[RFC PATCH v2.1 12/17] mm/damon/sysfs: implement prep_action file

[SJ Park <sj@kernel.org>]

Add a file named prep_action under the prep directory.  It represents
the corresponding probe preparation action.

Signed-off-by: SJ Park <sj@kernel.org>
---
 mm/damon/sysfs.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 57 insertions(+)

diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
index 2ec33280a7a83..0173f37fdbf3d 100644
--- a/mm/damon/sysfs.c
+++ b/mm/damon/sysfs.c
@@ -756,6 +756,7 @@ static const struct kobj_type damon_sysfs_intervals_ktype = {
 
 struct damon_sysfs_prep {
 	struct kobject kobj;
+	enum damon_prep_action action;
 };
 
 static struct damon_sysfs_prep *damon_sysfs_prep_alloc(void)
@@ -765,9 +766,61 @@ static struct damon_sysfs_prep *damon_sysfs_prep_alloc(void)
 	prep = kzalloc_obj(struct damon_sysfs_prep);
 	if (!prep)
 		return prep;
+	prep->action = DAMON_PREP_SET_PGIDLE;
 	return prep;
 }
 
+struct damon_sysfs_prep_action_name {
+	const enum damon_prep_action action;
+	const char *name;
+};
+
+static const struct damon_sysfs_prep_action_name
+damon_sysfs_prep_action_names[] = {
+	{
+		.action = DAMON_PREP_SET_PGIDLE,
+		.name = "set_pgidle",
+	},
+};
+
+static ssize_t prep_action_show(struct kobject *kobj,
+		struct kobj_attribute *attr, char *buf)
+{
+	struct damon_sysfs_prep *prep = container_of(kobj,
+			struct damon_sysfs_prep, kobj);
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(damon_sysfs_prep_action_names); i++) {
+		const struct damon_sysfs_prep_action_name *action_name;
+
+		action_name = &damon_sysfs_prep_action_names[i];
+		if (action_name->action == prep->action)
+			return sysfs_emit(buf, "%s\n", action_name->name);
+	}
+	return -EINVAL;
+}
+
+static ssize_t prep_action_store(struct kobject *kobj,
+		struct kobj_attribute *attr, const char *buf, size_t count)
+{
+	struct damon_sysfs_prep *prep = container_of(kobj,
+			struct damon_sysfs_prep, kobj);
+	ssize_t ret = -EINVAL;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(damon_sysfs_prep_action_names); i++) {
+		const struct damon_sysfs_prep_action_name *action_name;
+
+		action_name = &damon_sysfs_prep_action_names[i];
+		if (sysfs_streq(buf, action_name->name)) {
+			prep->action = action_name->action;
+			ret = count;
+			break;
+		}
+	}
+	return ret;
+}
+
 static void damon_sysfs_prep_release(struct kobject *kobj)
 {
 	struct damon_sysfs_prep *prep = container_of(kobj,
@@ -776,7 +829,11 @@ static void damon_sysfs_prep_release(struct kobject *kobj)
 	kfree(prep);
 }
 
+static struct kobj_attribute damon_sysfs_prep_prep_action_attr =
+		__ATTR_RW_MODE(prep_action, 0600);
+
 static struct attribute *damon_sysfs_prep_attrs[] = {
+	&damon_sysfs_prep_prep_action_attr.attr,
 	NULL,
 };
 ATTRIBUTE_GROUPS(damon_sysfs_prep);
-- 
2.47.3