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>

7 files changed, 6 insertions, 85 deletions

diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index bef2d645a366..166fcca86e7a 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -1417,7 +1417,9 @@ static int tc_ctl_tclass(struct sk_buff *skb, struct nlmsghdr *n, void *arg)
                                 goto out;
                         break;
                 case RTM_DELTCLASS:
-                        err = cops->delete(q, cl);
+                        err = -EOPNOTSUPP;
+                        if (cops->delete)
+                                err = cops->delete(q, cl);
                         if (err == 0)
                                 tclass_notify(skb, n, q, cl, RTM_DELTCLASS);
                         goto out;
@@ -1431,7 +1433,9 @@ static int tc_ctl_tclass(struct sk_buff *skb, struct nlmsghdr *n, void *arg)
         }
 
         new_cl = cl;
-        err = cops->change(q, clid, pid, tca, &new_cl);
+        err = -EOPNOTSUPP;
+        if (cops->change)
+                err = cops->change(q, clid, pid, tca, &new_cl);
         if (err == 0)
                 tclass_notify(skb, n, q, new_cl, RTM_NEWTCLASS);
 
diff --git a/net/sched/sch_ingress.c b/net/sched/sch_ingress.c
index ace7902b5097..a9e646bdb605 100644
--- a/net/sched/sch_ingress.c
+++ b/net/sched/sch_ingress.c
@@ -42,12 +42,6 @@ static void ingress_put(struct Qdisc *sch, unsigned long cl)
 {
 }
 
-static int ingress_change(struct Qdisc *sch, u32 classid, u32 parent,
-                          struct nlattr **tca, unsigned long *arg)
-{
-        return 0;
-}
-
 static void ingress_walk(struct Qdisc *sch, struct qdisc_walker *walker)
 {
         return;
@@ -120,7 +114,6 @@ static const struct Qdisc_class_ops ingress_class_ops = {
         .leaf           =       ingress_leaf,
         .get            =       ingress_get,
         .put            =       ingress_put,
-        .change         =       ingress_change,
         .walk           =       ingress_walk,
         .tcf_chain      =       ingress_find_tcf,
         .bind_tcf       =       ingress_bind_filter,
diff --git a/net/sched/sch_multiq.c b/net/sched/sch_multiq.c
index 912731203047..a0ffe7158ff3 100644
--- a/net/sched/sch_multiq.c
+++ b/net/sched/sch_multiq.c
@@ -348,26 +348,6 @@ static void multiq_put(struct Qdisc *q, unsigned long cl)
         return;
 }
 
-static int multiq_change(struct Qdisc *sch, u32 handle, u32 parent,
-                         struct nlattr **tca, unsigned long *arg)
-{
-        unsigned long cl = *arg;
-        struct multiq_sched_data *q = qdisc_priv(sch);
-
-        if (cl - 1 > q->bands)
-                return -ENOENT;
-        return 0;
-}
-
-static int multiq_delete(struct Qdisc *sch, unsigned long cl)
-{
-        struct multiq_sched_data *q = qdisc_priv(sch);
-        if (cl - 1 > q->bands)
-                return -ENOENT;
-        return 0;
-}
-
-
 static int multiq_dump_class(struct Qdisc *sch, unsigned long cl,
                              struct sk_buff *skb, struct tcmsg *tcm)
 {
@@ -430,8 +410,6 @@ static const struct Qdisc_class_ops multiq_class_ops = {
         .leaf           =       multiq_leaf,
         .get            =       multiq_get,
         .put            =       multiq_put,
-        .change         =       multiq_change,
-        .delete         =       multiq_delete,
         .walk           =       multiq_walk,
         .tcf_chain      =       multiq_find_tcf,
         .bind_tcf       =       multiq_bind,
diff --git a/net/sched/sch_prio.c b/net/sched/sch_prio.c
index 94cecef70145..209a4ca4b98d 100644
--- a/net/sched/sch_prio.c
+++ b/net/sched/sch_prio.c
@@ -311,25 +311,6 @@ static void prio_put(struct Qdisc *q, unsigned long cl)
         return;
 }
 
-static int prio_change(struct Qdisc *sch, u32 handle, u32 parent, struct nlattr **tca, unsigned long *arg)
-{
-        unsigned long cl = *arg;
-        struct prio_sched_data *q = qdisc_priv(sch);
-
-        if (cl - 1 > q->bands)
-                return -ENOENT;
-        return 0;
-}
-
-static int prio_delete(struct Qdisc *sch, unsigned long cl)
-{
-        struct prio_sched_data *q = qdisc_priv(sch);
-        if (cl - 1 > q->bands)
-                return -ENOENT;
-        return 0;
-}
-
-
 static int prio_dump_class(struct Qdisc *sch, unsigned long cl, struct sk_buff *skb,
                            struct tcmsg *tcm)
 {
@@ -392,8 +373,6 @@ static const struct Qdisc_class_ops prio_class_ops = {
         .leaf           =       prio_leaf,
         .get            =       prio_get,
         .put            =       prio_put,
-        .change         =       prio_change,
-        .delete         =       prio_delete,
         .walk           =       prio_walk,
         .tcf_chain      =       prio_find_tcf,
         .bind_tcf       =       prio_bind,
diff --git a/net/sched/sch_red.c b/net/sched/sch_red.c
index c27b8023f079..a2c4d1aa3cb1 100644
--- a/net/sched/sch_red.c
+++ b/net/sched/sch_red.c
@@ -308,17 +308,6 @@ static void red_put(struct Qdisc *sch, unsigned long arg)
         return;
 }
 
-static int red_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
-                            struct nlattr **tca, unsigned long *arg)
-{
-        return -ENOSYS;
-}
-
-static int red_delete(struct Qdisc *sch, unsigned long cl)
-{
-        return -ENOSYS;
-}
-
 static void red_walk(struct Qdisc *sch, struct qdisc_walker *walker)
 {
         if (!walker->stop) {
@@ -336,8 +325,6 @@ static const struct Qdisc_class_ops red_class_ops = {
         .leaf           =       red_leaf,
         .get            =       red_get,
         .put            =       red_put,
-        .change         =       red_change_class,
-        .delete         =       red_delete,
         .walk           =       red_walk,
         .dump           =       red_dump_class,
 };
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,
diff --git a/net/sched/sch_tbf.c b/net/sched/sch_tbf.c
index 28909699d24d..d904167e73b3 100644
--- a/net/sched/sch_tbf.c
+++ b/net/sched/sch_tbf.c
@@ -410,17 +410,6 @@ static void tbf_put(struct Qdisc *sch, unsigned long arg)
 {
 }
 
-static int tbf_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
-                            struct nlattr **tca, unsigned long *arg)
-{
-        return -ENOSYS;
-}
-
-static int tbf_delete(struct Qdisc *sch, unsigned long arg)
-{
-        return -ENOSYS;
-}
-
 static void tbf_walk(struct Qdisc *sch, struct qdisc_walker *walker)
 {
         if (!walker->stop) {
@@ -439,8 +428,6 @@ static const struct Qdisc_class_ops tbf_class_ops =
         .leaf           =       tbf_leaf,
         .get            =       tbf_get,
         .put            =       tbf_put,
-        .change         =       tbf_change_class,
-        .delete         =       tbf_delete,
         .walk           =       tbf_walk,
         .dump           =       tbf_dump_class,
 };