net: sched: cls_u32: implement offload tcf_proto_op

Add the offload tcf_proto_op in cls_u32 to generate an offload message for
each filter and the hashtable 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 offload 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.
Signed-off-by: John Hurley <john.hurley@netronome.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/cls_u32.c

@@ -62,6 +62,7 @@ struct tc_u_knode {
 	struct tc_u32_pcnt __percpu *pf;
 #endif
 	u32			flags;
+	unsigned int		in_hw_count;
 #ifdef CONFIG_CLS_U32_MARK
 	u32			val;
 	u32			mask;
@@ -571,6 +572,7 @@ static int u32_replace_hw_knode(struct tcf_proto *tp, struct tc_u_knode *n,
 		u32_remove_hw_knode(tp, n, NULL);
 		return err;
 	} else if (err > 0) {
+		n->in_hw_count = err;
 		tcf_block_offload_inc(block, &n->flags);
 	}
 
@@ -1199,6 +1201,114 @@ static void u32_walk(struct tcf_proto *tp, struct tcf_walker *arg)
 	}
 }
 
+static int u32_reoffload_hnode(struct tcf_proto *tp, struct tc_u_hnode *ht,
+			       bool add, tc_setup_cb_t *cb, void *cb_priv,
+			       struct netlink_ext_ack *extack)
+{
+	struct tc_cls_u32_offload cls_u32 = {};
+	int err;
+
+	tc_cls_common_offload_init(&cls_u32.common, tp, ht->flags, extack);
+	cls_u32.command = add ? TC_CLSU32_NEW_HNODE : TC_CLSU32_DELETE_HNODE;
+	cls_u32.hnode.divisor = ht->divisor;
+	cls_u32.hnode.handle = ht->handle;
+	cls_u32.hnode.prio = ht->prio;
+
+	err = cb(TC_SETUP_CLSU32, &cls_u32, cb_priv);
+	if (err && add && tc_skip_sw(ht->flags))
+		return err;
+
+	return 0;
+}
+
+static int u32_reoffload_knode(struct tcf_proto *tp, struct tc_u_knode *n,
+			       bool add, tc_setup_cb_t *cb, void *cb_priv,
+			       struct netlink_ext_ack *extack)
+{
+	struct tc_u_hnode *ht = rtnl_dereference(n->ht_down);
+	struct tcf_block *block = tp->chain->block;
+	struct tc_cls_u32_offload cls_u32 = {};
+	int err;
+
+	tc_cls_common_offload_init(&cls_u32.common, tp, n->flags, extack);
+	cls_u32.command = add ?
+		TC_CLSU32_REPLACE_KNODE : TC_CLSU32_DELETE_KNODE;
+	cls_u32.knode.handle = n->handle;
+
+	if (add) {
+		cls_u32.knode.fshift = n->fshift;
+#ifdef CONFIG_CLS_U32_MARK
+		cls_u32.knode.val = n->val;
+		cls_u32.knode.mask = n->mask;
+#else
+		cls_u32.knode.val = 0;
+		cls_u32.knode.mask = 0;
+#endif
+		cls_u32.knode.sel = &n->sel;
+		cls_u32.knode.exts = &n->exts;
+		if (n->ht_down)
+			cls_u32.knode.link_handle = ht->handle;
+	}
+
+	err = cb(TC_SETUP_CLSU32, &cls_u32, cb_priv);
+	if (err) {
+		if (add && tc_skip_sw(n->flags))
+			return err;
+		return 0;
+	}
+
+	tc_cls_offload_cnt_update(block, &n->in_hw_count, &n->flags, add);
+
+	return 0;
+}
+
+static int u32_reoffload(struct tcf_proto *tp, bool add, tc_setup_cb_t *cb,
+			 void *cb_priv, struct netlink_ext_ack *extack)
+{
+	struct tc_u_common *tp_c = tp->data;
+	struct tc_u_hnode *ht;
+	struct tc_u_knode *n;
+	unsigned int h;
+	int err;
+
+	for (ht = rtnl_dereference(tp_c->hlist);
+	     ht;
+	     ht = rtnl_dereference(ht->next)) {
+		if (ht->prio != tp->prio)
+			continue;
+
+		/* When adding filters to a new dev, try to offload the
+		 * hashtable first. When removing, do the filters before the
+		 * hashtable.
+		 */
+		if (add && !tc_skip_hw(ht->flags)) {
+			err = u32_reoffload_hnode(tp, ht, add, cb, cb_priv,
+						  extack);
+			if (err)
+				return err;
+		}
+
+		for (h = 0; h <= ht->divisor; h++) {
+			for (n = rtnl_dereference(ht->ht[h]);
+			     n;
+			     n = rtnl_dereference(n->next)) {
+				if (tc_skip_hw(n->flags))
+					continue;
+
+				err = u32_reoffload_knode(tp, n, add, cb,
+							  cb_priv, extack);
+				if (err)
+					return err;
+			}
+		}
+
+		if (!add && !tc_skip_hw(ht->flags))
+			u32_reoffload_hnode(tp, ht, add, cb, cb_priv, extack);
+	}
+
+	return 0;
+}
+
 static void u32_bind_class(void *fh, u32 classid, unsigned long cl)
 {
 	struct tc_u_knode *n = fh;
@@ -1336,6 +1446,7 @@ static struct tcf_proto_ops cls_u32_ops __read_mostly = {
 	.change		=	u32_change,
 	.delete		=	u32_delete,
 	.walk		=	u32_walk,
+	.reoffload	=	u32_reoffload,
 	.dump		=	u32_dump,
 	.bind_class	=	u32_bind_class,
 	.owner		=	THIS_MODULE,