ipv4: Create probe timer for tcp PMTU as per RFC4821

As per RFC4821 7.3.  Selecting Probe Size, a probe timer should
be armed once probing has converged. Once this timer expired,
probing again to take advantage of any path PMTU change. The
recommended probing interval is 10 minutes per RFC1981. Probing
interval could be sysctled by sysctl_tcp_probe_interval.

Eric Dumazet suggested to implement pseudo timer based on 32bits
jiffies tcp_time_stamp instead of using classic timer for such
rare event.

Signed-off-by: Fan Du <fan.du@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h
index 5976bde..b9a6b0a 100644 (file)
--- a/include/net/inet_connection_sock.h
+++ b/include/net/inet_connection_sock.h
@@ -126,6 +126,8 @@ struct inet_connection_sock {
 
                /* Information on the current probe. */
                int               probe_size;
+
+               u32               probe_timestamp;
        } icsk_mtup;
        u32                       icsk_ca_priv[16];
        u32                       icsk_user_timeout;

diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h
index e051d39..8f3a1a1 100644 (file)
--- a/include/net/netns/ipv4.h
+++ b/include/net/netns/ipv4.h
@@ -88,6 +88,7 @@ struct netns_ipv4 {
        int sysctl_tcp_mtu_probing;
        int sysctl_tcp_base_mss;
        int sysctl_tcp_probe_threshold;
+       u32 sysctl_tcp_probe_interval;
 
        struct ping_group_range ping_group_range;
 

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 1ad82e3..2e11e38 100644 (file)
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -67,6 +67,9 @@ void tcp_time_wait(struct sock *sk, int state, int timeo);
 /* The least MTU to use for probing */
 #define TCP_BASE_MSS           1024
 
+/* probing interval, default to 10 minutes as per RFC4821 */
+#define TCP_PROBE_INTERVAL     600
+
 /* Specify interval when tcp mtu probing will stop */
 #define TCP_PROBE_THRESHOLD    8
 

diff --cc net/ipv4/sysctl_net_ipv4.c
Simple merge

diff --cc net/ipv4/tcp_ipv4.c
Simple merge

diff --cc net/ipv4/tcp_output.c
Simple merge

diff --cc net/ipv4/tcp_timer.c
Simple merge