From: Stephen Kitt <steve@sk2.org>
To: 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,
"Gustavo A . R . Silva" <gustavo@embeddedor.com>,
Stephen Kitt <steve@sk2.org>
Subject: [PATCH v2] bpf: use flexible array members, not zero-length
Date: Mon, 30 Sep 2019 09:38:59 +0200 [thread overview]
Message-ID: <20190930073858.7639-1-steve@sk2.org> (raw)
In-Reply-To: <F15E974F-4B7F-4819-B640-682A0A3A47C5@fb.com>
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
];
...
};
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..930ada2276bf 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[];
};
/* The minimum bpf_func_info checked by the loader */
--
2.20.1
next prev parent reply other threads:[~2019-09-30 7:41 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
2019-09-30 7:38 ` Stephen Kitt [this message]
2019-09-30 23:18 ` [PATCH v2] " Gustavo A. R. Silva
2019-09-30 7:41 ` [PATCH] " Stephen Kitt
2019-09-30 8:50 ` Daniel Borkmann
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