net/sched: act_api: skip idr replace on bound actions

tcf_idr_insert_many will replace the allocated -EBUSY pointer in
tcf_idr_check_alloc with the real action pointer, exposing it
to all operations. This operation is only needed when the action pointer
is created (ACT_P_CREATED). For actions which are bound to (returned 0),
the pointer already resides in the idr making such operation a nop.

Even though it's a nop, it's still not a cheap operation as internally
the idr code walks the idr and then does a replace on the appropriate slot.
So if the action was bound, better skip the idr replace entirely.

Signed-off-by: Pedro Tammela <[email protected]>
Acked-by: Jamal Hadi Salim <[email protected]>
Reviewed-by: Vlad Buslov <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

include/net/act_api.h

@@ -191,7 +191,7 @@ int tcf_idr_create_from_flags(struct tc_action_net *tn, u32 index,
 			      struct nlattr *est, struct tc_action **a,
 			      const struct tc_action_ops *ops, int bind,
 			      u32 flags);
-void tcf_idr_insert_many(struct tc_action *actions[]);
+void tcf_idr_insert_many(struct tc_action *actions[], int init_res[]);
 void tcf_idr_cleanup(struct tc_action_net *tn, u32 index);
 int tcf_idr_check_alloc(struct tc_action_net *tn, u32 *index,
 			struct tc_action **a, int bind);

net/sched/act_api.c

@@ -1304,19 +1304,20 @@ static const struct nla_policy tcf_action_policy[TCA_ACT_MAX + 1] = {
 	[TCA_ACT_HW_STATS]	= NLA_POLICY_BITFIELD32(TCA_ACT_HW_STATS_ANY),
 };
 
-void tcf_idr_insert_many(struct tc_action *actions[])
+void tcf_idr_insert_many(struct tc_action *actions[], int init_res[])
 {
 	struct tc_action *a;
 	int i;
 
 	tcf_act_for_each_action(i, a, actions) {
 		struct tcf_idrinfo *idrinfo;
 
+		if (init_res[i] == 0) /* Bound */
+			continue;
+
 		idrinfo = a->idrinfo;
 		mutex_lock(&idrinfo->lock);
-		/* Replace ERR_PTR(-EBUSY) allocated by tcf_idr_check_alloc if
-		 * it is just created, otherwise this is just a nop.
-		 */
+		/* Replace ERR_PTR(-EBUSY) allocated by tcf_idr_check_alloc */
 		idr_replace(&idrinfo->action_idr, a, a->tcfa_index);
 		mutex_unlock(&idrinfo->lock);
 	}
@@ -1516,7 +1517,7 @@ int tcf_action_init(struct net *net, struct tcf_proto *tp, struct nlattr *nla,
 	/* We have to commit them all together, because if any error happened in
 	 * between, we could not handle the failure gracefully.
 	 */
-	tcf_idr_insert_many(actions);
+	tcf_idr_insert_many(actions, init_res);
 
 	*attr_size = tcf_action_full_attrs_size(sz);
 	err = i - 1;

net/sched/cls_api.c

@@ -3313,7 +3313,7 @@ int tcf_exts_validate_ex(struct net *net, struct tcf_proto *tp, struct nlattr **
 			act->type = exts->type = TCA_OLD_COMPAT;
 			exts->actions[0] = act;
 			exts->nr_actions = 1;
-			tcf_idr_insert_many(exts->actions);
+			tcf_idr_insert_many(exts->actions, init_res);
 		} else if (exts->action && tb[exts->action]) {
 			int err;