[PATCH 1/2] selftests: cgroup: skip test_memcg_sock under cgroup.memory=nosocket

[Konstantin Khorenko]

With cgroup.memory=nosocket the memory controller does not charge
socket memory, so the "sock " entry of memory.stat stays 0 and
memory.current moves only by the kernel objects accept() allocates.
tcp_client() then passes on 0 == 0 without having checked any
accounting, or fails if those objects took a fresh charge batch.

Look for nosocket among the cgroup.memory= options on the kernel command
line and skip the test there.

Assisted-by: LLM
Signed-off-by: Konstantin Khorenko <khorenko@xxxxxxxxxxxxx>
---
 tools/testing/selftests/cgroup/test_memcontrol.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/tools/testing/selftests/cgroup/test_memcontrol.c b/tools/testing/selftests/cgroup/test_memcontrol.c
index 0ed82347044ed..a24c1e07b2035 100644
--- a/tools/testing/selftests/cgroup/test_memcontrol.c
+++ b/tools/testing/selftests/cgroup/test_memcontrol.c
@@ -1379,6 +1379,24 @@ static int tcp_client(const char *cgroup, unsigned short port)
 	return ret;
 }
 
+static bool memcg_sockets_disabled(void)
+{
+	char buf[4 * BUF_SIZE], *opt;
+
+	if (read_text("/proc/cmdline", buf, sizeof(buf)) <= 0)
+		return false;
+
+	for (opt = strstr(buf, "cgroup.memory="); opt;
+	     opt = strstr(opt + 1, "cgroup.memory=")) {
+		char *end = strchrnul(opt, ' ');
+		char *ns = strstr(opt, "nosocket");
+
+		if (ns && ns < end)
+			return true;
+	}
+	return false;
+}
+
 /*
  * This test checks socket memory accounting.
  * The test forks a TCP server listens on a random port between 1000
@@ -1394,6 +1412,9 @@ static int test_memcg_sock(const char *root)
 	char *memcg;
 	long sock_post = -1;
 
+	if (memcg_sockets_disabled())
+		return KSFT_SKIP;
+
 	memcg = cg_name(root, "memcg_test");
 	if (!memcg)
 		goto cleanup;

-- 
2.43.0