[PATCH net-next] udp: add drop count for packets in udp_prod_queue

[Mahdi Faramarzpour <mahdifrmx@gmail.com>]

This commit adds SNMP drop count increment for the packets in
per NUMA queues which were introduced in commit b650bf0977d3
("udp: remove busylock and add per NUMA queues").

Signed-off-by: Mahdi Faramarzpour <mahdifrmx@gmail.com>
---
 net/ipv4/udp.c | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index ffe074cb5..19ab44e46 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1709,6 +1709,11 @@ int __udp_enqueue_schedule_skb(struct sock *sk, struct sk_buff *skb)
 	int dropcount;
 	int nb = 0;
 
+	struct {
+		int mem4;
+		int mem6;
+	} err_count = { 0, 0 };
+
 	rmem = atomic_read(&sk->sk_rmem_alloc);
 	rcvbuf = READ_ONCE(sk->sk_rcvbuf);
 	size = skb->truesize;
@@ -1760,6 +1765,10 @@ int __udp_enqueue_schedule_skb(struct sock *sk, struct sk_buff *skb)
 		total_size += size;
 		err = udp_rmem_schedule(sk, size);
 		if (unlikely(err)) {
+			if (skb->protocol == htons(ETH_P_IP))
+				err_count.mem4++;
+			else
+				err_count.mem6++;
 			/*  Free the skbs outside of locked section. */
 			skb->next = to_drop;
 			to_drop = skb;
@@ -1797,10 +1806,18 @@ int __udp_enqueue_schedule_skb(struct sock *sk, struct sk_buff *skb)
 			skb = to_drop;
 			to_drop = skb->next;
 			skb_mark_not_on_list(skb);
-			/* TODO: update SNMP values. */
 			sk_skb_reason_drop(sk, skb, SKB_DROP_REASON_PROTO_MEM);
 		}
 		numa_drop_add(&udp_sk(sk)->drop_counters, nb);
+
+		SNMP_ADD_STATS(__UDPX_MIB(sk, true), UDP_MIB_MEMERRORS,
+			       err_count.mem4);
+		SNMP_ADD_STATS(__UDPX_MIB(sk, true), UDP_MIB_INERRORS,
+			       err_count.mem4);
+		SNMP_ADD_STATS(__UDPX_MIB(sk, false), UDP_MIB_MEMERRORS,
+			       err_count.mem6);
+		SNMP_ADD_STATS(__UDPX_MIB(sk, false), UDP_MIB_INERRORS,
+			       err_count.mem6);
 	}
 
 	atomic_sub(total_size, &udp_prod_queue->rmem_alloc);
-- 
2.34.1