net: sched: atomically check-allocate action

Implement function that atomically checks if action exists and either takes
reference to it, or allocates idr slot for action index to prevent
concurrent allocations of actions with same index. Use EBUSY error pointer
to indicate that idr slot is reserved.

Implement cleanup helper function that removes temporary error pointer from
idr. (in case of error between idr allocation and insertion of newly
created action to specified index)

Refactor all action init functions to insert new action to idr using this
API.

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>

1 files changed, 8 insertions, 3 deletions

diff --git a/net/sched/act_sample.c b/net/sched/act_sample.c
index a8582e1347db..3079e7be5bde 100644
--- a/net/sched/act_sample.c
+++ b/net/sched/act_sample.c
@@ -46,7 +46,7 @@ static int tcf_sample_init(struct net *net, struct nlattr *nla,
 	struct tc_sample *parm;
 	struct tcf_sample *s;
 	bool exists = false;
-	int ret;
+	int ret, err;
 
 	if (!nla)
 		return -EINVAL;
@@ -59,15 +59,20 @@ static int tcf_sample_init(struct net *net, struct nlattr *nla,
 
 	parm = nla_data(tb[TCA_SAMPLE_PARMS]);
 
-	exists = tcf_idr_check(tn, parm->index, a, bind);
+	err = tcf_idr_check_alloc(tn, &parm->index, a, bind);
+	if (err < 0)
+		return err;
+	exists = err;
 	if (exists && bind)
 		return 0;
 
 	if (!exists) {
 		ret = tcf_idr_create(tn, parm->index, est, a,
 				     &act_sample_ops, bind, false);
-		if (ret)
+		if (ret) {
+			tcf_idr_cleanup(tn, parm->index);
 			return ret;
+		}
 		ret = ACT_P_CREATED;
 	} else if (!ovr) {
 		tcf_idr_release(*a, bind);