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authorFlorian Westphal <fw@strlen.de>2014-02-25 14:34:32 +0100
committerDavid S. Miller <davem@davemloft.net>2014-02-26 15:23:30 -0500
commit8e165e20348b53583f6c6cb45865b89209f4aa13 (patch)
tree26eab521fe1c2ac3aca539d832d747f2c42bc930 /net/ipv4
parent2ebe21fdde1c92ef1654f23d29194145be0e1ddc (diff)
downloadlinux-8e165e20348b53583f6c6cb45865b89209f4aa13.tar.bz2
net: tcp: add mib counters to track zero window transitions
Three counters are added: - one to track when we went from non-zero to zero window - one to track the reverse - one counter incremented when we want to announce zero window, but can't because we would shrink current window. Suggested-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Florian Westphal <fw@strlen.de> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/proc.c3
-rw-r--r--net/ipv4/tcp_output.c12
2 files changed, 14 insertions, 1 deletions
diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
index a6c8a80ec9d6..99d2e9b6fac9 100644
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -280,6 +280,9 @@ static const struct snmp_mib snmp4_net_list[] = {
SNMP_MIB_ITEM("TCPSpuriousRtxHostQueues", LINUX_MIB_TCPSPURIOUS_RTX_HOSTQUEUES),
SNMP_MIB_ITEM("BusyPollRxPackets", LINUX_MIB_BUSYPOLLRXPACKETS),
SNMP_MIB_ITEM("TCPAutoCorking", LINUX_MIB_TCPAUTOCORKING),
+ SNMP_MIB_ITEM("TCPFromZeroWindowAdv", LINUX_MIB_TCPFROMZEROWINDOWADV),
+ SNMP_MIB_ITEM("TCPToZeroWindowAdv", LINUX_MIB_TCPTOZEROWINDOWADV),
+ SNMP_MIB_ITEM("TCPWantZeroWindowAdv", LINUX_MIB_TCPWANTZEROWINDOWADV),
SNMP_MIB_SENTINEL
};
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 21e8a9f33287..c5eadec001c1 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -269,6 +269,7 @@ EXPORT_SYMBOL(tcp_select_initial_window);
static u16 tcp_select_window(struct sock *sk)
{
struct tcp_sock *tp = tcp_sk(sk);
+ u32 old_win = tp->rcv_wnd;
u32 cur_win = tcp_receive_window(tp);
u32 new_win = __tcp_select_window(sk);
@@ -281,6 +282,9 @@ static u16 tcp_select_window(struct sock *sk)
*
* Relax Will Robinson.
*/
+ if (new_win == 0)
+ NET_INC_STATS(sock_net(sk),
+ LINUX_MIB_TCPWANTZEROWINDOWADV);
new_win = ALIGN(cur_win, 1 << tp->rx_opt.rcv_wscale);
}
tp->rcv_wnd = new_win;
@@ -298,8 +302,14 @@ static u16 tcp_select_window(struct sock *sk)
new_win >>= tp->rx_opt.rcv_wscale;
/* If we advertise zero window, disable fast path. */
- if (new_win == 0)
+ if (new_win == 0) {
tp->pred_flags = 0;
+ if (old_win)
+ NET_INC_STATS(sock_net(sk),
+ LINUX_MIB_TCPTOZEROWINDOWADV);
+ } else if (old_win == 0) {
+ NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPFROMZEROWINDOWADV);
+ }
return new_win;
}