[PATCH bpf] selftests/bpf: Fix sockopt_sk selftest

[Yonghong Song <yhs@xxxxxx>]

Commit f4e4534850a9 ("net/netlink: fix NETLINK_LIST_MEMBERSHIPS length report")
fixed NETLINK_LIST_MEMBERSHIPS length report which caused
selftest sockopt_sk failure. The failure log looks like

  test_sockopt_sk:PASS:join_cgroup /sockopt_sk 0 nsec
  run_test:PASS:skel_load 0 nsec
  run_test:PASS:setsockopt_link 0 nsec
  run_test:PASS:getsockopt_link 0 nsec
  getsetsockopt:FAIL:Unexpected NETLINK_LIST_MEMBERSHIPS value unexpected Unexpected NETLINK_LIST_MEMBERSHIPS value: actual 8 != expected 4
  run_test:PASS:getsetsockopt 0 nsec
  #201     sockopt_sk:FAIL

In net/netlink/af_netlink.c, function netlink_getsockopt(), for NETLINK_LIST_MEMBERSHIPS,
nlk->ngroups equals to 36. Before Commit f4e4534850a9, the optlen is calculated as
  ALIGN(nlk->ngroups / 8, sizeof(u32)) = 4
After that commit, the optlen is
  ALIGN(BITS_TO_BYTES(nlk->ngroups), sizeof(u32)) = 8

Fix the test by setting the expected optlen to be 8.

Fixes: f4e4534850a9 ("net/netlink: fix NETLINK_LIST_MEMBERSHIPS length report")
Signed-off-by: Yonghong Song <yhs@xxxxxx>
---
 tools/testing/selftests/bpf/prog_tests/sockopt_sk.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/sockopt_sk.c b/tools/testing/selftests/bpf/prog_tests/sockopt_sk.c
index 4512dd808c33..05d0e07da394 100644
--- a/tools/testing/selftests/bpf/prog_tests/sockopt_sk.c
+++ b/tools/testing/selftests/bpf/prog_tests/sockopt_sk.c
@@ -209,7 +209,7 @@ static int getsetsockopt(void)
 			err, errno);
 		goto err;
 	}
-	ASSERT_EQ(optlen, 4, "Unexpected NETLINK_LIST_MEMBERSHIPS value");
+	ASSERT_EQ(optlen, 8, "Unexpected NETLINK_LIST_MEMBERSHIPS value");
 
 	free(big_buf);
 	close(fd);
-- 
2.34.1