Re: [PATCH bpf-next 02/10] bpf: Implement BPF link handling for tc BPF programs

[Martin KaFai Lau <martin.lau@xxxxxxxxx>]

On 10/4/22 4:11 PM, Daniel Borkmann wrote:
>   static int __xtc_prog_detach(struct net_device *dev, bool ingress, u32 limit,
> -			     u32 prio)
> +			     u32 id, u32 prio)
>   {
>   	struct bpf_prog_array_item *item, *tmp;
>   	struct bpf_prog *oprog, *fprog = NULL;
> @@ -126,8 +133,11 @@ static int __xtc_prog_detach(struct net_device *dev, bool ingress, u32 limit,
>   		if (item->bpf_priority != prio) {
>   			tmp->prog = oprog;
>   			tmp->bpf_priority = item->bpf_priority;
> +			tmp->bpf_id = item->bpf_id;
>   			j++;
>   		} else {
> +			if (item->bpf_id != id)
> +				return -EBUSY;

A nit.  Should this be -ENOENT?  I think the cgroup detach is also returning 
-ENOENT for the not found case.

btw, this case should only happen from the BPF_PROG_DETACH but not the 
BPF_LINK_DETACH?