mm/damon/sysfs: implement probe dir

Implement sysfs directory for letting users install each data probe.

Link: https://lore.kernel.org/20260518234119.97569-11-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 ccd19fc062f31c65c646ddd5bc784cf75d621d4a..6cef3eaa4431ea42604871a3266c346ec4d41684 100644 (file)
--- 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);
+
+static 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);
 }