[RFC PATCH 07/27] mm/damon/sysfs: implement report producer directory

[SJ Park <sj@kernel.org>]

Implement a sysfs directory for each report producer.  Create and remove
the directories for reports/producers/nr_producers file writes.  It is a
placeholder for sysfs files that will be used for controlling each
report producer.

Signed-off-by: SJ Park <sj@kernel.org>
---
 mm/damon/sysfs.c | 71 +++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 70 insertions(+), 1 deletion(-)

diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
index d3a7cb170975a..7c6bc30c12125 100644
--- a/mm/damon/sysfs.c
+++ b/mm/damon/sysfs.c
@@ -2979,10 +2979,40 @@ static const struct kobj_type damon_sysfs_kdamonds_ktype = {
 	.default_groups = damon_sysfs_kdamonds_groups,
 };
 
+/* producer dir */
+
+struct damon_sysfs_producer {
+	struct kobject kobj;
+};
+
+static struct damon_sysfs_producer *damon_sysfs_producer_alloc(void)
+{
+	return kzalloc_obj(struct damon_sysfs_producer);
+}
+
+static void damon_sysfs_producer_release(struct kobject *kobj)
+{
+	struct damon_sysfs_producer *producer = container_of(kobj,
+			struct damon_sysfs_producer, kobj);
+	kfree(producer);
+}
+
+static struct attribute *damon_sysfs_producer_attrs[] = {
+	NULL,
+};
+ATTRIBUTE_GROUPS(damon_sysfs_producer);
+
+static const struct kobj_type damon_sysfs_producer_ktype = {
+	.release = damon_sysfs_producer_release,
+	.sysfs_ops = &kobj_sysfs_ops,
+	.default_groups = damon_sysfs_producer_groups,
+};
+
 /* producers dir */
 
 struct damon_sysfs_producers {
 	struct kobject kobj;
+	struct damon_sysfs_producer **producers_arr;
 	int nr;
 };
 
@@ -2994,14 +3024,53 @@ static struct damon_sysfs_producers *damon_sysfs_producers_alloc(void)
 static void damon_sysfs_producers_rm_dirs(
 		struct damon_sysfs_producers *producers)
 {
+	struct damon_sysfs_producer **producers_arr = producers->producers_arr;
+	int i;
+
+	for (i = 0; i < producers->nr; i++) {
+		kobject_del(&producers_arr[i]->kobj);
+		kobject_put(&producers_arr[i]->kobj);
+	}
 	producers->nr = 0;
+	kfree(producers_arr);
+	producers->producers_arr = NULL;
 }
 
 static int damon_sysfs_producers_add_dirs(
 		struct damon_sysfs_producers *producers, int nr_producers)
 {
+	struct damon_sysfs_producer **producers_arr, *producer;
+	int err, i;
+
 	damon_sysfs_producers_rm_dirs(producers);
-	producers->nr = nr_producers;
+	if (!nr_producers)
+		return 0;
+
+	producers_arr = kmalloc_objs(*producers_arr, nr_producers,
+			GFP_KERNEL | __GFP_NOWARN);
+	if (!producers_arr)
+		return -ENOMEM;
+	producers->producers_arr = producers_arr;
+
+	for (i = 0; i < nr_producers; i++) {
+		producer = damon_sysfs_producer_alloc();
+		if (!producer) {
+			damon_sysfs_producers_rm_dirs(producers);
+			return -ENOMEM;
+		}
+
+		err = kobject_init_and_add(&producer->kobj,
+				&damon_sysfs_producer_ktype, &producers->kobj,
+				"%d", i);
+		if (err) {
+			kobject_put(&producer->kobj);
+			damon_sysfs_producers_rm_dirs(producers);
+			return err;
+		}
+
+		producers_arr[i] = producer;
+		producers->nr++;
+	}
 	return 0;
 }
 
-- 
2.47.3