Re: [PATCH] net: udp: increase UDP_MIB_RCVBUFERRORS when ENOBUFS

The error returned from __udp_enqueue_schedule_skb is ENOMEM or ENOBUFS.
For now, only ENOMEM is counted into UDP_MIB_RCVBUFERRORS in
__udp_queue_rcv_skb. UDP_MIB_RCVBUFERRORS should count all of the
failed skb because of memory errors during udp receiving, not just because of the limit of sock receive queue. We can see this
in __udp4_lib_mcast_deliver:

		nskb = skb_clone(skb, GFP_ATOMIC);

		if (unlikely(!nskb)) {
			atomic_inc(&sk->sk_drops);
			__UDP_INC_STATS(net, UDP_MIB_RCVBUFERRORS,
					IS_UDPLITE(sk));
			__UDP_INC_STATS(net, UDP_MIB_INERRORS,
					IS_UDPLITE(sk));
			continue;
		}

See, UDP_MIB_RCVBUFERRORS is increased when skb clone failed. From this
point, ENOBUFS from __udp_enqueue_schedule_skb should be counted, too.
It means that the buffer used by all of the UDP sock is to the limit, and
it ought to be counted.

Signed-off-by: Menglong Dong <redacted>
---
 net/ipv4/udp.c | 4 +---
 net/ipv6/udp.c | 4 +---
 2 files changed, 2 insertions(+), 6 deletions(-)

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 09f0a23d1a01..49a69d8d55b3 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c

@@ -2035,9 +2035,7 @@ static int __udp_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
 		int is_udplite = IS_UDPLITE(sk);
 
 		/* Note that an ENOMEM error is charged twice */
-		if (rc == -ENOMEM)
-			UDP_INC_STATS(sock_net(sk), UDP_MIB_RCVBUFERRORS,
-					is_udplite);
+		UDP_INC_STATS(sock_net(sk), UDP_MIB_RCVBUFERRORS, is_udplite);
 		UDP_INC_STATS(sock_net(sk), UDP_MIB_INERRORS, is_udplite);
 		kfree_skb(skb);
 		trace_udp_fail_queue_rcv_skb(rc, sk);

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 29d9691359b9..d5e23b150fd9 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c

@@ -634,9 +634,7 @@ static int __udpv6_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
 		int is_udplite = IS_UDPLITE(sk);
 
 		/* Note that an ENOMEM error is charged twice */
-		if (rc == -ENOMEM)
-			UDP6_INC_STATS(sock_net(sk),
-					 UDP_MIB_RCVBUFERRORS, is_udplite);
+		UDP6_INC_STATS(sock_net(sk), UDP_MIB_RCVBUFERRORS, is_udplite);
 		UDP6_INC_STATS(sock_net(sk), UDP_MIB_INERRORS, is_udplite);
 		kfree_skb(skb);
 		return -1;