* [PATCH] bpf: use flexible array members, not zero-length
@ 2019-09-28 14:48 Stephen Kitt
2019-09-29 5:49 ` Gustavo A. R. Silva
2019-09-30 8:50 ` Daniel Borkmann
0 siblings, 2 replies; 7+ messages in thread
From: Stephen Kitt @ 2019-09-28 14:48 UTC (permalink / raw)
To: Alexei Starovoitov, Daniel Borkmann, Martin KaFai Lau, Song Liu,
Yonghong Song
Cc: linux-doc, netdev, bpf, Gustavo A . R . Silva, Stephen Kitt
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[];
};
/* The minimum bpf_func_info checked by the loader */
--
2.20.1
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH] bpf: use flexible array members, not zero-length
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 8:50 ` Daniel Borkmann
1 sibling, 1 reply; 7+ messages in thread
From: Gustavo A. R. Silva @ 2019-09-29 5:49 UTC (permalink / raw)
To: Stephen Kitt, Alexei Starovoitov, Daniel Borkmann,
Martin KaFai Lau, Song Liu, Yonghong Song
Cc: linux-doc, netdev, bpf
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 */
>
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] bpf: use flexible array members, not zero-length
2019-09-29 5:49 ` Gustavo A. R. Silva
@ 2019-09-30 6:07 ` Song Liu
2019-09-30 7:38 ` [PATCH v2] " Stephen Kitt
2019-09-30 7:41 ` [PATCH] " Stephen Kitt
0 siblings, 2 replies; 7+ messages in thread
From: Song Liu @ 2019-09-30 6:07 UTC (permalink / raw)
To: Gustavo A. R. Silva
Cc: Stephen Kitt, Alexei Starovoitov, Daniel Borkmann, Martin Lau,
Yonghong Song, linux-doc, netdev, bpf
> 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>
^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH v2] bpf: use flexible array members, not zero-length
2019-09-30 6:07 ` Song Liu
@ 2019-09-30 7:38 ` Stephen Kitt
2019-09-30 23:18 ` Gustavo A. R. Silva
2019-09-30 7:41 ` [PATCH] " Stephen Kitt
1 sibling, 1 reply; 7+ messages in thread
From: Stephen Kitt @ 2019-09-30 7:38 UTC (permalink / raw)
To: Alexei Starovoitov, Daniel Borkmann, Martin KaFai Lau, Song Liu,
Yonghong Song
Cc: linux-doc, netdev, bpf, Gustavo A . R . Silva, Stephen Kitt
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
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH] bpf: use flexible array members, not zero-length
2019-09-30 6:07 ` Song Liu
2019-09-30 7:38 ` [PATCH v2] " Stephen Kitt
@ 2019-09-30 7:41 ` Stephen Kitt
1 sibling, 0 replies; 7+ messages in thread
From: Stephen Kitt @ 2019-09-30 7:41 UTC (permalink / raw)
To: Song Liu
Cc: Gustavo A. R. Silva, Alexei Starovoitov, Daniel Borkmann,
Martin Lau, Yonghong Song, linux-doc, netdev, bpf
Le 30/09/2019 08:07, Song Liu a écrit :
>> On Sep 28, 2019, at 10:49 PM, Gustavo A. R. Silva
>> <gustavo@embeddedor.com> wrote:
>> I think you should preserve the tab here.
>
> Agreed.
Indeed (and I thought I’d checked whitespace changes!). V2 upcoming with
an improved Coccinelle script which preserves whitespace and fixes a
couple of other issues which appear in other files (attributes, and
structs defined alongside the field declaration).
> Besides this:
>
> Acked-by: Song Liu <songliubraving@fb.com>
Thanks!
Regards,
Stephen
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] bpf: use flexible array members, not zero-length
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 8:50 ` Daniel Borkmann
1 sibling, 0 replies; 7+ messages in thread
From: Daniel Borkmann @ 2019-09-30 8:50 UTC (permalink / raw)
To: Stephen Kitt
Cc: Alexei Starovoitov, Martin KaFai Lau, Song Liu, Yonghong Song,
linux-doc, netdev, bpf, Gustavo A . R . Silva
On Sat, Sep 28, 2019 at 04:48:14PM +0200, 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[];
> ...
> };
You did not explain the "why is it needed" part, only what your
change is doing. What [compilation?] issue are you seeing that
you're trying to fix? This sort of information must be present
in a changelog.
> Signed-off-by: Stephen Kitt <steve@sk2.org>
Thanks,
Daniel
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2] bpf: use flexible array members, not zero-length
2019-09-30 7:38 ` [PATCH v2] " Stephen Kitt
@ 2019-09-30 23:18 ` Gustavo A. R. Silva
0 siblings, 0 replies; 7+ messages in thread
From: Gustavo A. R. Silva @ 2019-09-30 23:18 UTC (permalink / raw)
To: Stephen Kitt, Alexei Starovoitov, Daniel Borkmann,
Martin KaFai Lau, Song Liu, Yonghong Song
Cc: linux-doc, netdev, bpf, Linux Kernel Mailing List
On 9/30/19 02:38, 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
> ];
> ...
> };
>
> Signed-off-by: Stephen Kitt <steve@sk2.org>
> ---
What changed in v2?
You should include a changelog here.
I encourage you to read the following document:
https://kernelnewbies.org/Outreachyfirstpatch
In particular this section "Versioning one patch revision"
Also, always CC the lkml: linux-kernel@vger.kernel.org
Thanks
--
Gustavo
> 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 */
>
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2019-09-30 16:41 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
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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 ` [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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