Re: [PATCH] samples: bpf: xdp1: remove duplicate code to find protocol

From: Yonghong Song
Date: Sun Aug 08 2021 - 20:02:00 EST




On 8/8/21 10:19 AM, Muhammad Falak Reyaz wrote:
On Sun, Aug 8, 2021 at 10:23 PM Yonghong Song <yhs@xxxxxx> 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@xxxxxxxxx>
---
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