[RFC PATCH v2.2 09/17] mm/damon/sysfs: implement preps directory

Implement a sysfs directory named 'preps' under the probe directory.  It
will be evolved to be used for specifying probe preps.

Signed-off-by: SJ Park <[email protected]>
---
 mm/damon/sysfs.c | 65 +++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 59 insertions(+), 6 deletions(-)

diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
index 50ff1c172d746..66a3e7de869a8 100644
--- a/mm/damon/sysfs.c
+++ b/mm/damon/sysfs.c
@@ -750,6 +750,35 @@ static const struct kobj_type damon_sysfs_intervals_ktype = {
 	.default_groups = damon_sysfs_intervals_groups,
 };
 
+/*
+ * preps directory
+ */
+
+struct damon_sysfs_preps {
+	struct kobject kobj;
+};
+
+static struct damon_sysfs_preps *damon_sysfs_preps_alloc(void)
+{
+	return kzalloc_obj(struct damon_sysfs_preps);
+}
+
+static void damon_sysfs_preps_release(struct kobject *kobj)
+{
+	kfree(container_of(kobj, struct damon_sysfs_preps, kobj));
+}
+
+static struct attribute *damon_sysfs_preps_attrs[] = {
+	NULL,
+};
+ATTRIBUTE_GROUPS(damon_sysfs_preps);
+
+static const struct kobj_type damon_sysfs_preps_ktype = {
+	.release = damon_sysfs_preps_release,
+	.sysfs_ops = &kobj_sysfs_ops,
+	.default_groups = damon_sysfs_preps_groups,
+};
+
 /*
  * filter directory
  */
@@ -1070,6 +1099,7 @@ static const struct kobj_type damon_sysfs_filters_ktype = {
 struct damon_sysfs_probe {
 	struct kobject kobj;
 	unsigned int weight;
+	struct damon_sysfs_preps *preps;
 	struct damon_sysfs_filters *filters;
 };
 
@@ -1080,25 +1110,48 @@ static struct damon_sysfs_probe *damon_sysfs_probe_alloc(void)
 
 static int damon_sysfs_probe_add_dirs(struct damon_sysfs_probe *probe)
 {
+	struct damon_sysfs_preps *preps;
 	struct damon_sysfs_filters *filters;
 	int err;
 
-	filters = damon_sysfs_filters_alloc();
-	if (!filters)
+	preps = damon_sysfs_preps_alloc();
+	if (!preps)
 		return -ENOMEM;
+	probe->preps = preps;
+
+	err = kobject_init_and_add(&preps->kobj, &damon_sysfs_preps_ktype,
+			&probe->kobj, "preps");
+	if (err)
+		goto put_preps_out;
+
+	filters = damon_sysfs_filters_alloc();
+	if (!filters) {
+		err = -ENOMEM;
+		goto del_preps_out;
+	}
 	probe->filters = filters;
 
 	err = kobject_init_and_add(&filters->kobj, &damon_sysfs_filters_ktype,
 			&probe->kobj, "filters");
-	if (err) {
-		kobject_put(&filters->kobj);
-		probe->filters = NULL;
-	}
+	if (err)
+		goto put_filters_out;
+	return err;
+
+put_filters_out:
+	kobject_put(&filters->kobj);
+	probe->filters = NULL;
+del_preps_out:
+	kobject_del(&preps->kobj);
+put_preps_out:
+	kobject_put(&preps->kobj);
+	probe->preps = NULL;
 	return err;
 }
 
 static void damon_sysfs_probe_rm_dirs(struct damon_sysfs_probe *probe)
 {
+	if (probe->preps)
+		kobject_put(&probe->preps->kobj);
 	if (probe->filters) {
 		damon_sysfs_filters_rm_dirs(probe->filters);
 		kobject_put(&probe->filters->kobj);
-- 
2.47.3