net: udp: introduce UDP_MIB_MEMERRORS for udp_mem

When udp_memory_allocated is at the limit, __udp_enqueue_schedule_skb
will return a -ENOBUFS, and skb will be dropped in __udp_queue_rcv_skb
without any counters being done. It's hard to find out what happened
once this happen.

So we introduce a UDP_MIB_MEMERRORS to do this job. Well, this change
looks friendly to the existing users, such as netstat:

$ netstat -u -s
Udp:
    0 packets received
    639 packets to unknown port received.
    158689 packet receive errors
    180022 packets sent
    RcvbufErrors: 20930
    MemErrors: 137759
UdpLite:
IpExt:
    InOctets: 257426235
    OutOctets: 257460598
    InNoECTPkts: 181177

v2:
- Fix some alignment problems

Signed-off-by: Menglong Dong <dong.menglong@zte.com.cn>
Link: https://lore.kernel.org/r/1604627354-43207-1-git-send-email-dong.menglong@zte.com.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/uapi/linux/snmp.h b/include/uapi/linux/snmp.h
index f84e7bc..26fc60c 100644 (file)
--- a/include/uapi/linux/snmp.h
+++ b/include/uapi/linux/snmp.h
@@ -159,6 +159,7 @@ enum
        UDP_MIB_SNDBUFERRORS,                   /* SndbufErrors */
        UDP_MIB_CSUMERRORS,                     /* InCsumErrors */
        UDP_MIB_IGNOREDMULTI,                   /* IgnoredMulti */
+       UDP_MIB_MEMERRORS,                      /* MemErrors */
        __UDP_MIB_MAX
 };
 

diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
index 8d5e169..63cd370 100644 (file)
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -167,6 +167,7 @@ static const struct snmp_mib snmp4_udp_list[] = {
        SNMP_MIB_ITEM("SndbufErrors", UDP_MIB_SNDBUFERRORS),
        SNMP_MIB_ITEM("InCsumErrors", UDP_MIB_CSUMERRORS),
        SNMP_MIB_ITEM("IgnoredMulti", UDP_MIB_IGNOREDMULTI),
+       SNMP_MIB_ITEM("MemErrors", UDP_MIB_MEMERRORS),
        SNMP_MIB_SENTINEL
 };
 

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index ca04a8a..1e2e73a 100644 (file)
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -2038,6 +2038,9 @@ static int __udp_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
                if (rc == -ENOMEM)
                        UDP_INC_STATS(sock_net(sk), UDP_MIB_RCVBUFERRORS,
                                        is_udplite);
+               else
+                       UDP_INC_STATS(sock_net(sk), UDP_MIB_MEMERRORS,
+                                     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/proc.c b/net/ipv6/proc.c
index bbff3e0..d6306aa 100644 (file)
--- a/net/ipv6/proc.c
+++ b/net/ipv6/proc.c
@@ -126,6 +126,7 @@ static const struct snmp_mib snmp6_udp6_list[] = {
        SNMP_MIB_ITEM("Udp6SndbufErrors", UDP_MIB_SNDBUFERRORS),
        SNMP_MIB_ITEM("Udp6InCsumErrors", UDP_MIB_CSUMERRORS),
        SNMP_MIB_ITEM("Udp6IgnoredMulti", UDP_MIB_IGNOREDMULTI),
+       SNMP_MIB_ITEM("Udp6MemErrors", UDP_MIB_MEMERRORS),
        SNMP_MIB_SENTINEL
 };
 
@@ -137,6 +138,7 @@ static const struct snmp_mib snmp6_udplite6_list[] = {
        SNMP_MIB_ITEM("UdpLite6RcvbufErrors", UDP_MIB_RCVBUFERRORS),
        SNMP_MIB_ITEM("UdpLite6SndbufErrors", UDP_MIB_SNDBUFERRORS),
        SNMP_MIB_ITEM("UdpLite6InCsumErrors", UDP_MIB_CSUMERRORS),
+       SNMP_MIB_ITEM("UdpLite6MemErrors", UDP_MIB_MEMERRORS),
        SNMP_MIB_SENTINEL
 };
 

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index cde9b88..559611b 100644 (file)
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -637,6 +637,9 @@ static int __udpv6_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
                if (rc == -ENOMEM)
                        UDP6_INC_STATS(sock_net(sk),
                                         UDP_MIB_RCVBUFERRORS, is_udplite);
+               else
+                       UDP6_INC_STATS(sock_net(sk),
+                                      UDP_MIB_MEMERRORS, is_udplite);
                UDP6_INC_STATS(sock_net(sk), UDP_MIB_INERRORS, is_udplite);
                kfree_skb(skb);
                return -1;