linux-kernel - Re: [PATCH bpf-next v1 1/8] bpf: Introduce pseudo_btf

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Message-ID: <CA+khW7hGGCWkjqb_TNSQvpN-=4K==dtjF4fwUOf3zd8eoON5nw@mail.gmail.com>
Date:   Thu, 20 Aug 2020 19:22:15 -0700
From:   Hao Luo <haoluo@...gle.com>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:     Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@...r.kernel.org>, Shuah Khan <shuah@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Andrii Nakryiko <andriin@...com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>,
        Quentin Monnet <quentin@...valent.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>, Andrey Ignatov <rdna@...com>,
        Jakub Sitnicki <jakub@...udflare.com>
Subject: Re: [PATCH bpf-next v1 1/8] bpf: Introduce pseudo_btf_id

On Thu, Aug 20, 2020 at 2:53 PM Alexei Starovoitov
<alexei.starovoitov@...il.com> wrote:
>
> Why did you choose to do it during main do_check() walk instead of this pre-pass ?
> check_ld_imm() can be called multiple times for the same insn,
> so it's faster and less surprising to do it during replace_map_fd_with_map_ptr().
> BTF needs to be parsed first, of course.
> You can either move check_btf_info() before replace_map_fd_with_map_ptr() or
> move replace_map_fd_with_map_ptr() after check_btf_info().
> The latter is probably cleaner.

Ah, that does make more sense. I can move
replace_map_fd_with_map_ptr() after check_btf_info() (or
check_attach_btf_id()) and rename it to better reflect the fact that
it's not just for maps now.

Thanks for the insights!
Hao