Re: [PATCH bpf-next v4 4/4] selftests/bpf: convert test_skb_cgroup_id_user to test_progs

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

On 8/13/24 5:45 AM, Alexis Lothoré (eBPF Foundation) wrote:

> +#define DST_ADDR "ff02::1"

[ ... ]

> +static int wait_local_ip(void)
> +{
> +	char *ping_cmd = ping_command(AF_INET6);
> +	int i, err;
> +
> +	for (i = 0; i < WAIT_AUTO_IP_MAX_ATTEMPT; i++) {
> +		err = SYS_NOFAIL("%s -c 1 -W 1 %s%%%s", ping_cmd, DST_ADDR,
> +				 VETH_1);

I tried in my qemu. This loop takes at least 3-4 iteration to get the ping 
through. This test could become flaky if the CI is busy.

I have been always wondering why some of the (non) test_progs has this practice.
I traced a little. I think it has something to do with the "ff02::1" used in the 
test and/or the local link address is not ready. I have not further nailed it 
down but I think it is close enough.

It will be easier to use a nodad configured v6 addr.

I take this chance to use an easier "::1" address for the test here instead of 
ff02::1. This also removed the need to add veth pair and no need to ping first.

Applied with the "::1" changes mentioned above.

Thanks for migrating the tests to test_progs. This is long overdue.




> +		if (!err)
> +			break;
> +	}
> +
> +	return err;
> +}
> +