From: Xu Kuohai <xukuohai@huawei.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Xu Kuohai <xukuohai@huaweicloud.com>
Cc: bpf <bpf@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
John Fastabend <john.fastabend@gmail.com>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <martin.lau@linux.dev>,
Song Liu <song@kernel.org>, Yonghong Song <yhs@fb.com>,
KP Singh <kpsingh@kernel.org>,
Stanislav Fomichev <sdf@google.com>, Hao Luo <haoluo@google.com>,
Jiri Olsa <jolsa@kernel.org>,
"David S . Miller" <davem@davemloft.net>
Subject: Re: [PATCH bpf-next] bpf: Fix a typo in comment for DFS algorithm
Date: Wed, 26 Oct 2022 20:04:59 +0800 [thread overview]
Message-ID: <de950ed1-9ec8-e5e7-146a-91fc78b49c58@huawei.com> (raw)
In-Reply-To: <CAADnVQ+Pe73yjys+fjW1TBPscCmv6K9ur5bDPr2056ejwBBdZg@mail.gmail.com>
On 10/26/2022 2:32 PM, Alexei Starovoitov wrote:
> On Tue, Oct 25, 2022 at 7:42 PM Xu Kuohai <xukuohai@huaweicloud.com> wrote:
>>
>> From: Xu Kuohai <xukuohai@huawei.com>
>>
>> There is a typo in comment for DFS algorithm in bpf/verifier.c. The top
>> element should not be popped until all its neighbors have been checked.
>> Fix it.
>>
>> Fixes: 475fb78fbf48 ("bpf: verifier (add branch/goto checks)")
>> Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
>> ---
>> kernel/bpf/verifier.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
>> index b83a8d420520..96ba5ea6d1a6 100644
>> --- a/kernel/bpf/verifier.c
>> +++ b/kernel/bpf/verifier.c
>> @@ -10662,7 +10662,7 @@ static int check_return_code(struct bpf_verifier_env *env)
>> * 3 let S be a stack
>> * 4 S.push(v)
>> * 5 while S is not empty
>> - * 6 t <- S.pop()
>> + * 6 t <- S.top()
>
> Even with this fix the comment is not quite accurate.
> I wonder whether we should keep it or delete it completely.
The comment describes the non-recursive DFS algorithm used by the C code.
Although it does not describe the full details, it helps us to understand
the code, so I think it should be kept.
> At least please use 'peek' instead of 'top'.
OK.
prev parent reply other threads:[~2022-10-26 12:05 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-26 2:59 [PATCH bpf-next] bpf: Fix a typo in comment for DFS algorithm Xu Kuohai
2022-10-26 6:32 ` Alexei Starovoitov
2022-10-26 7:52 ` Bagas Sanjaya
2022-10-26 12:06 ` Xu Kuohai
2022-10-26 12:04 ` Xu Kuohai [this message]
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