tst_cgroup.c: Add a cgroup base controller

For new test case such as kill01.c no need specific controller, it just
need LTP cgroup library start work, so we need add a "cgroup" base
controller.

Reviewed-by: Li Wang <[email protected]>
Reviewed-by: Petr Vorel <[email protected]>
Signed-off-by: Wei Gao <[email protected]>

Author: coolgw

lib/tst_cgroup.c

@@ -94,9 +94,10 @@ enum cgroup_ctrl_indx {
 	CTRL_MISC,
 	CTRL_PERFEVENT,
 	CTRL_DEBUG,
-	CTRL_RDMA
+	CTRL_RDMA,
+	CTRL_BASE
 };
-#define CTRLS_MAX CTRL_RDMA
+#define CTRLS_MAX CTRL_BASE
 
 /* At most we can have one cgroup V1 tree for each controller and one
  * (empty) v2 tree.
@@ -258,6 +259,10 @@ static const struct cgroup_file rdma_ctrl_files[] = {
 	{ }
 };
 
+static const struct cgroup_file base_ctrl_files[] = {
+	{ }
+};
+
 #define CTRL_NAME_MAX 31
 #define CGROUP_CTRL_MEMBER(x, y)[y] = { .ctrl_name = #x, .files = \
 	x ## _ctrl_files, .ctrl_indx = y, NULL, 0 }
@@ -281,6 +286,7 @@ static struct cgroup_ctrl controllers[] = {
 	CGROUP_CTRL_MEMBER(perf_event, CTRL_PERFEVENT),
 	CGROUP_CTRL_MEMBER(debug, CTRL_DEBUG),
 	CGROUP_CTRL_MEMBER(rdma, CTRL_RDMA),
+	CGROUP_CTRL_MEMBER(base, CTRL_BASE),
 	{ }
 };
 
@@ -797,6 +803,10 @@ void tst_cg_require(const char *const ctrl_name,
 	const char *const cgsc = "cgroup.subtree_control";
 	struct cgroup_ctrl *const ctrl = cgroup_find_ctrl(ctrl_name);
 	struct cgroup_root *root;
+	int base = !strcmp(ctrl->ctrl_name, "base");
+
+	if (base && options->needs_ver != TST_CG_V2)
+		tst_brk(TCONF, "Base control only support needs_ver TST_CG_V2!");
 
 	if (!ctrl) {
 		tst_brk(TBROK, "'%s' controller is unknown to LTP", ctrl_name);
@@ -826,6 +836,9 @@ void tst_cg_require(const char *const ctrl_name,
 	if (options->needs_ver != TST_CG_V2)
 		cgroup_mount_v1(ctrl);
 
+	if (base)
+		ctrl->ctrl_root = roots;
+
 	if (!ctrl->ctrl_root) {
 		tst_brk(TCONF,
 			"'%s' controller required, but not available",
@@ -848,7 +861,7 @@ void tst_cg_require(const char *const ctrl_name,
 			ctrl->ctrl_name);
 	}
 
-	if (cgroup_ctrl_on_v2(ctrl)) {
+	if (cgroup_ctrl_on_v2(ctrl) && !base) {
 		if (root->we_mounted_it) {
 			SAFE_FILE_PRINTFAT(root->mnt_dir.dir_fd,
 					   cgsc, "+%s", ctrl->ctrl_name);
@@ -863,15 +876,17 @@ void tst_cg_require(const char *const ctrl_name,
 	else
 		root->ltp_dir.ctrl_field |= root->mnt_dir.ctrl_field;
 
-	if (cgroup_ctrl_on_v2(ctrl)) {
-		SAFE_FILE_PRINTFAT(root->ltp_dir.dir_fd,
-				   cgsc, "+%s", ctrl->ctrl_name);
-	} else {
-		SAFE_FILE_PRINTFAT(root->ltp_dir.dir_fd,
-				   "cgroup.clone_children", "%d", 1);
+	if (!base) {
+		if (cgroup_ctrl_on_v2(ctrl)) {
+			SAFE_FILE_PRINTFAT(root->ltp_dir.dir_fd,
+					cgsc, "+%s", ctrl->ctrl_name);
+		} else {
+			SAFE_FILE_PRINTFAT(root->ltp_dir.dir_fd,
+					"cgroup.clone_children", "%d", 1);
 
-		if (ctrl->ctrl_indx == CTRL_CPUSET)
-			cgroup_copy_cpuset(root);
+			if (ctrl->ctrl_indx == CTRL_CPUSET)
+				cgroup_copy_cpuset(root);
+		}
 	}
 
 	cgroup_dir_mk(&root->ltp_dir, cgroup_ltp_drain_dir, &root->drain_dir);
@@ -996,7 +1011,8 @@ void tst_cg_cleanup(void)
 	}
 
 	for_each_ctrl(ctrl) {
-		if (!cgroup_ctrl_on_v2(ctrl) || !ctrl->ctrl_root->we_mounted_it)
+		if (!cgroup_ctrl_on_v2(ctrl) || !ctrl->ctrl_root->we_mounted_it
+			|| !strcmp(ctrl->ctrl_name, "base"))
 			continue;
 
 		SAFE_FILE_PRINTFAT(ctrl->ctrl_root->mnt_dir.dir_fd,
@@ -1049,8 +1065,10 @@ static void cgroup_group_add_dir(const struct tst_cg_group *const parent,
 		if (!parent || dir->dir_root->ver == TST_CG_V1)
 			continue;
 
-		SAFE_CG_PRINTF(parent, "cgroup.subtree_control",
-				   "+%s", ctrl->ctrl_name);
+		if (strcmp(ctrl->ctrl_name, "base")) {
+			SAFE_CG_PRINTF(parent, "cgroup.subtree_control",
+					"+%s", ctrl->ctrl_name);
+		}
 	}
 
 	for (i = 0; cg->dirs[i]; i++)