netdev - Re: [bpf-next PATCH 4/4] bpf: selftests, add printk to test_sk_lookup

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Date:   Mon, 18 May 2020 22:06:32 -0700
From:   Andrii Nakryiko <andrii.nakryiko@...il.com>
To:     John Fastabend <john.fastabend@...il.com>
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>
Subject: Re: [bpf-next PATCH 4/4] bpf: selftests, add printk to
 test_sk_lookup_kern to encode null ptr check

On Mon, May 18, 2020 at 1:05 PM John Fastabend <john.fastabend@...il.com> wrote:
>
> Adding a printk to test_sk_lookup_kern created the reported failure
> where a pointer type is checked twice for NULL. Lets add it to the
> progs test test_sk_lookup_kern.c so we test the case from C all the
> way into the verifier.
>
> We already have printk's in selftests so seems OK to add another one.
>
> Signed-off-by: John Fastabend <john.fastabend@...il.com>
> ---

Yeah, I think it's fine.

Acked-by: Andrii Nakryiko <andriin@...com>

>  .../selftests/bpf/progs/test_sk_lookup_kern.c      |    1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/tools/testing/selftests/bpf/progs/test_sk_lookup_kern.c b/tools/testing/selftests/bpf/progs/test_sk_lookup_kern.c
> index d2b38fa..e83d0b4 100644
> --- a/tools/testing/selftests/bpf/progs/test_sk_lookup_kern.c
> +++ b/tools/testing/selftests/bpf/progs/test_sk_lookup_kern.c
> @@ -73,6 +73,7 @@ int bpf_sk_lookup_test0(struct __sk_buff *skb)
>
>         tuple_len = ipv4 ? sizeof(tuple->ipv4) : sizeof(tuple->ipv6);
>         sk = bpf_sk_lookup_tcp(skb, tuple, tuple_len, BPF_F_CURRENT_NETNS, 0);
> +       bpf_printk("sk=%d\n", sk ? 1 : 0);
>         if (sk)
>                 bpf_sk_release(sk);
>         return sk ? TC_ACT_OK : TC_ACT_UNSPEC;
>