mm/damon/sysfs: implement filter dir

Implement a sysfs directory for letting the users to configure each data
probe filter.

Link: https://lore.kernel.org/20260518234119.97569-13-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
index dad4985a826dba9618e0147af5b496287928c929..2dc475ea0f0f783cd751777258a5392b257f506b 100644 (file)
--- a/mm/damon/sysfs.c
+++ b/mm/damon/sysfs.c
@@ -747,12 +747,46 @@ static const struct kobj_type damon_sysfs_intervals_ktype = {
        .default_groups = damon_sysfs_intervals_groups,
 };
 
+/*
+ * filter directory
+ */
+
+struct damon_sysfs_filter {
+       struct kobject kobj;
+};
+
+static struct damon_sysfs_filter *damon_sysfs_filter_alloc(void)
+{
+       return kzalloc_obj(struct damon_sysfs_filter);
+}
+
+static void damon_sysfs_filter_release(struct kobject *kobj)
+{
+       struct damon_sysfs_filter *filter = container_of(kobj,
+                       struct damon_sysfs_filter, kobj);
+
+       kfree(filter);
+}
+
+static struct attribute *damon_sysfs_filter_attrs[] = {
+       NULL,
+};
+ATTRIBUTE_GROUPS(damon_sysfs_filter);
+
+static const struct kobj_type damon_sysfs_filter_ktype = {
+       .release = damon_sysfs_filter_release,
+       .sysfs_ops = &kobj_sysfs_ops,
+       .default_groups = damon_sysfs_filter_groups,
+};
+
 /*
  * filters directory
  */
 
 struct damon_sysfs_filters {
        struct kobject kobj;
+       struct damon_sysfs_filter **filters_arr;
+       int nr;
 };
 
 static struct damon_sysfs_filters *damon_sysfs_filters_alloc(void)
@@ -760,12 +794,98 @@ static struct damon_sysfs_filters *damon_sysfs_filters_alloc(void)
        return kzalloc_obj(struct damon_sysfs_filters);
 }
 
+static void damon_sysfs_filters_rm_dirs(struct damon_sysfs_filters *filters)
+{
+       struct damon_sysfs_filter **filters_arr = filters->filters_arr;
+       int i;
+
+       for (i = 0; i < filters->nr; i++)
+               kobject_put(&filters_arr[i]->kobj);
+       filters->nr = 0;
+       kfree(filters_arr);
+       filters->filters_arr = NULL;
+}
+
+static int damon_sysfs_filters_add_dirs(
+               struct damon_sysfs_filters *filters, int nr_filters)
+{
+       struct damon_sysfs_filter **filters_arr, *filter;
+       int err, i;
+
+       damon_sysfs_filters_rm_dirs(filters);
+       if (!nr_filters)
+               return 0;
+
+       filters_arr = kmalloc_objs(*filters_arr, nr_filters,
+                                  GFP_KERNEL | __GFP_NOWARN);
+       if (!filters_arr)
+               return -ENOMEM;
+       filters->filters_arr = filters_arr;
+
+       for (i = 0; i < nr_filters; i++) {
+               filter = damon_sysfs_filter_alloc();
+               if (!filter) {
+                       damon_sysfs_filters_rm_dirs(filters);
+                       return -ENOMEM;
+               }
+
+               err = kobject_init_and_add(&filter->kobj,
+                               &damon_sysfs_filter_ktype, &filters->kobj,
+                               "%d", i);
+               if (err) {
+                       kobject_put(&filter->kobj);
+                       damon_sysfs_filters_rm_dirs(filters);
+                       return err;
+               }
+
+               filters_arr[i] = filter;
+               filters->nr++;
+       }
+       return 0;
+}
+
+static ssize_t nr_filters_show(struct kobject *kobj,
+               struct kobj_attribute *attr, char *buf)
+{
+       struct damon_sysfs_filters *filters = container_of(kobj,
+                       struct damon_sysfs_filters, kobj);
+
+       return sysfs_emit(buf, "%d\n", filters->nr);
+}
+
+static ssize_t nr_filters_store(struct kobject *kobj,
+               struct kobj_attribute *attr, const char *buf, size_t count)
+{
+       struct damon_sysfs_filters *filters;
+       int nr, err = kstrtoint(buf, 0, &nr);
+
+       if (err)
+               return err;
+       if (nr < 0)
+               return -EINVAL;
+
+       filters = container_of(kobj, struct damon_sysfs_filters, kobj);
+
+       if (!mutex_trylock(&damon_sysfs_lock))
+               return -EBUSY;
+       err = damon_sysfs_filters_add_dirs(filters, nr);
+       mutex_unlock(&damon_sysfs_lock);
+       if (err)
+               return err;
+
+       return count;
+}
+
 static void damon_sysfs_filters_release(struct kobject *kobj)
 {
        kfree(container_of(kobj, struct damon_sysfs_filters, kobj));
 }
 
+static struct kobj_attribute damon_sysfs_filters_nr_attr =
+               __ATTR_RW_MODE(nr_filters, 0600);
+
 static struct attribute *damon_sysfs_filters_attrs[] = {
+       &damon_sysfs_filters_nr_attr.attr,
        NULL,
 };
 ATTRIBUTE_GROUPS(damon_sysfs_filters);
@@ -811,7 +931,10 @@ static int damon_sysfs_probe_add_dirs(struct damon_sysfs_probe *attr)
 
 static void damon_sysfs_probe_rm_dirs(struct damon_sysfs_probe *attr)
 {
-       kobject_put(&attr->filters->kobj);
+       if (attr->filters) {
+               damon_sysfs_filters_rm_dirs(attr->filters);
+               kobject_put(&attr->filters->kobj);
+       }
 }
 
 static void damon_sysfs_probe_release(struct kobject *kobj)