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From: Yonghong Song <yhs@fb.com>
To: Muhammad Falak Reyaz <falakreyaz@gmail.com>
Cc: Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>, <bpf@vger.kernel.org>,
	"open list:NETWORKING DRIVERS" <netdev@vger.kernel.org>,
	KP Singh <kpsingh@kernel.org>, Song Liu <songliubraving@fb.com>,
	Martin KaFai Lau <kafai@fb.com>,
	John Fastabend <john.fastabend@gmail.com>,
	Jesper Dangaard Brouer <hawk@kernel.org>,
	Jakub Kicinski <kuba@kernel.org>,
	"David S . Miller" <davem@davemloft.net>,
	open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] samples: bpf: xdp1: remove duplicate code to find protocol
Date: Sun, 8 Aug 2021 17:01:29 -0700	[thread overview]
Message-ID: <4c897a6a-6f5e-b990-7c36-4258a26e1752@fb.com> (raw)
In-Reply-To: <CAOmbKqkYDXvMQntk39Ud-63G3ju+Kti2A8UFNodgJ6y1+4=AeA@mail.gmail.com>



On 8/8/21 10:19 AM, Muhammad Falak Reyaz wrote:
> On Sun, Aug 8, 2021 at 10:23 PM Yonghong Song <yhs@fb.com> wrote:
>>
>>
>>
>> On 8/8/21 5:24 AM, Muhammad Falak R Wani wrote:
>>> The code to find h_vlan_encapsulated_proto is duplicated.
>>> Remove the extra block.
>>>
>>> Signed-off-by: Muhammad Falak R Wani <falakreyaz@gmail.com>
>>> ---
>>>    samples/bpf/xdp1_kern.c | 9 ---------
>>>    1 file changed, 9 deletions(-)
>>>
>>> diff --git a/samples/bpf/xdp1_kern.c b/samples/bpf/xdp1_kern.c
>>> index 34b64394ed9c..a35e064d7726 100644
>>> --- a/samples/bpf/xdp1_kern.c
>>> +++ b/samples/bpf/xdp1_kern.c
>>> @@ -57,15 +57,6 @@ int xdp_prog1(struct xdp_md *ctx)
>>>
>>>        h_proto = eth->h_proto;
>>>
>>> -     if (h_proto == htons(ETH_P_8021Q) || h_proto == htons(ETH_P_8021AD)) {
>>> -             struct vlan_hdr *vhdr;
>>> -
>>> -             vhdr = data + nh_off;
>>> -             nh_off += sizeof(struct vlan_hdr);
>>> -             if (data + nh_off > data_end)
>>> -                     return rc;
>>> -             h_proto = vhdr->h_vlan_encapsulated_proto;
>>
>> No. This is not a duplicate. The h_proto in the above line will be used
>> in the below "if" condition.
>>
>>> -     }
>>>        if (h_proto == htons(ETH_P_8021Q) || h_proto == htons(ETH_P_8021AD)) {
>>>                struct vlan_hdr *vhdr;
>>>
>>>
> Apologies :(
> I now realize, it could be double vlan encapsulated.
> Would it make sense to add an explicit comment for newbies like me ?
> I can send a patch, if it is okay.

This is not the first time people sending a patch trying to remove this
"duplicated" code. I think it is okay to send a patch with comments to 
say this is intended to handle nested vlan, so we can save everybody's 
time. Thanks.

> 
> -mfrw
> 

      reply	other threads:[~2021-08-09  0:02 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-08 12:24 Muhammad Falak R Wani
2021-08-08 16:53 ` Yonghong Song
2021-08-08 17:19   ` Muhammad Falak Reyaz
2021-08-09  0:01     ` Yonghong Song [this message]

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