cgroup: Explicitly remove core interface files

@@ -1573,8 +1573,17 @@ static void css_clear_dir(struct cgroup_
 
 	css->flags &= ~CSS_VISIBLE;
 
-	list_for_each_entry(cfts, &css->ss->cfts, node)
+	if (!css->ss) {
+		if (cgroup_on_dfl(cgrp))
+			cfts = cgroup_base_files;
+		else
+			cfts = cgroup1_base_files;
+
 		cgroup_addrm_files(css, cgrp, cfts, false);
+	} else {
+		list_for_each_entry(cfts, &css->ss->cfts, node)
+			cgroup_addrm_files(css, cgrp, cfts, false);
+	}
 }
 
 /**

@@ -1598,14 +1607,16 @@ static int css_populate_dir(struct cgrou
 		else
 			cfts = cgroup1_base_files;
 
-		return cgroup_addrm_files(&cgrp->self, cgrp, cfts, true);
-	}
-
-	list_for_each_entry(cfts, &css->ss->cfts, node) {
-		ret = cgroup_addrm_files(css, cgrp, cfts, true);
-		if (ret < 0) {
-			failed_cfts = cfts;
-			goto err;
+		ret = cgroup_addrm_files(&cgrp->self, cgrp, cfts, true);
+		if (ret < 0)
+			return ret;
+	} else {
+		list_for_each_entry(cfts, &css->ss->cfts, node) {
+			ret = cgroup_addrm_files(css, cgrp, cfts, true);
+			if (ret < 0) {
+				failed_cfts = cfts;
+				goto err;
+			}
 		}
 	}
 

@@ -5097,10 +5108,8 @@ static int cgroup_destroy_locked(struct
 	for_each_css(css, ssid, cgrp)
 		kill_css(css);
 
-	/*
-	 * Remove @cgrp directory along with the base files.  @cgrp has an
-	 * extra ref on its kn.
-	 */
+	/* clear and remove @cgrp dir, @cgrp has an extra ref on its kn */
+	css_clear_dir(&cgrp->self);
 	kernfs_remove(cgrp->kn);
 
 	if (parent && cgroup_is_threaded(cgrp))

@@ -105,6 +105,8 @@ enum {
 struct cgroup_file {
 	/* do not access any fields from outside cgroup core */
 	struct kernfs_node *kn;
+	unsigned long notified_at;
+	struct timer_list notify_timer;
 };
 
 /*

@@ -61,6 +61,8 @@
 
 #define CGROUP_FILE_NAME_MAX		(MAX_CGROUP_TYPE_NAMELEN +	\
 					 MAX_CFTYPE_NAME + 2)
+/* let's not notify more than 100 times per second */
+#define CGROUP_FILE_NOTIFY_MIN_INTV	DIV_ROUND_UP(HZ, 100)
 
 /*
  * cgroup_mutex is the master lock.  Any modification to cgroup or its

@@ -1554,6 +1556,8 @@ static void cgroup_rm_file(struct cgroup
 		spin_lock_irq(&cgroup_file_kn_lock);
 		cfile->kn = NULL;
 		spin_unlock_irq(&cgroup_file_kn_lock);
+
+		del_timer_sync(&cfile->notify_timer);
 	}
 
 	kernfs_remove_by_name(cgrp->kn, cgroup_file_name(cgrp, cft, name));

@@ -3532,6 +3536,12 @@ static int cgroup_kn_set_ugid(struct ker
 	return kernfs_setattr(kn, &iattr);
 }
 
+static void cgroup_file_notify_timer(struct timer_list *timer)
+{
+	cgroup_file_notify(container_of(timer, struct cgroup_file,
+					notify_timer));
+}
+
 static int cgroup_add_file(struct cgroup_subsys_state *css, struct cgroup *cgrp,
 			   struct cftype *cft)
 {

@@ -3558,6 +3568,8 @@ static int cgroup_add_file(struct cgroup
 	if (cft->file_offset) {
 		struct cgroup_file *cfile = (void *)css + cft->file_offset;
 
+		timer_setup(&cfile->notify_timer, cgroup_file_notify_timer, 0);
+
 		spin_lock_irq(&cgroup_file_kn_lock);
 		cfile->kn = kn;
 		spin_unlock_irq(&cgroup_file_kn_lock);

@@ -3807,8 +3819,17 @@ void cgroup_file_notify(struct cgroup_fi
 	unsigned long flags;
 
 	spin_lock_irqsave(&cgroup_file_kn_lock, flags);
-	if (cfile->kn)
-		kernfs_notify(cfile->kn);
+	if (cfile->kn) {
+		unsigned long last = cfile->notified_at;
+		unsigned long next = last + CGROUP_FILE_NOTIFY_MIN_INTV;
+
+		if (time_in_range(jiffies, last, next)) {
+			timer_reduce(&cfile->notify_timer, next);
+		} else {
+			kernfs_notify(cfile->kn);
+			cfile->notified_at = jiffies;
+		}
+	}
 	spin_unlock_irqrestore(&cgroup_file_kn_lock, flags);
 }