[bpf-next PATCH v2 4/4] bpf: selftests, add printk to test_sk_lookup_kern to encode null ptr check

[John Fastabend <john.fastabend@xxxxxxxxx>]

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.

Acked-by: Andrii Nakryiko <andriin@xxxxxx>
Signed-off-by: John Fastabend <john.fastabend@xxxxxxxxx>
---
 .../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;