net_sched: make cls_ops->tcf_chain() optional
Some qdiscs don't support attaching filters. Handle this centrally in
cls_api and return a proper errno code (EOPNOTSUPP) instead of EINVAL.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index 09cdcdf..bcfbdb4 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -181,6 +181,9 @@
if ((cops = q->ops->cl_ops) == NULL)
return -EINVAL;
+ if (cops->tcf_chain == NULL)
+ return -EOPNOTSUPP;
+
/* Do we search for filter, attached to class? */
if (TC_H_MIN(parent)) {
cl = cops->get(q, parent);
@@ -433,6 +436,8 @@
goto out;
if ((cops = q->ops->cl_ops) == NULL)
goto errout;
+ if (cops->tcf_chain == NULL)
+ goto errout;
if (TC_H_MIN(tcm->tcm_parent)) {
cl = cops->get(q, tcm->tcm_parent);
if (cl == 0)
