From 907cdda5205b012eec7513f66713749b293188c9 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 19 Mar 2010 05:37:18 +0000 Subject: [PATCH] tcp: Add SNMP counter for DEFER_ACCEPT Its currently hard to diagnose when ACK frames are dropped because an application set TCP_DEFER_ACCEPT on its listening socket. See http://bugzilla.kernel.org/show_bug.cgi?id=15507 This patch adds a SNMP value, named TCPDeferAcceptDrop netstat -s | grep TCPDeferAcceptDrop TCPDeferAcceptDrop: 0 This counter is incremented every time we drop a pure ACK frame received by a socket in SYN_RECV state because its SYNACK retrans count is lower than defer_accept value. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- include/linux/snmp.h | 1 + net/ipv4/proc.c | 1 + net/ipv4/tcp_minisocks.c | 1 + 3 files changed, 3 insertions(+) diff --git a/include/linux/snmp.h b/include/linux/snmp.h index 4435d10..d2a9aa3 100644 --- a/include/linux/snmp.h +++ b/include/linux/snmp.h @@ -227,6 +227,7 @@ enum LINUX_MIB_SACKSHIFTFALLBACK, LINUX_MIB_TCPBACKLOGDROP, LINUX_MIB_TCPMINTTLDROP, /* RFC 5082 */ + LINUX_MIB_TCPDEFERACCEPTDROP, __LINUX_MIB_MAX }; diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c index 4f1f337..3dc9914 100644 --- a/net/ipv4/proc.c +++ b/net/ipv4/proc.c @@ -251,6 +251,7 @@ static const struct snmp_mib snmp4_net_list[] = { SNMP_MIB_ITEM("TCPSackShiftFallback", LINUX_MIB_SACKSHIFTFALLBACK), SNMP_MIB_ITEM("TCPBacklogDrop", LINUX_MIB_TCPBACKLOGDROP), SNMP_MIB_ITEM("TCPMinTTLDrop", LINUX_MIB_TCPMINTTLDROP), + SNMP_MIB_ITEM("TCPDeferAcceptDrop", LINUX_MIB_TCPDEFERACCEPTDROP), SNMP_MIB_SENTINEL }; diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c index 4199bc6..32f9627 100644 --- a/net/ipv4/tcp_minisocks.c +++ b/net/ipv4/tcp_minisocks.c @@ -671,6 +671,7 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb, if (req->retrans < inet_csk(sk)->icsk_accept_queue.rskq_defer_accept && TCP_SKB_CB(skb)->end_seq == tcp_rsk(req)->rcv_isn + 1) { inet_rsk(req)->acked = 1; + NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPDEFERACCEPTDROP); return NULL; } -- 1.8.2.3