net: sched: cls_flower: implement offload tcf_proto_op

Add the reoffload tcf_proto_op in flower to generate an offload message
for each filter in the given tcf_proto. Call the specified callback with
this new offload message. The function only returns an error if the
callback rejects adding a 'hardware only' rule.

A filter contains a flag to indicate if it is in hardware or not. To
ensure the reoffload function properly maintains this flag, keep a
reference counter for the number of instances of the filter that are in
hardware. Only update the flag when this counter changes from or to 0. Add
a generic helper function to implement this behaviour.

Signed-off-by: John Hurley <john.hurley@netronome.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/sch_generic.h

@@ -336,6 +336,21 @@ static inline void tcf_block_offload_dec(struct tcf_block *block, u32 *flags)
 	block->offloadcnt--;
 }
 
+static inline void
+tc_cls_offload_cnt_update(struct tcf_block *block, unsigned int *cnt,
+			  u32 *flags, bool add)
+{
+	if (add) {
+		if (!*cnt)
+			tcf_block_offload_inc(block, flags);
+		(*cnt)++;
+	} else {
+		(*cnt)--;
+		if (!*cnt)
+			tcf_block_offload_dec(block, flags);
+	}
+}
+
 static inline void qdisc_cb_private_validate(const struct sk_buff *skb, int sz)
 {
 	struct qdisc_skb_cb *qcb;

net/sched/cls_flower.c

@@ -87,6 +87,7 @@ struct cls_fl_filter {
 	struct list_head list;
 	u32 handle;
 	u32 flags;
+	unsigned int in_hw_count;
 	struct rcu_work rwork;
 	struct net_device *hw_dev;
 };
@@ -289,6 +290,7 @@ static int fl_hw_replace_filter(struct tcf_proto *tp,
 		fl_hw_destroy_filter(tp, f, NULL);
 		return err;
 	} else if (err > 0) {
+		f->in_hw_count = err;
 		tcf_block_offload_inc(block, &f->flags);
 	}
 
@@ -1087,6 +1089,47 @@ static void fl_walk(struct tcf_proto *tp, struct tcf_walker *arg)
 	}
 }
 
+static int fl_reoffload(struct tcf_proto *tp, bool add, tc_setup_cb_t *cb,
+			void *cb_priv, struct netlink_ext_ack *extack)
+{
+	struct cls_fl_head *head = rtnl_dereference(tp->root);
+	struct tc_cls_flower_offload cls_flower = {};
+	struct tcf_block *block = tp->chain->block;
+	struct fl_flow_mask *mask;
+	struct cls_fl_filter *f;
+	int err;
+
+	list_for_each_entry(mask, &head->masks, list) {
+		list_for_each_entry(f, &mask->filters, list) {
+			if (tc_skip_hw(f->flags))
+				continue;
+
+			tc_cls_common_offload_init(&cls_flower.common, tp,
+						   f->flags, extack);
+			cls_flower.command = add ?
+				TC_CLSFLOWER_REPLACE : TC_CLSFLOWER_DESTROY;
+			cls_flower.cookie = (unsigned long)f;
+			cls_flower.dissector = &mask->dissector;
+			cls_flower.mask = &f->mkey;
+			cls_flower.key = &f->key;
+			cls_flower.exts = &f->exts;
+			cls_flower.classid = f->res.classid;
+
+			err = cb(TC_SETUP_CLSFLOWER, &cls_flower, cb_priv);
+			if (err) {
+				if (add && tc_skip_sw(f->flags))
+					return err;
+				continue;
+			}
+
+			tc_cls_offload_cnt_update(block, &f->in_hw_count,
+						  &f->flags, add);
+		}
+	}
+
+	return 0;
+}
+
 static int fl_dump_key_val(struct sk_buff *skb,
 			   void *val, int val_type,
 			   void *mask, int mask_type, int len)
@@ -1438,6 +1481,7 @@ static struct tcf_proto_ops cls_fl_ops __read_mostly = {
 	.change		= fl_change,
 	.delete		= fl_delete,
 	.walk		= fl_walk,
+	.reoffload	= fl_reoffload,
 	.dump		= fl_dump,
 	.bind_class	= fl_bind_class,
 	.owner		= THIS_MODULE,