[PATCH 2/3] selftests/cgroup: Add a test for the misc.mask cgroup interface

[Andrei Vagin <avagin@google.com>]

Add a selftest for the misc.mask cgroup interface. The test verifies
that the misc.mask file is present and has the correct default value,
that it is possible to write a new mask to the file, and that the mask is
inherited by sub-cgroups.

Signed-off-by: Andrei Vagin <avagin@google.com>
---
 tools/testing/selftests/cgroup/.gitignore  |   1 +
 tools/testing/selftests/cgroup/Makefile    |   2 +
 tools/testing/selftests/cgroup/config      |   1 +
 tools/testing/selftests/cgroup/test_misc.c | 118 +++++++++++++++++++++
 4 files changed, 122 insertions(+)
 create mode 100644 tools/testing/selftests/cgroup/test_misc.c

diff --git a/tools/testing/selftests/cgroup/.gitignore b/tools/testing/selftests/cgroup/.gitignore
index 952e4448bf07..3ced02a3634b 100644
--- a/tools/testing/selftests/cgroup/.gitignore
+++ b/tools/testing/selftests/cgroup/.gitignore
@@ -7,6 +7,7 @@ test_hugetlb_memcg
 test_kill
 test_kmem
 test_memcontrol
+test_misc
 test_pids
 test_zswap
 wait_inotify
diff --git a/tools/testing/selftests/cgroup/Makefile b/tools/testing/selftests/cgroup/Makefile
index e01584c2189a..6e9e92f89d8a 100644
--- a/tools/testing/selftests/cgroup/Makefile
+++ b/tools/testing/selftests/cgroup/Makefile
@@ -15,6 +15,7 @@ TEST_GEN_PROGS += test_hugetlb_memcg
 TEST_GEN_PROGS += test_kill
 TEST_GEN_PROGS += test_kmem
 TEST_GEN_PROGS += test_memcontrol
+TEST_GEN_PROGS += test_misc
 TEST_GEN_PROGS += test_pids
 TEST_GEN_PROGS += test_zswap
 
@@ -31,5 +32,6 @@ $(OUTPUT)/test_hugetlb_memcg: $(LIBCGROUP_O)
 $(OUTPUT)/test_kill: $(LIBCGROUP_O)
 $(OUTPUT)/test_kmem: $(LIBCGROUP_O)
 $(OUTPUT)/test_memcontrol: $(LIBCGROUP_O)
+$(OUTPUT)/test_misc: $(LIBCGROUP_O)
 $(OUTPUT)/test_pids: $(LIBCGROUP_O)
 $(OUTPUT)/test_zswap: $(LIBCGROUP_O)
diff --git a/tools/testing/selftests/cgroup/config b/tools/testing/selftests/cgroup/config
index 39f979690dd3..9e3d03736f5a 100644
--- a/tools/testing/selftests/cgroup/config
+++ b/tools/testing/selftests/cgroup/config
@@ -1,6 +1,7 @@
 CONFIG_CGROUPS=y
 CONFIG_CGROUP_CPUACCT=y
 CONFIG_CGROUP_FREEZER=y
+CONFIG_CGROUP_MISC=y
 CONFIG_CGROUP_SCHED=y
 CONFIG_MEMCG=y
 CONFIG_PAGE_COUNTER=y
diff --git a/tools/testing/selftests/cgroup/test_misc.c b/tools/testing/selftests/cgroup/test_misc.c
new file mode 100644
index 000000000000..50e8acb51852
--- /dev/null
+++ b/tools/testing/selftests/cgroup/test_misc.c
@@ -0,0 +1,118 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+
+#include <errno.h>
+#include <linux/limits.h>
+#include <signal.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "../kselftest.h"
+#include "cgroup_util.h"
+
+/*
+ * This test checks that misc.mask works correctly.
+ */
+static int test_misc_mask(const char *root)
+{
+	int ret = KSFT_FAIL;
+	char *cg_misc, *cg_misc_sub = NULL;
+
+	cg_misc = cg_name(root, "misc_test");
+	if (!cg_misc)
+		goto cleanup;
+
+	cg_misc_sub = cg_name(root, "misc_test/sub");
+	if (!cg_misc_sub)
+		goto cleanup;
+
+	if (cg_create(cg_misc))
+		goto cleanup;
+
+	if (cg_read_strcmp(cg_misc, "misc.mask",
+			   "AT_HWCAP\t0x00000000000000\t0x00000000000000\n"))
+		goto cleanup;
+
+	if (cg_write(cg_misc, "misc.mask", "AT_HWCAP 0xf0000000000000"))
+		goto cleanup;
+
+	if (cg_read_strcmp(cg_misc, "misc.mask",
+			   "AT_HWCAP\t0xf0000000000000\t0xf0000000000000\n"))
+		goto cleanup;
+
+	if (cg_write(cg_misc, "cgroup.subtree_control", "+misc"))
+		goto cleanup;
+
+	if (cg_create(cg_misc_sub))
+		goto cleanup;
+
+	if (cg_read_strcmp(cg_misc_sub, "misc.mask",
+			   "AT_HWCAP\t0x00000000000000\t0xf0000000000000\n"))
+		goto cleanup;
+
+	if (cg_write(cg_misc_sub, "misc.mask", "AT_HWCAP 0x01000000000000"))
+		goto cleanup;
+
+	if (cg_read_strcmp(cg_misc_sub, "misc.mask",
+			   "AT_HWCAP\t0x01000000000000\t0xf1000000000000\n"))
+		goto cleanup;
+
+	ret = KSFT_PASS;
+
+cleanup:
+	cg_enter_current(root);
+	cg_destroy(cg_misc_sub);
+	cg_destroy(cg_misc);
+	free(cg_misc);
+	free(cg_misc_sub);
+
+	return ret;
+}
+
+#define T(x) { x, #x }
+struct misc_test {
+	int (*fn)(const char *root);
+	const char *name;
+} tests[] = {
+	T(test_misc_mask),
+};
+#undef T
+
+int main(int argc, char **argv)
+{
+	char root[PATH_MAX];
+
+	ksft_print_header();
+	ksft_set_plan(ARRAY_SIZE(tests));
+	if (cg_find_unified_root(root, sizeof(root), NULL))
+		ksft_exit_skip("cgroup v2 isn't mounted\n");
+
+	/*
+	 * Check that misc controller is available:
+	 * misc is listed in cgroup.controllers
+	 */
+	if (cg_read_strstr(root, "cgroup.controllers", "misc"))
+		ksft_exit_skip("misc controller isn't available\n");
+
+	if (cg_read_strstr(root, "cgroup.subtree_control", "misc"))
+		if (cg_write(root, "cgroup.subtree_control", "+misc"))
+			ksft_exit_skip("Failed to set misc controller\n");
+
+	for (int i = 0; i < ARRAY_SIZE(tests); i++) {
+		switch (tests[i].fn(root)) {
+		case KSFT_PASS:
+			ksft_test_result_pass("%s\n", tests[i].name);
+			break;
+		case KSFT_SKIP:
+			ksft_test_result_skip("%s\n", tests[i].name);
+			break;
+		default:
+			ksft_test_result_fail("%s\n", tests[i].name);
+			break;
+		}
+	}
+
+	ksft_finished();
+}
-- 
2.52.0.223.gf5cc29aaa4-goog