[RFC PATCH 10/19] mm/damon/sysfs: implement probe dir

[SeongJae Park <sj@kernel.org>]

Implement sysfs directory for letting users install each data probe.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/sysfs.c | 119 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 119 insertions(+)

diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
index ccd19fc062f31..fac4e37aa2851 100644
--- a/mm/damon/sysfs.c
+++ b/mm/damon/sysfs.c
@@ -747,12 +747,43 @@ static const struct kobj_type damon_sysfs_intervals_ktype = {
 	.default_groups = damon_sysfs_intervals_groups,
 };
 
+/*
+ * probe directory
+ */
+
+struct damon_sysfs_probe {
+	struct kobject kobj;
+};
+
+static struct damon_sysfs_probe *damon_sysfs_probe_alloc(void)
+{
+	return kzalloc_obj(struct damon_sysfs_probe);
+}
+
+static void damon_sysfs_probe_release(struct kobject *kobj)
+{
+	kfree(container_of(kobj, struct damon_sysfs_probe, kobj));
+}
+
+static struct attribute *damon_sysfs_probe_attrs[] = {
+	NULL,
+};
+ATTRIBUTE_GROUPS(damon_sysfs_probe);
+
+const struct kobj_type damon_sysfs_probe_ktype = {
+	.release = damon_sysfs_probe_release,
+	.sysfs_ops = &kobj_sysfs_ops,
+	.default_groups = damon_sysfs_probe_groups,
+};
+
 /*
  * probes directory
  */
 
 struct damon_sysfs_probes {
 	struct kobject kobj;
+	struct damon_sysfs_probe **probes_arr;
+	int nr;
 };
 
 static struct damon_sysfs_probes *damon_sysfs_probes_alloc(void)
@@ -760,12 +791,99 @@ static struct damon_sysfs_probes *damon_sysfs_probes_alloc(void)
 	return kzalloc_obj(struct damon_sysfs_probes);
 }
 
+static void damon_sysfs_probes_rm_dirs(
+		struct damon_sysfs_probes *probes)
+{
+	struct damon_sysfs_probe **probes_arr = probes->probes_arr;
+	int i;
+
+	for (i = 0; i < probes->nr; i++)
+		kobject_put(&probes_arr[i]->kobj);
+	probes->nr = 0;
+	kfree(probes_arr);
+	probes->probes_arr = NULL;
+}
+
+static int damon_sysfs_probes_add_dirs(
+		struct damon_sysfs_probes *probes, int nr_probes)
+{
+	struct damon_sysfs_probe **probes_arr, *probe;
+	int err, i;
+
+	damon_sysfs_probes_rm_dirs(probes);
+	if (!nr_probes)
+		return 0;
+
+	probes_arr = kmalloc_objs(*probes_arr, nr_probes,
+				   GFP_KERNEL | __GFP_NOWARN);
+	if (!probes_arr)
+		return -ENOMEM;
+	probes->probes_arr = probes_arr;
+
+	for (i = 0; i < nr_probes; i++) {
+		probe = damon_sysfs_probe_alloc();
+		if (!probe) {
+			damon_sysfs_probes_rm_dirs(probes);
+			return -ENOMEM;
+		}
+
+		err = kobject_init_and_add(&probe->kobj,
+				&damon_sysfs_probe_ktype, &probes->kobj,
+				"%d", i);
+		if (err) {
+			kobject_put(&probe->kobj);
+			damon_sysfs_probes_rm_dirs(probes);
+			return err;
+		}
+
+		probes_arr[i] = probe;
+		probes->nr++;
+	}
+	return 0;
+}
+
+static ssize_t nr_probes_show(struct kobject *kobj,
+		struct kobj_attribute *attr, char *buf)
+{
+	struct damon_sysfs_probes *probes = container_of(kobj,
+			struct damon_sysfs_probes, kobj);
+
+	return sysfs_emit(buf, "%d\n", probes->nr);
+}
+
+static ssize_t nr_probes_store(struct kobject *kobj,
+		struct kobj_attribute *attr, const char *buf, size_t count)
+{
+	struct damon_sysfs_probes *probes;
+	int nr, err = kstrtoint(buf, 0, &nr);
+
+	if (err)
+		return err;
+	if (nr < 0 || nr > DAMON_MAX_PROBES)
+		return -EINVAL;
+
+	probes = container_of(kobj, struct damon_sysfs_probes, kobj);
+
+	if (!mutex_trylock(&damon_sysfs_lock))
+		return -EBUSY;
+	err = damon_sysfs_probes_add_dirs(probes, nr);
+	mutex_unlock(&damon_sysfs_lock);
+	if (err)
+		return err;
+
+	return count;
+}
+
 static void damon_sysfs_probes_release(struct kobject *kobj)
 {
 	kfree(container_of(kobj, struct damon_sysfs_probes, kobj));
 }
 
+static struct kobj_attribute damon_sysfs_probes_nr_probes =
+		__ATTR_RW_MODE(nr_probes, 0600);
+
 static struct attribute *damon_sysfs_probes_attrs[] = {
+	&damon_sysfs_probes_nr_probes.attr,
 	NULL,
 };
 ATTRIBUTE_GROUPS(damon_sysfs_probes);
@@ -862,6 +980,7 @@ static void damon_sysfs_attrs_rm_dirs(struct damon_sysfs_attrs *attrs)
 	kobject_put(&attrs->nr_regions_range->kobj);
 	damon_sysfs_intervals_rm_dirs(attrs->intervals);
 	kobject_put(&attrs->intervals->kobj);
+	damon_sysfs_probes_rm_dirs(attrs->probes);
 	kobject_put(&attrs->probes->kobj);
 }
 
-- 
2.47.3