Re: [PATCH RFC net-next 3/5] selftests: drv-net: Test XDP head adjustment with bpf_dynptr

[Martin KaFai Lau <martin.lau@linux.dev>]

On 9/9/25 1:52 AM, Nimrod Oren wrote:
> +	if (bpf_dynptr_read(tmp_buff, hdr_len, &ptr, 0, 0) < 0)
>   		return -1;
>   
> -	if (bpf_xdp_store_bytes(ctx, 0, tmp_buff, hdr_len) < 0)
> +	if (bpf_dynptr_write(&ptr, offset, tmp_buff, hdr_len, 0) < 0)

Instead of bpf_dynptr_read() and then bpf_dynptr_write(), try to use 
bpf_dynptr_copy(). I think you have also noticed that Amery is also modifying 
xdp_native.bpf.c to test the linear access (i.e. data/data_end) with the 
bpf_xdp_pull_data addition. Not sure if xdp_native.bpf.c wants to keep testing 
both (data/data_end and dynptr). In the bpf selftests, it does want to have test 
coverage for both and have some existing selftests for that.

> +		return -1;
> +
> +	if (bpf_xdp_adjust_head(ctx, offset) < 0)
>   		return -1;
>   
>   	return 0;