Re: [PATCH ipsec-next,v2 2/3] xfrm: interface: Add unstable helpers for setting/getting XFRM metadata from TC-BPF

On 11/30/22 9:55 PM, Eyal Birger wrote:

...

...

• info->if_id = from->if_id;
  

• info->link = from->link;
  

• skb_dst_force(skb);
  

• info->dst_orig = skb_dst(skb);
  

• dst_hold((struct dst_entry *)md_dst);
  

• skb_dst_set(skb, (struct dst_entry *)md_dst);
  

• return 0;
  

+}

+__diag_pop()

+BTF_SET8_START(xfrm_ifc_kfunc_set) +BTF_ID_FLAGS(func, bpf_skb_get_xfrm_info) +BTF_ID_FLAGS(func, bpf_skb_set_xfrm_info) +BTF_SET8_END(xfrm_ifc_kfunc_set)

+static const struct btf_kfunc_id_set xfrm_interface_kfunc_set = {

• .owner = THIS_MODULE,
  

• .set   = &xfrm_ifc_kfunc_set,
  

+};

+int __init register_xfrm_interface_bpf(void) +{

• int err;
  

• xfrm_md_dst = metadata_dst_alloc_percpu(0, METADATA_XFRM,
  

•                                         GFP_KERNEL);
  

May be DEFINE_PER_CPU() instead?

Are you suggesting duplicating the dst init/cleanup logic here? Personally given that this happens once at module load, I think it's best to use the existing infrastructure, but am willing to add this here if you think it's better.

Agree, staying with the current patch is better. I somehow thought metadata_dst_alloc_percpu() was newly added in this patch also.