[LTP] [PATCH v8 2/2] tst_cgroup.c: Add a cgroup pseudo controller

[Wei Gao]

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" pseudo
controller.

Signed-off-by: Wei Gao <wegao@suse.com>
---
 lib/tst_cgroup.c | 54 +++++++++++++++++++++++++++++++-----------------
 1 file changed, 35 insertions(+), 19 deletions(-)

diff --git a/lib/tst_cgroup.c b/lib/tst_cgroup.c
index 77575431d..6a70bf4b4 100644
--- a/lib/tst_cgroup.c
+++ b/lib/tst_cgroup.c
@@ -94,9 +94,10 @@ enum cgroup_ctrl_indx {
 	CTRL_MISC,
 	CTRL_PERFEVENT,
 	CTRL_DEBUG,
-	CTRL_RDMA
+	CTRL_RDMA,
+	CTRL_PSEUDO
 };
-#define CTRLS_MAX CTRL_RDMA
+#define CTRLS_MAX CTRL_PSEUDO
 
 /* At most we can have one cgroup V1 tree for each controller and one
  * (empty) v2 tree.
@@ -259,6 +260,10 @@ static const struct cgroup_file rdma_ctrl_files[] = {
 	{ }
 };
 
+static const struct cgroup_file cgroup_pseudo_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 }
@@ -282,6 +287,7 @@ 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(cgroup_pseudo, CTRL_PSEUDO),
 	{ }
 };
 
@@ -798,6 +804,7 @@ 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 cgroup_pseudo = !strcmp(ctrl->ctrl_name, "cgroup_pseudo");
 
 	if (!ctrl) {
 		tst_brk(TBROK, "'%s' controller is unknown to LTP", ctrl_name);
@@ -827,6 +834,9 @@ void tst_cg_require(const char *const ctrl_name,
 	if (options->needs_ver != TST_CG_V2)
 		cgroup_mount_v1(ctrl);
 
+	if (cgroup_pseudo)
+		ctrl->ctrl_root = roots;
+
 	if (!ctrl->ctrl_root) {
 		tst_brk(TCONF,
 			"'%s' controller required, but not available",
@@ -849,13 +859,15 @@ mkdirs:
 			ctrl->ctrl_name);
 	}
 
-	if (cgroup_ctrl_on_v2(ctrl)) {
-		if (root->we_mounted_it) {
-			SAFE_FILE_PRINTFAT(root->mnt_dir.dir_fd,
-					   cgsc, "+%s", ctrl->ctrl_name);
-		} else {
-			tst_file_printfat(root->mnt_dir.dir_fd,
-					  cgsc, "+%s", ctrl->ctrl_name);
+	if (!cgroup_pseudo) {
+		if (cgroup_ctrl_on_v2(ctrl)) {
+			if (root->we_mounted_it) {
+				SAFE_FILE_PRINTFAT(root->mnt_dir.dir_fd,
+						cgsc, "+%s", ctrl->ctrl_name);
+			} else {
+				tst_file_printfat(root->mnt_dir.dir_fd,
+						cgsc, "+%s", ctrl->ctrl_name);
+			}
 		}
 	}
 
@@ -864,15 +876,17 @@ mkdirs:
 	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 (!cgroup_pseudo) {
+		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);
@@ -1050,8 +1064,10 @@ 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, "cgroup_pseudo")) {
+			SAFE_CG_PRINTF(parent, "cgroup.subtree_control",
+					"+%s", ctrl->ctrl_name);
+		}
 	}
 
 	for (i = 0; cg->dirs[i]; i++)
-- 
2.35.3