Implement a directory for letting users to install data probe filters.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/sysfs.c | 65 +++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 64 insertions(+), 1 deletion(-)

diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
index fac4e37aa2851..250208d3de21b 100644
--- a/mm/damon/sysfs.c
+++ b/mm/damon/sysfs.c
@@ -747,12 +747,42 @@ static const struct kobj_type damon_sysfs_intervals_ktype = {
 	.default_groups = damon_sysfs_intervals_groups,
 };
 
+/*
+ * filters directory
+ */
+
+struct damon_sysfs_filters {
+	struct kobject kobj;
+};
+
+static struct damon_sysfs_filters *damon_sysfs_filters_alloc(void)
+{
+	return kzalloc_obj(struct damon_sysfs_filters);
+}
+
+static void damon_sysfs_filters_release(struct kobject *kobj)
+{
+	kfree(container_of(kobj, struct damon_sysfs_filters, kobj));
+}
+
+static struct attribute *damon_sysfs_filters_attrs[] = {
+	NULL,
+};
+ATTRIBUTE_GROUPS(damon_sysfs_filters);
+
+static const struct kobj_type damon_sysfs_filters_ktype = {
+	.release = damon_sysfs_filters_release,
+	.sysfs_ops = &kobj_sysfs_ops,
+	.default_groups = damon_sysfs_filters_groups,
+};
+
 /*
  * probe directory
  */
 
 struct damon_sysfs_probe {
 	struct kobject kobj;
+	struct damon_sysfs_filters *filters;
 };
 
 static struct damon_sysfs_probe *damon_sysfs_probe_alloc(void)
@@ -760,6 +790,30 @@ static struct damon_sysfs_probe *damon_sysfs_probe_alloc(void)
 	return kzalloc_obj(struct damon_sysfs_probe);
 }
 
+static int damon_sysfs_probe_add_dirs(struct damon_sysfs_probe *attr)
+{
+	struct damon_sysfs_filters *filters;
+	int err;
+
+	filters = damon_sysfs_filters_alloc();
+	if (!filters)
+		return -ENOMEM;
+	attr->filters = filters;
+
+	err = kobject_init_and_add(&filters->kobj, &damon_sysfs_filters_ktype,
+			&attr->kobj, "filters");
+	if (err) {
+		kobject_put(&filters->kobj);
+		attr->filters = NULL;
+	}
+	return err;
+}
+
+static void damon_sysfs_probe_rm_dirs(struct damon_sysfs_probe *attr)
+{
+	kobject_put(&attr->filters->kobj);
+}
+
 static void damon_sysfs_probe_release(struct kobject *kobj)
 {
 	kfree(container_of(kobj, struct damon_sysfs_probe, kobj));
@@ -797,8 +851,10 @@ static void damon_sysfs_probes_rm_dirs(
 	struct damon_sysfs_probe **probes_arr = probes->probes_arr;
 	int i;
 
-	for (i = 0; i < probes->nr; i++)
+	for (i = 0; i < probes->nr; i++) {
+		damon_sysfs_probe_rm_dirs(probes_arr[i]);
 		kobject_put(&probes_arr[i]->kobj);
+	}
 	probes->nr = 0;
 	kfree(probes_arr);
 	probes->probes_arr = NULL;
@@ -836,6 +892,13 @@ static int damon_sysfs_probes_add_dirs(
 			return err;
 		}
 
+		err = damon_sysfs_probe_add_dirs(probe);
+		if (err) {
+			kobject_put(&probe->kobj);
+			damon_sysfs_probes_rm_dirs(probes);
+			return err;
+		}
+
 		probes_arr[i] = probe;
 		probes->nr++;
 	}
-- 
2.47.3