net_sched: make cls_ops->change and cls_ops->delete optional

Some schedulers don't support creating, changing or deleting classes.
Make the respective callbacks optionally and consistently return
-EOPNOTSUPP for unsupported operations, instead of currently either
-EOPNOTSUPP, -ENOSYS or no error.

In case of sch_prio and sch_multiq, the removed operations additionally
checked for an invalid class. This is not necessary since the class
argument can only orginate from ->get() or in case of ->change is 0
for creation of new classes, in which case ->change() incorrectly
returned -ENOENT.

As a side-effect, this patch fixes a possible (root-only) NULL pointer
function call in sch_ingress, which didn't implement a so far mandatory
->delete() operation.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 0 insertions, 7 deletions

diff --git a/net/sched/sch_sfq.c b/net/sched/sch_sfq.c
index 8706920a6d45..cb21380c0605 100644
--- a/net/sched/sch_sfq.c
+++ b/net/sched/sch_sfq.c
@@ -496,12 +496,6 @@ nla_put_failure:
         return -1;
 }
 
-static int sfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
-                            struct nlattr **tca, unsigned long *arg)
-{
-        return -EOPNOTSUPP;
-}
-
 static unsigned long sfq_get(struct Qdisc *sch, u32 classid)
 {
         return 0;
@@ -560,7 +554,6 @@ static void sfq_walk(struct Qdisc *sch, struct qdisc_walker *arg)
 
 static const struct Qdisc_class_ops sfq_class_ops = {
         .get            =       sfq_get,
-        .change         =       sfq_change_class,
         .tcf_chain      =       sfq_find_tcf,
         .dump           =       sfq_dump_class,
         .dump_stats     =       sfq_dump_class_stats,