject: Re: [PATCH bpf-next v5] bpf: Lift hashtab key_size limit

On Thu, Oct 29, 2020 at 1:16 PM Florian Lehner <dev@...-flo.net> wrote:
>
> Currently key_size of hashtab is limited to MAX_BPF_STACK.
> As the key of hashtab can also be a value from a per cpu map it can be
> larger than MAX_BPF_STACK.
>
> The use-case for this patch originates to implement allow/disallow
> lists for files and file paths. The maximum length of file paths is
> defined by PATH_MAX with 4096 chars including nul.
> This limit exceeds MAX_BPF_STACK.
>
> Changelog:
>
> v5:
>  - Fix cast overflow
>
> v4:
>  - Utilize BPF skeleton in tests
>  - Rebase
>
> v3:
>  - Rebase
>
> v2:
>  - Add a test for bpf side
>
> Signed-off-by: Florian Lehner <dev@...-flo.net>
> Acked-by: John Fastabend <john.fastabend@...il.com>
> ---

LGTM.
Acked-by: Andrii Nakryiko <andrii@...nel.org>

>  kernel/bpf/hashtab.c                          | 16 +++----
>  .../selftests/bpf/prog_tests/hash_large_key.c | 43 ++++++++++++++++++
>  .../selftests/bpf/progs/test_hash_large_key.c | 44 +++++++++++++++++++
>  tools/testing/selftests/bpf/test_maps.c       |  3 +-
>  4 files changed, 94 insertions(+), 12 deletions(-)
>  create mode 100644 tools/testing/selftests/bpf/prog_tests/hash_large_key.c
>  create mode 100644 tools/testing/selftests/bpf/progs/test_hash_large_key.c
>

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