net: sched: implement action API that deletes action by index

Implement new action API function that atomically finds and deletes action
from idr by index. Intended to be used by lockless actions that do not rely
on rtnl lock.

Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/act_api.h

@@ -153,6 +153,7 @@ int tcf_idr_create(struct tc_action_net *tn, u32 index, struct nlattr *est,
 		   int bind, bool cpustats);
 void tcf_idr_insert(struct tc_action_net *tn, struct tc_action *a);
 
+int tcf_idr_delete_index(struct tc_action_net *tn, u32 index);
 int __tcf_idr_release(struct tc_action *a, bool bind, bool strict);
 
 static inline int tcf_idr_release(struct tc_action *a, bool bind)

net/sched/act_api.c

@@ -319,6 +319,45 @@ bool tcf_idr_check(struct tc_action_net *tn, u32 index, struct tc_action **a,
 }
 EXPORT_SYMBOL(tcf_idr_check);
 
+int tcf_idr_delete_index(struct tc_action_net *tn, u32 index)
+{
+	struct tcf_idrinfo *idrinfo = tn->idrinfo;
+	struct tc_action *p;
+	int ret = 0;
+
+	spin_lock(&idrinfo->lock);
+	p = idr_find(&idrinfo->action_idr, index);
+	if (!p) {
+		spin_unlock(&idrinfo->lock);
+		return -ENOENT;
+	}
+
+	if (!atomic_read(&p->tcfa_bindcnt)) {
+		if (refcount_dec_and_test(&p->tcfa_refcnt)) {
+			struct module *owner = p->ops->owner;
+
+			WARN_ON(p != idr_remove(&idrinfo->action_idr,
+						p->tcfa_index));
+			spin_unlock(&idrinfo->lock);
+
+			if (p->ops->cleanup)
+				p->ops->cleanup(p);
+
+			gen_kill_estimator(&p->tcfa_rate_est);
+			free_tcf(p);
+			module_put(owner);
+			return 0;
+		}
+		ret = 0;
+	} else {
+		ret = -EPERM;
+	}
+
+	spin_unlock(&idrinfo->lock);
+	return ret;
+}
+EXPORT_SYMBOL(tcf_idr_delete_index);
+
 int tcf_idr_create(struct tc_action_net *tn, u32 index, struct nlattr *est,
 		   struct tc_action **a, const struct tc_action_ops *ops,
 		   int bind, bool cpustats)