net: sched: add an offload graft helper

Qdisc graft operation of offload-capable qdiscs performs a few
extra steps which are identical among all the qdiscs.  Add
a helper to share this code.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: John Hurley <john.hurley@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/sch_generic.h

@@ -582,6 +582,10 @@ void qdisc_tree_reduce_backlog(struct Qdisc *qdisc, unsigned int n,
 #ifdef CONFIG_NET_SCHED
 int qdisc_offload_dump_helper(struct Qdisc *q, enum tc_setup_type type,
 			      void *type_data);
+void qdisc_offload_graft_helper(struct net_device *dev, struct Qdisc *sch,
+				struct Qdisc *new, struct Qdisc *old,
+				enum tc_setup_type type, void *type_data,
+				struct netlink_ext_ack *extack);
 #else
 static inline int
 qdisc_offload_dump_helper(struct Qdisc *q, enum tc_setup_type type,
@@ -590,6 +594,14 @@ qdisc_offload_dump_helper(struct Qdisc *q, enum tc_setup_type type,
 	q->flags &= ~TCQ_F_OFFLOADED;
 	return 0;
 }
+
+static inline void
+qdisc_offload_graft_helper(struct net_device *dev, struct Qdisc *sch,
+			   struct Qdisc *new, struct Qdisc *old,
+			   enum tc_setup_type type, void *type_data,
+			   struct netlink_ext_ack *extack)
+{
+}
 #endif
 struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
 			  const struct Qdisc_ops *ops,

net/sched/sch_api.c

@@ -831,6 +831,35 @@ int qdisc_offload_dump_helper(struct Qdisc *sch, enum tc_setup_type type,
 }
 EXPORT_SYMBOL(qdisc_offload_dump_helper);
 
+void qdisc_offload_graft_helper(struct net_device *dev, struct Qdisc *sch,
+				struct Qdisc *new, struct Qdisc *old,
+				enum tc_setup_type type, void *type_data,
+				struct netlink_ext_ack *extack)
+{
+	bool any_qdisc_is_offloaded;
+	int err;
+
+	if (!tc_can_offload(dev) || !dev->netdev_ops->ndo_setup_tc)
+		return;
+
+	err = dev->netdev_ops->ndo_setup_tc(dev, type, type_data);
+
+	/* Don't report error if the graft is part of destroy operation. */
+	if (!err || !new || new == &noop_qdisc)
+		return;
+
+	/* Don't report error if the parent, the old child and the new
+	 * one are not offloaded.
+	 */
+	any_qdisc_is_offloaded = new->flags & TCQ_F_OFFLOADED;
+	any_qdisc_is_offloaded |= sch && sch->flags & TCQ_F_OFFLOADED;
+	any_qdisc_is_offloaded |= old && old->flags & TCQ_F_OFFLOADED;
+
+	if (any_qdisc_is_offloaded)
+		NL_SET_ERR_MSG(extack, "Offloading graft operation failed.");
+}
+EXPORT_SYMBOL(qdisc_offload_graft_helper);
+
 static int tc_fill_qdisc(struct sk_buff *skb, struct Qdisc *q, u32 clid,
 			 u32 portid, u32 seq, u16 flags, int event)
 {

net/sched/sch_prio.c

@@ -295,43 +295,22 @@ static int prio_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
 {
 	struct prio_sched_data *q = qdisc_priv(sch);
 	struct tc_prio_qopt_offload graft_offload;
-	struct net_device *dev = qdisc_dev(sch);
 	unsigned long band = arg - 1;
-	bool any_qdisc_is_offloaded;
-	int err;
 
 	if (new == NULL)
 		new = &noop_qdisc;
 
 	*old = qdisc_replace(sch, new, &q->queues[band]);
 
-	if (!tc_can_offload(dev))
-		return 0;
-
 	graft_offload.handle = sch->handle;
 	graft_offload.parent = sch->parent;
 	graft_offload.graft_params.band = band;
 	graft_offload.graft_params.child_handle = new->handle;
 	graft_offload.command = TC_PRIO_GRAFT;
 
-	err = dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_PRIO,
-					    &graft_offload);
-
-	/* Don't report error if the graft is part of destroy operation. */
-	if (err && new != &noop_qdisc) {
-		/* Don't report error if the parent, the old child and the new
-		 * one are not offloaded.
-		 */
-		any_qdisc_is_offloaded = sch->flags & TCQ_F_OFFLOADED;
-		any_qdisc_is_offloaded |= new->flags & TCQ_F_OFFLOADED;
-		if (*old)
-			any_qdisc_is_offloaded |= (*old)->flags &
-						   TCQ_F_OFFLOADED;
-
-		if (any_qdisc_is_offloaded)
-			NL_SET_ERR_MSG(extack, "Offloading graft operation failed.");
-	}
-
+	qdisc_offload_graft_helper(qdisc_dev(sch), sch, new, *old,
+				   TC_SETUP_QDISC_PRIO, &graft_offload,
+				   extack);
 	return 0;
 }