From: Eduard Zingerman <eddyz87@gmail.com>
To: Hou Tao <houtao@huaweicloud.com>, bpf@vger.kernel.org
Cc: Martin KaFai Lau <martin.lau@linux.dev>,
Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Andrii Nakryiko <andrii@kernel.org>, Song Liu <song@kernel.org>,
Hao Luo <haoluo@google.com>,
Yonghong Song <yonghong.song@linux.dev>,
Daniel Borkmann <daniel@iogearbox.net>,
KP Singh <kpsingh@kernel.org>, Jiri Olsa <jolsa@kernel.org>,
John Fastabend <john.fastabend@gmail.com>,
Kui-Feng Lee <thinker.li@gmail.com>,
houtao1@huawei.com, xukuohai@huawei.com
Subject: Re: [RESEND][PATCH bpf 1/2] bpf: Check the remaining info_cnt before repeating btf fields
Date: Wed, 11 Sep 2024 20:14:30 -0700 [thread overview]
Message-ID: <8efb866f50259206e127079686aed51f201c3810.camel@gmail.com> (raw)
In-Reply-To: <9a7d4f5ff0ea8af86a6d7a5b630c38cb7ecc2075.camel@gmail.com>
On Wed, 2024-09-11 at 20:03 -0700, Eduard Zingerman wrote:
[...]
> Please bear with me. Here is btf_repeat_fields():
>
> static int btf_repeat_fields(struct btf_field_info *info,
> u32 field_cnt, u32 repeat_cnt, u32 elem_size)
> {
> u32 i, j;
> u32 cur;
> ...
> cur = field_cnt;
> for (i = 0; i < repeat_cnt; i++) {
> ...
> for (j = 0; j < field_cnt; j++)
> info[cur++].off += (i + 1) * elem_size;
> }
> ...
> }
>
> The range for 'cur' is [field_cnt .. field_cnt * repeat_cnt].
> Meaning that at-least 'field_cnt * repeat_cnt' entries are necessary
> in the 'info' array.
Ok, I'm wrong.
The range for 'cur' is [field_cnt .. field_cnt * (repeat_cnt + 1)].
So with parameters passed maximal value of 'cur' is 'ret * nelems' indeed.
Sorry for the noise.
next prev parent reply other threads:[~2024-09-12 3:14 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-09-11 11:05 [RESEND][PATCH bpf 0/2] Check the remaining info_cnt before repeating btf fields Hou Tao
2024-09-11 11:05 ` [RESEND][PATCH bpf 1/2] bpf: " Hou Tao
2024-09-11 17:37 ` Eduard Zingerman
2024-09-12 1:20 ` Hou Tao
2024-09-12 3:03 ` Eduard Zingerman
2024-09-12 3:14 ` Eduard Zingerman [this message]
[not found] ` <CAFVMQ6Q64aFM7xCW_htrU0dpB+S+eEXYLSeUufTgg_eB5DEN4g@mail.gmail.com>
2024-09-12 19:45 ` Eduard Zingerman
2024-09-11 11:05 ` [RESEND][PATCH bpf 2/2] selftests/bpf: Add more test case for field flattening Hou Tao
2024-09-11 17:07 ` Eduard Zingerman
2024-09-12 1:05 ` Hou Tao
2024-09-12 2:31 ` Eduard Zingerman
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