From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
To: Stephen Kitt <steve@sk2.org>, Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
Yonghong Song <yhs@fb.com>
Cc: linux-doc@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org
Subject: Re: [PATCH] bpf: use flexible array members, not zero-length
Date: Sun, 29 Sep 2019 00:49:59 -0500 [thread overview]
Message-ID: <02a551bc-7551-7c0e-0215-5ac8856b0512@embeddedor.com> (raw)
In-Reply-To: <20190928144814.27002-1-steve@sk2.org>
On 9/28/19 09:48, Stephen Kitt wrote:
> This switches zero-length arrays in variable-length structs to C99
> flexible array members. GCC will then ensure that the arrays are
> always the last element in the struct.
>
> Coccinelle:
> @@
> identifier S, fld;
> type T;
> @@
>
> struct S {
> ...
> - T fld[0];
> + T fld[];
> ...
> };
>
> Signed-off-by: Stephen Kitt <steve@sk2.org>
> ---
> Documentation/bpf/btf.rst | 2 +-
> tools/lib/bpf/libbpf.c | 2 +-
> tools/lib/bpf/libbpf_internal.h | 2 +-
> 3 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/bpf/btf.rst b/Documentation/bpf/btf.rst
> index 4d565d202ce3..24ce50fc1fc1 100644
> --- a/Documentation/bpf/btf.rst
> +++ b/Documentation/bpf/btf.rst
> @@ -670,7 +670,7 @@ func_info for each specific ELF section.::
> __u32 sec_name_off; /* offset to section name */
> __u32 num_info;
> /* Followed by num_info * record_size number of bytes */
> - __u8 data[0];
> + __u8 data[];
> };
>
> Here, num_info must be greater than 0.
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index e0276520171b..c02ea0e1a588 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -5577,7 +5577,7 @@ static struct perf_buffer *__perf_buffer__new(int map_fd, size_t page_cnt,
> struct perf_sample_raw {
> struct perf_event_header header;
> uint32_t size;
> - char data[0];
> + char data[];
> };
>
> struct perf_sample_lost {
> diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
> index 2e83a34f8c79..26eaa3f594aa 100644
> --- a/tools/lib/bpf/libbpf_internal.h
> +++ b/tools/lib/bpf/libbpf_internal.h
> @@ -86,7 +86,7 @@ struct btf_ext_info_sec {
> __u32 sec_name_off;
> __u32 num_info;
> /* Followed by num_info * record_size number of bytes */
> - __u8 data[0];
> + __u8 data[];
I think you should preserve the tab here.
--
Gustavo
> };
>
> /* The minimum bpf_func_info checked by the loader */
>
next prev parent reply other threads:[~2019-09-28 23:12 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-28 14:48 [PATCH] bpf: use flexible array members, not zero-length Stephen Kitt
2019-09-29 5:49 ` Gustavo A. R. Silva [this message]
2019-09-30 6:07 ` Song Liu
2019-09-30 7:38 ` [PATCH v2] " Stephen Kitt
2019-09-30 23:18 ` Gustavo A. R. Silva
2019-09-30 7:41 ` [PATCH] " Stephen Kitt
2019-09-30 8:50 ` Daniel Borkmann
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