[TCP]: MTU probing
Implementation of packetization layer path mtu discovery for TCP, based on
the internet-draft currently found at
<http://www.ietf.org/internet-drafts/draft-ietf-pmtud-method-05.txt>.
Signed-off-by: John Heffner <jheffner@psc.edu>
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 fa587c9..b3abe33 100644
--- a/include/net/inet_connection_sock.h
+++ b/include/net/inet_connection_sock.h
@@ -72,6 +72,7 @@
* @icsk_probes_out: unanswered 0 window probes
* @icsk_ext_hdr_len: Network protocol overhead (IP/IPv6 options)
* @icsk_ack: Delayed ACK control data
+ * @icsk_mtup; MTU probing control data
*/
struct inet_connection_sock {
/* inet_sock has to be the first member! */
@@ -104,6 +105,18 @@
__u16 last_seg_size; /* Size of last incoming segment */
__u16 rcv_mss; /* MSS used for delayed ACK decisions */
} icsk_ack;
+ struct {
+ int enabled;
+
+ /* Range of MTUs to search */
+ int search_high;
+ int search_low;
+
+ /* Information on the current probe. */
+ int probe_size;
+ __u32 probe_seq_start;
+ __u32 probe_seq_end;
+ } icsk_mtup;
u32 icsk_ca_priv[16];
#define ICSK_CA_PRIV_SIZE (16 * sizeof(u32))
};
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 77f21c6..16879fa 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -60,6 +60,9 @@
/* Minimal RCV_MSS. */
#define TCP_MIN_RCVMSS 536U
+/* The least MTU to use for probing */
+#define TCP_BASE_MSS 512
+
/* After receiving this amount of duplicate ACKs fast retransmit starts. */
#define TCP_FASTRETRANS_THRESH 3
@@ -219,6 +222,8 @@
extern int sysctl_tcp_moderate_rcvbuf;
extern int sysctl_tcp_tso_win_divisor;
extern int sysctl_tcp_abc;
+extern int sysctl_tcp_mtu_probing;
+extern int sysctl_tcp_base_mss;
extern atomic_t tcp_memory_allocated;
extern atomic_t tcp_sockets_allocated;
@@ -447,6 +452,10 @@
extern void tcp_initialize_rcv_mss(struct sock *sk);
+extern int tcp_mtu_to_mss(struct sock *sk, int pmtu);
+extern int tcp_mss_to_mtu(struct sock *sk, int mss);
+extern void tcp_mtup_init(struct sock *sk);
+
static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
{
tp->pred_flags = htonl((tp->tcp_header_len << 26) |