nfp: flower: support stats update for merge flows

With the merging of 2 sub flows, a new 'merge' flow will be created and
written to FW. The TC layer is unaware that the merge flow exists and will
request stats from the sub flows. Conversely, the FW treats a merge rule
the same as any other rule and sends stats updates to the NFP driver.

Add links between merge flows and their sub flows. Use these links to pass
merge flow stats updates from FW to the underlying sub flows, ensuring TC
stats requests are handled correctly. The updating of sub flow stats is
done on (the less time critcal) TC stats requests rather than on FW stats
update.
Signed-off-by: John Hurley <john.hurley@netronome.com>
Signed-off-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/netronome/nfp/flower/main.h

@@ -252,6 +252,24 @@ struct nfp_fl_payload {
 	char *unmasked_data;
 	char *mask_data;
 	char *action_data;
+	struct list_head linked_flows;
+};
+
+struct nfp_fl_payload_link {
+	/* A link contains a pointer to a merge flow and an associated sub_flow.
+	 * Each merge flow will feature in 2 links to its underlying sub_flows.
+	 * A sub_flow will have at least 1 link to a merge flow or more if it
+	 * has been used to create multiple merge flows.
+	 *
+	 * For a merge flow, 'linked_flows' in its nfp_fl_payload struct lists
+	 * all links to sub_flows (sub_flow.flow) via merge.list.
+	 * For a sub_flow, 'linked_flows' gives all links to merge flows it has
+	 * formed (merge_flow.flow) via sub_flow.list.
+	 */
+	struct {
+		struct list_head list;
+		struct nfp_fl_payload *flow;
+	} merge_flow, sub_flow;
 };
 
 extern const struct rhashtable_params nfp_flower_table_params;

drivers/net/ethernet/netronome/nfp/flower/offload.c

@@ -398,6 +398,7 @@ nfp_flower_allocate_new(struct nfp_fl_key_ls *key_layer)
 
 	flow_pay->nfp_tun_ipv4_addr = 0;
 	flow_pay->meta.flags = 0;
+	INIT_LIST_HEAD(&flow_pay->linked_flows);
 
 	return flow_pay;
 
@@ -716,6 +717,43 @@ nfp_flower_merge_action(struct nfp_fl_payload *sub_flow1,
 	return 0;
 }
 
+/* Flow link code should only be accessed under RTNL. */
+static void nfp_flower_unlink_flow(struct nfp_fl_payload_link *link)
+{
+	list_del(&link->merge_flow.list);
+	list_del(&link->sub_flow.list);
+	kfree(link);
+}
+
+static void nfp_flower_unlink_flows(struct nfp_fl_payload *merge_flow,
+				    struct nfp_fl_payload *sub_flow)
+{
+	struct nfp_fl_payload_link *link;
+
+	list_for_each_entry(link, &merge_flow->linked_flows, merge_flow.list)
+		if (link->sub_flow.flow == sub_flow) {
+			nfp_flower_unlink_flow(link);
+			return;
+		}
+}
+
+static int nfp_flower_link_flows(struct nfp_fl_payload *merge_flow,
+				 struct nfp_fl_payload *sub_flow)
+{
+	struct nfp_fl_payload_link *link;
+
+	link = kmalloc(sizeof(*link), GFP_KERNEL);
+	if (!link)
+		return -ENOMEM;
+
+	link->merge_flow.flow = merge_flow;
+	list_add_tail(&link->merge_flow.list, &merge_flow->linked_flows);
+	link->sub_flow.flow = sub_flow;
+	list_add_tail(&link->sub_flow.list, &sub_flow->linked_flows);
+
+	return 0;
+}
+
 /**
  * nfp_flower_merge_offloaded_flows() - Merge 2 existing flows to single flow.
  * @app:	Pointer to the APP handle
@@ -764,8 +802,19 @@ int nfp_flower_merge_offloaded_flows(struct nfp_app *app,
 	if (err)
 		goto err_destroy_merge_flow;
 
+	err = nfp_flower_link_flows(merge_flow, sub_flow1);
+	if (err)
+		goto err_destroy_merge_flow;
+
+	err = nfp_flower_link_flows(merge_flow, sub_flow2);
+	if (err)
+		goto err_unlink_sub_flow1;
+
 	err = -EOPNOTSUPP;
 
+	nfp_flower_unlink_flows(merge_flow, sub_flow2);
+err_unlink_sub_flow1:
+	nfp_flower_unlink_flows(merge_flow, sub_flow1);
 err_destroy_merge_flow:
 	kfree(merge_flow->action_data);
 	kfree(merge_flow->mask_data);
@@ -913,6 +962,52 @@ nfp_flower_del_offload(struct nfp_app *app, struct net_device *netdev,
 	return err;
 }
 
+static void
+__nfp_flower_update_merge_stats(struct nfp_app *app,
+				struct nfp_fl_payload *merge_flow)
+{
+	struct nfp_flower_priv *priv = app->priv;
+	struct nfp_fl_payload_link *link;
+	struct nfp_fl_payload *sub_flow;
+	u64 pkts, bytes, used;
+	u32 ctx_id;
+
+	ctx_id = be32_to_cpu(merge_flow->meta.host_ctx_id);
+	pkts = priv->stats[ctx_id].pkts;
+	/* Do not cycle subflows if no stats to distribute. */
+	if (!pkts)
+		return;
+	bytes = priv->stats[ctx_id].bytes;
+	used = priv->stats[ctx_id].used;
+
+	/* Reset stats for the merge flow. */
+	priv->stats[ctx_id].pkts = 0;
+	priv->stats[ctx_id].bytes = 0;
+
+	/* The merge flow has received stats updates from firmware.
+	 * Distribute these stats to all subflows that form the merge.
+	 * The stats will collected from TC via the subflows.
+	 */
+	list_for_each_entry(link, &merge_flow->linked_flows, merge_flow.list) {
+		sub_flow = link->sub_flow.flow;
+		ctx_id = be32_to_cpu(sub_flow->meta.host_ctx_id);
+		priv->stats[ctx_id].pkts += pkts;
+		priv->stats[ctx_id].bytes += bytes;
+		max_t(u64, priv->stats[ctx_id].used, used);
+	}
+}
+
+static void
+nfp_flower_update_merge_stats(struct nfp_app *app,
+			      struct nfp_fl_payload *sub_flow)
+{
+	struct nfp_fl_payload_link *link;
+
+	/* Get merge flows that the subflow forms to distribute their stats. */
+	list_for_each_entry(link, &sub_flow->linked_flows, sub_flow.list)
+		__nfp_flower_update_merge_stats(app, link->merge_flow.flow);
+}
+
 /**
  * nfp_flower_get_stats() - Populates flow stats obtained from hardware.
  * @app:	Pointer to the APP handle
@@ -939,6 +1034,10 @@ nfp_flower_get_stats(struct nfp_app *app, struct net_device *netdev,
 	ctx_id = be32_to_cpu(nfp_flow->meta.host_ctx_id);
 
 	spin_lock_bh(&priv->stats_lock);
+	/* If request is for a sub_flow, update stats from merged flows. */
+	if (!list_empty(&nfp_flow->linked_flows))
+		nfp_flower_update_merge_stats(app, nfp_flow);
+
 	flow_stats_update(&flow->stats, priv->stats[ctx_id].bytes,
 			  priv->stats[ctx_id].pkts, priv->stats[ctx_id].used);