From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Dave Marchevsky <davemarchevsky@fb.com>
Cc: bpf <bpf@vger.kernel.org>, Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>, Yonghong Song <yhs@fb.com>,
Networking <netdev@vger.kernel.org>
Subject: Re: [PATCH v4 bpf-next 5/9] libbpf: use static const fmt string in __bpf_printk
Date: Thu, 2 Sep 2021 16:09:19 -0700 [thread overview]
Message-ID: <CAEf4Bza3Aye9fyhMvR_iuF93ES3OeFwgoXZxCbA=C_+EpLQk_w@mail.gmail.com> (raw)
In-Reply-To: <20210902171929.3922667-6-davemarchevsky@fb.com>
On Thu, Sep 2, 2021 at 10:23 AM Dave Marchevsky <davemarchevsky@fb.com> wrote:
>
> The __bpf_printk convenience macro was using a 'char' fmt string holder
> as it predates support for globals in libbpf. Move to more efficient
> 'static const char', but provide a fallback to the old way via
> BPF_NO_GLOBAL_DATA so users on old kernels can still use the macro.
>
> Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
> ---
Great, thanks!
Acked-by: Andrii Nakryiko <andrii@kernel.org>
> tools/lib/bpf/bpf_helpers.h | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h
> index a7e73be6dac4..7df7d9a23099 100644
> --- a/tools/lib/bpf/bpf_helpers.h
> +++ b/tools/lib/bpf/bpf_helpers.h
> @@ -216,10 +216,16 @@ enum libbpf_tristate {
> ___param, sizeof(___param)); \
> })
>
> +#ifdef BPF_NO_GLOBAL_DATA
> +#define BPF_PRINTK_FMT_MOD
> +#else
> +#define BPF_PRINTK_FMT_MOD static const
> +#endif
> +
> /* Helper macro to print out debug messages */
> #define __bpf_printk(fmt, ...) \
> ({ \
> - char ____fmt[] = fmt; \
> + BPF_PRINTK_FMT_MOD char ____fmt[] = fmt; \
> bpf_trace_printk(____fmt, sizeof(____fmt), \
> ##__VA_ARGS__); \
> })
> --
> 2.30.2
>
next prev parent reply other threads:[~2021-09-02 23:09 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-02 17:19 [PATCH v4 bpf-next 0/9] bpf: implement variadic printk helper Dave Marchevsky
2021-09-02 17:19 ` [PATCH v4 bpf-next 1/9] bpf: merge printk and seq_printf VARARG max macros Dave Marchevsky
2021-09-02 17:19 ` [PATCH v4 bpf-next 2/9] selftests/bpf: stop using bpf_program__load Dave Marchevsky
2021-09-02 22:58 ` Andrii Nakryiko
2021-09-02 17:19 ` [PATCH v4 bpf-next 3/9] bpf: add bpf_trace_vprintk helper Dave Marchevsky
2021-09-02 17:19 ` [PATCH v4 bpf-next 4/9] libbpf: Modify bpf_printk to choose helper based on arg count Dave Marchevsky
2021-09-02 23:08 ` Andrii Nakryiko
2021-09-02 17:19 ` [PATCH v4 bpf-next 5/9] libbpf: use static const fmt string in __bpf_printk Dave Marchevsky
2021-09-02 23:09 ` Andrii Nakryiko [this message]
2021-09-02 17:19 ` [PATCH v4 bpf-next 6/9] bpftool: only probe trace_vprintk feature in 'full' mode Dave Marchevsky
2021-09-02 23:10 ` Andrii Nakryiko
2021-09-02 17:19 ` [PATCH v4 bpf-next 7/9] selftests/bpf: Migrate prog_tests/trace_printk CHECKs to ASSERTs Dave Marchevsky
2021-09-02 17:19 ` [PATCH v4 bpf-next 8/9] selftests/bpf: add trace_vprintk test prog Dave Marchevsky
2021-09-02 23:13 ` Andrii Nakryiko
2021-09-02 17:19 ` [PATCH v4 bpf-next 9/9] selftests/bpf: Add test for bpf_printk w/ 0 fmt args Dave Marchevsky
2021-09-02 23:14 ` Andrii Nakryiko
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