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tcp: add TCPWinProbe and TCPKeepAlive SNMP counters

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Diagnosing problems related to Window Probes has been hard because
we lack a counter.

TCPWinProbe counts the number of ACK packets a sender has to send
at regular intervals to make sure a reverse ACK packet opening back
a window had not been lost.

TCPKeepAlive counts the number of ACK packets sent to keep TCP
flows alive (SO_KEEPALIVE)

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Acked-by: Nandita Dukkipati <nanditad@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2015-05-06 14:26:25 -07:00 committed by David S. Miller
parent 21c8fe9915
commit e520af48c7
5 changed files with 13 additions and 8 deletions
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2
include/net/tcp.h
View file

@ -527,7 +527,7 @@ int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int, gfp_t);
void tcp_send_probe0(struct sock *);
void tcp_send_partial(struct sock *);
int tcp_write_wakeup(struct sock *);
int tcp_write_wakeup(struct sock *, int mib);
void tcp_send_fin(struct sock *sk);
void tcp_send_active_reset(struct sock *sk, gfp_t priority);
int tcp_send_synack(struct sock *);

2
include/uapi/linux/snmp.h
View file

@ -276,6 +276,8 @@ enum
LINUX_MIB_TCPACKSKIPPEDFINWAIT2, /* TCPACKSkippedFinWait2 */
LINUX_MIB_TCPACKSKIPPEDTIMEWAIT, /* TCPACKSkippedTimeWait */
LINUX_MIB_TCPACKSKIPPEDCHALLENGE, /* TCPACKSkippedChallenge */
LINUX_MIB_TCPWINPROBE, /* TCPWinProbe */
LINUX_MIB_TCPKEEPALIVE, /* TCPKeepAlive */
__LINUX_MIB_MAX
};

2
net/ipv4/proc.c
View file

@ -298,6 +298,8 @@ static const struct snmp_mib snmp4_net_list[] = {
SNMP_MIB_ITEM("TCPACKSkippedFinWait2", LINUX_MIB_TCPACKSKIPPEDFINWAIT2),
SNMP_MIB_ITEM("TCPACKSkippedTimeWait", LINUX_MIB_TCPACKSKIPPEDTIMEWAIT),
SNMP_MIB_ITEM("TCPACKSkippedChallenge", LINUX_MIB_TCPACKSKIPPEDCHALLENGE),
SNMP_MIB_ITEM("TCPWinProbe", LINUX_MIB_TCPWINPROBE),
SNMP_MIB_ITEM("TCPKeepAlive", LINUX_MIB_TCPKEEPALIVE),
SNMP_MIB_SENTINEL
};

13
net/ipv4/tcp_output.c
View file

@ -3382,7 +3382,7 @@ EXPORT_SYMBOL_GPL(tcp_send_ack);
* one is with SEG.SEQ=SND.UNA to deliver urgent pointer, another is
* out-of-date with SND.UNA-1 to probe window.
*/
static int tcp_xmit_probe_skb(struct sock *sk, int urgent)
static int tcp_xmit_probe_skb(struct sock *sk, int urgent, int mib)
{
struct tcp_sock *tp = tcp_sk(sk);
struct sk_buff *skb;
@ -3400,6 +3400,7 @@ static int tcp_xmit_probe_skb(struct sock *sk, int urgent)
*/
tcp_init_nondata_skb(skb, tp->snd_una - !urgent, TCPHDR_ACK);
skb_mstamp_get(&skb->skb_mstamp);
NET_INC_STATS_BH(sock_net(sk), mib);
return tcp_transmit_skb(sk, skb, 0, GFP_ATOMIC);
}
@ -3407,12 +3408,12 @@ void tcp_send_window_probe(struct sock *sk)
{
if (sk->sk_state == TCP_ESTABLISHED) {
tcp_sk(sk)->snd_wl1 = tcp_sk(sk)->rcv_nxt - 1;
tcp_xmit_probe_skb(sk, 0);
tcp_xmit_probe_skb(sk, 0, LINUX_MIB_TCPWINPROBE);
}
}
/* Initiate keepalive or window probe from timer. */
int tcp_write_wakeup(struct sock *sk)
int tcp_write_wakeup(struct sock *sk, int mib)
{
struct tcp_sock *tp = tcp_sk(sk);
struct sk_buff *skb;
@ -3449,8 +3450,8 @@ int tcp_write_wakeup(struct sock *sk)
return err;
} else {
if (between(tp->snd_up, tp->snd_una + 1, tp->snd_una + 0xFFFF))
tcp_xmit_probe_skb(sk, 1);
return tcp_xmit_probe_skb(sk, 0);
tcp_xmit_probe_skb(sk, 1, mib);
return tcp_xmit_probe_skb(sk, 0, mib);
}
}
@ -3464,7 +3465,7 @@ void tcp_send_probe0(struct sock *sk)
unsigned long probe_max;
int err;
err = tcp_write_wakeup(sk);
err = tcp_write_wakeup(sk, LINUX_MIB_TCPWINPROBE);
if (tp->packets_out || !tcp_send_head(sk)) {
/* Cancel probe timer, if it is not required. */

2
net/ipv4/tcp_timer.c
View file

@ -616,7 +616,7 @@ static void tcp_keepalive_timer (unsigned long data)
tcp_write_err(sk);
goto out;
}
if (tcp_write_wakeup(sk) <= 0) {
if (tcp_write_wakeup(sk, LINUX_MIB_TCPKEEPALIVE) <= 0) {
icsk->icsk_probes_out++;
elapsed = keepalive_intvl_when(tp);
} else {