From: Song Liu <songliubraving@fb.com>
To: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Cc: Stephen Kitt <steve@sk2.org>, Alexei Starovoitov <ast@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
Martin Lau <kafai@fb.com>, Yonghong Song <yhs@fb.com>,
"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"bpf@vger.kernel.org" <bpf@vger.kernel.org>
Subject: Re: [PATCH] bpf: use flexible array members, not zero-length
Date: Mon, 30 Sep 2019 06:07:47 +0000 [thread overview]
Message-ID: <F15E974F-4B7F-4819-B640-682A0A3A47C5@fb.com> (raw)
In-Reply-To: <02a551bc-7551-7c0e-0215-5ac8856b0512@embeddedor.com>
> On Sep 28, 2019, at 10:49 PM, Gustavo A. R. Silva <gustavo@embeddedor.com> wrote:
>
>
>
> 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.
Agreed.
Besides this:
Acked-by: Song Liu <songliubraving@fb.com>
next prev parent reply other threads:[~2019-09-30 6:08 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
2019-09-30 6:07 ` Song Liu [this message]
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=F15E974F-4B7F-4819-B640-682A0A3A47C5@fb.com \
--to=songliubraving@fb.com \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=gustavo@embeddedor.com \
--cc=kafai@fb.com \
--cc=linux-doc@vger.kernel.org \
--cc=netdev@vger.kernel.org \
--cc=steve@sk2.org \
--cc=yhs@fb.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).