[PATCH nf-next 2/2] netfilter: flowtable: update netdev stats with HW_OFFLOAD flows

[Ahmed Zaki <anzaki@gmail.com>]

SNMP-based network monitoring systems (and maybe other tools) rely on
netdev stats to report the network traffic. We currently do not update
the netdev stats with the offloaded flows stats which creates
discrepancies in the stats with some of these devices inside a bigger
network.

Update the nedev stats with the hardware offloaded flows' stats. The
stats are updated periodically in flow_offload_work_stats() and also
once in flow_offload_work_del() before the flow is deleted. For this,
flow_offload_work_del() had to be moved below flow_offload_tuple_stats()

Signed-off-by: Ahmed Zaki <anzaki@gmail.com>
---
 net/netfilter/nf_flow_table_offload.c | 59 ++++++++++++++++++++++++---
 1 file changed, 53 insertions(+), 6 deletions(-)

diff --git a/net/netfilter/nf_flow_table_offload.c b/net/netfilter/nf_flow_table_offload.c
index b2e4fb6fa011..fb325d4a1131 100644
--- a/net/netfilter/nf_flow_table_offload.c
+++ b/net/netfilter/nf_flow_table_offload.c
@@ -925,13 +925,41 @@ static void flow_offload_work_add(struct flow_offload_work *offload)
 	nf_flow_offload_destroy(flow_rule);
 }
 
-static void flow_offload_work_del(struct flow_offload_work *offload)
+static void flow_offload_netdev_update(struct flow_offload_work *offload,
+				       struct flow_stats *stats)
 {
-	clear_bit(IPS_HW_OFFLOAD_BIT, &offload->flow->ct->status);
-	flow_offload_tuple_del(offload, FLOW_OFFLOAD_DIR_ORIGINAL);
-	if (test_bit(NF_FLOW_HW_BIDIRECTIONAL, &offload->flow->flags))
-		flow_offload_tuple_del(offload, FLOW_OFFLOAD_DIR_REPLY);
-	set_bit(NF_FLOW_HW_DEAD, &offload->flow->flags);
+	const struct flow_offload_tuple *tuple;
+	struct net_device *indev, *outdev;
+	struct net *net;
+
+	rcu_read_lock();
+	net = read_pnet(&offload->flowtable->net);
+	if (stats[0].pkts) {
+		tuple = &offload->flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple;
+		indev  = dev_get_by_index_rcu(net, tuple->iifidx);
+		if (indev)
+			dev_sw_netstats_rx_add(indev,
+					       stats[0].pkts, stats[0].bytes);
+
+		outdev = dev_get_by_index_rcu(net, tuple->out.ifidx);
+		if (outdev)
+			dev_sw_netstats_tx_add(outdev,
+					       stats[0].pkts, stats[0].bytes);
+	}
+
+	if (stats[1].pkts) {
+		tuple = &offload->flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple;
+		indev  = dev_get_by_index_rcu(net, tuple->iifidx);
+		if (indev)
+			dev_sw_netstats_rx_add(indev,
+					       stats[1].pkts, stats[1].bytes);
+
+		outdev = dev_get_by_index_rcu(net, tuple->out.ifidx);
+		if (outdev)
+			dev_sw_netstats_tx_add(outdev,
+					       stats[1].pkts, stats[1].bytes);
+	}
+	rcu_read_unlock();
 }
 
 static void flow_offload_tuple_stats(struct flow_offload_work *offload,
@@ -968,6 +996,25 @@ static void flow_offload_work_stats(struct flow_offload_work *offload)
 				       FLOW_OFFLOAD_DIR_REPLY,
 				       stats[1].pkts, stats[1].bytes);
 	}
+
+	flow_offload_netdev_update(offload, stats);
+}
+
+static void flow_offload_work_del(struct flow_offload_work *offload)
+{
+	struct flow_stats stats[FLOW_OFFLOAD_DIR_MAX] = {};
+
+	flow_offload_tuple_stats(offload, FLOW_OFFLOAD_DIR_ORIGINAL, &stats[0]);
+	if (test_bit(NF_FLOW_HW_BIDIRECTIONAL, &offload->flow->flags))
+		flow_offload_tuple_stats(offload, FLOW_OFFLOAD_DIR_REPLY,
+					 &stats[1]);
+	flow_offload_netdev_update(offload, stats);
+
+	clear_bit(IPS_HW_OFFLOAD_BIT, &offload->flow->ct->status);
+	flow_offload_tuple_del(offload, FLOW_OFFLOAD_DIR_ORIGINAL);
+	if (test_bit(NF_FLOW_HW_BIDIRECTIONAL, &offload->flow->flags))
+		flow_offload_tuple_del(offload, FLOW_OFFLOAD_DIR_REPLY);
+	set_bit(NF_FLOW_HW_DEAD, &offload->flow->flags);
 }
 
 static void flow_offload_work_handler(struct work_struct *work)
-- 
2.43.0