[PATCH] selftest: memcg: Skp memcg_sock test if address family not supported

[Waiman Long <longman@redhat.com>]

On systems where IPv6 isn't enabled or not configured to support
SOCK_STREAM, the test_memcg_sock test always fails. The purpose
of the test_memcg_sock test is to verify that memory.stat.sock and
memory.current values are close. If the socket() call fails, there is
no way we can test that. I believe it is better to just skip the test
in this case instead of reporting a test failure hinting that there
may be something wrong with the memcg code.

Fixes: 5f8f019380b8 ("selftests: cgroup/memcontrol: add basic test for socket accounting")
Signed-off-by: Waiman Long <longman@redhat.com>
---
 tools/testing/selftests/cgroup/test_memcontrol.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/cgroup/test_memcontrol.c b/tools/testing/selftests/cgroup/test_memcontrol.c
index 2fb096a2a9f9..3c13ef67fafb 100644
--- a/tools/testing/selftests/cgroup/test_memcontrol.c
+++ b/tools/testing/selftests/cgroup/test_memcontrol.c
@@ -1280,8 +1280,11 @@ static int tcp_server(const char *cgroup, void *arg)
 	saddr.sin6_port = htons(srv_args->port);
 
 	sk = socket(AF_INET6, SOCK_STREAM, 0);
-	if (sk < 0)
+	if (sk < 0) {
+		/* Pass back errno to the ctl_fd */
+		write(ctl_fd, &errno, sizeof(errno));
 		return ret;
+	}
 
 	if (setsockopt(sk, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes)) < 0)
 		goto cleanup;
@@ -1414,6 +1417,9 @@ static int test_memcg_sock(const char *root)
 
 		if (!err)
 			break;
+		if (err == EAFNOSUPPORT)
+			/* Skip if address family not supported by protocol */
+			goto skip;
 		if (err != EADDRINUSE)
 			goto cleanup;
 
@@ -1460,6 +1466,9 @@ static int test_memcg_sock(const char *root)
 	free(memcg);
 
 	return ret;
+skip:
+	ret = KSFT_SKIP;
+	goto cleanup;
 }
 
 /*
-- 
2.53.0