[PATCH 10/14] net: sched: extend act API for lockless actions

[Vlad Buslov]

Implement new action API function to atomically delete action with
specified index and to atomically insert unique action. These functions are
required to implement init and delete functions for specific actions that
do not rely on rtnl lock.

Signed-off-by: Vlad Buslov <vladbu@xxxxxxxxxxxx>
---
 include/net/act_api.h |  2 ++
 net/sched/act_api.c   | 45 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 47 insertions(+)

diff --git a/include/net/act_api.h b/include/net/act_api.h
index a8c8570..bce0cf1 100644
--- a/include/net/act_api.h
+++ b/include/net/act_api.h
@@ -153,7 +153,9 @@ 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);
 void tcf_idr_insert(struct tc_action_net *tn, struct tc_action *a);
+void tcf_idr_insert_unique(struct tc_action_net *tn, struct tc_action *a);
 
+int tcf_idr_find_delete(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)
diff --git a/net/sched/act_api.c b/net/sched/act_api.c
index 2772276e..a5193dc 100644
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -330,6 +330,41 @@ bool tcf_idr_check(struct tc_action_net *tn, u32 index, struct tc_action **a,
 }
 EXPORT_SYMBOL(tcf_idr_check);
 
+int tcf_idr_find_delete(struct tc_action_net *tn, u32 index)
+{
+	struct tcf_idrinfo *idrinfo = tn->idrinfo;
+	struct tc_action *p;
+	int ret = 0;
+
+	spin_lock_bh(&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_bh(&idrinfo->lock);
+
+			tcf_action_cleanup(p);
+			module_put(owner);
+			return 0;
+		}
+		ret = 0;
+	} else {
+		ret = -EPERM;
+	}
+
+	spin_unlock_bh(&idrinfo->lock);
+	return ret;
+}
+EXPORT_SYMBOL(tcf_idr_find_delete);
+
 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)
@@ -407,6 +442,16 @@ void tcf_idr_insert(struct tc_action_net *tn, struct tc_action *a)
 }
 EXPORT_SYMBOL(tcf_idr_insert);
 
+void tcf_idr_insert_unique(struct tc_action_net *tn, struct tc_action *a)
+{
+	struct tcf_idrinfo *idrinfo = tn->idrinfo;
+
+	spin_lock_bh(&idrinfo->lock);
+	WARN_ON(idr_replace(&idrinfo->action_idr, a, a->tcfa_index));
+	spin_unlock_bh(&idrinfo->lock);
+}
+EXPORT_SYMBOL(tcf_idr_insert_unique);
+
 void tcf_idrinfo_destroy(const struct tc_action_ops *ops,
 			 struct tcf_idrinfo *idrinfo)
 {
-- 
2.7.5