[PATCH] selftests: cgroup: fix unexpected failure on test_memcg_sock

[Haifeng Xu <haifeng.xu@shopee.com>]

Before server got a client connection, there were some memory allocation
in the test memcg, such as user stack. So do not count those memory not
related to socket when checking socket memory accounting.

Signed-off-by: Haifeng Xu <haifeng.xu@shopee.com>
---
 tools/testing/selftests/cgroup/test_memcontrol.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/cgroup/test_memcontrol.c b/tools/testing/selftests/cgroup/test_memcontrol.c
index f4f7c0aef702..9e0d6d315826 100644
--- a/tools/testing/selftests/cgroup/test_memcontrol.c
+++ b/tools/testing/selftests/cgroup/test_memcontrol.c
@@ -987,7 +987,9 @@ static int tcp_client(const char *cgroup, unsigned short port)
 	char servport[6];
 	int retries = 0x10; /* nice round number */
 	int sk, ret;
+	long allocated;
 
+	allocated = cg_read_long(cgroup, "memory.current");
 	snprintf(servport, sizeof(servport), "%hd", port);
 	ret = getaddrinfo(server, servport, NULL, &ai);
 	if (ret)
@@ -1015,7 +1017,8 @@ static int tcp_client(const char *cgroup, unsigned short port)
 		if (current < 0 || sock < 0)
 			goto close_sk;
 
-		if (values_close(current, sock, 10)) {
+		/* exclude the memory not related to socket connection */
+		if (values_close(current - allocated, sock, 10)) {
 			ret = KSFT_PASS;
 			break;
 		}
-- 
2.25.1