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From:   Hao Luo <haoluo@google.com>
Date:   Wed, 6 Jul 2022 16:01:42 -0700
Message-ID: <CA+khW7gY5qAqP+EsHzEqrAk5OFKdR4Fhy76v_5WN+0ko+vkgsA@mail.gmail.com>
Subject: Re: [PATCH v2 bpf-next 1/2] bpf: add a ksym BPF iterator
To:     Alan Maguire <alan.maguire@oracle.com>
Cc:     ast@kernel.org, andrii@kernel.org, daniel@iogearbox.net,
        kafai@fb.com, songliubraving@fb.com, yhs@fb.com,
        john.fastabend@gmail.com, kpsingh@kernel.org, jolsa@kernel.org,
        mhiramat@kernel.org, akpm@linux-foundation.org, void@manifault.com,
        swboyd@chromium.org, ndesaulniers@google.com,
        9erthalion6@gmail.com, kennyyu@fb.com, geliang.tang@suse.com,
        kuniyu@amazon.co.jp, bpf@vger.kernel.org,
        linux-kernel@vger.kernel.org
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On Fri, Jul 1, 2022 at 2:28 AM Alan Maguire <alan.maguire@oracle.com> wrote:
>
> add a "ksym" iterator which provides access to a "struct kallsym_iter"
> for each symbol.  Intent is to support more flexible symbol parsing
> as discussed in [1].
>
> [1] https://lore.kernel.org/all/YjRPZj6Z8vuLeEZo@krava/
>
> Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
> Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
> ---
>  kernel/kallsyms.c | 89 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 89 insertions(+)
>
> diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
> index fbdf8d3..8b662da 100644
> --- a/kernel/kallsyms.c
> +++ b/kernel/kallsyms.c
> @@ -30,6 +30,7 @@
[...]
> +
> +static struct bpf_iter_reg ksym_iter_reg_info = {
> +       .target                 = "ksym",
> +       .ctx_arg_info_size      = 1,
> +       .ctx_arg_info           = {
> +               { offsetof(struct bpf_iter__ksym, ksym),
> +                 PTR_TO_BTF_ID_OR_NULL },
> +       },
> +       .seq_info               = &ksym_iter_seq_info,
> +};

It would be great to allow cond_resched() while iterating. Disabling
resched is unnecessary for iterating ksyms IMO.

.feature = BPF_ITER_RESCHED,

Hao

> +
[...]
> --
> 1.8.3.1
>