rxrpc: Send pings to get RTT data
Send a PING ACK packet to the peer when we get a new incoming call from a
peer we don't have a record for. The PING RESPONSE ACK packet will tell us
the following about the peer:
(1) its receive window size
(2) its MTU sizes
(3) its support for jumbo DATA packets
(4) if it supports slow start (similar to RFC 5681)
(5) an estimate of the RTT
This is necessary because the peer won't normally send us an ACK until it
gets to the Rx phase and we send it a packet, but we would like to know
some of this information before we start sending packets.
A pair of tracepoints are added so that RTT determination can be observed.
Signed-off-by: David Howells <dhowells@redhat.com>
diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index 79c671e..8b47f46 100644
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -403,6 +403,7 @@
RXRPC_CALL_EXPOSED, /* The call was exposed to the world */
RXRPC_CALL_RX_LAST, /* Received the last packet (at rxtx_top) */
RXRPC_CALL_TX_LAST, /* Last packet in Tx buffer (at rxtx_top) */
+ RXRPC_CALL_PINGING, /* Ping in process */
};
/*
@@ -487,6 +488,8 @@
u32 call_id; /* call ID on connection */
u32 cid; /* connection ID plus channel index */
int debug_id; /* debug ID for printks */
+ unsigned short rx_pkt_offset; /* Current recvmsg packet offset */
+ unsigned short rx_pkt_len; /* Current recvmsg packet len */
/* Rx/Tx circular buffer, depending on phase.
*
@@ -530,8 +533,8 @@
u16 ackr_skew; /* skew on packet being ACK'd */
rxrpc_serial_t ackr_serial; /* serial of packet being ACK'd */
rxrpc_seq_t ackr_prev_seq; /* previous sequence number received */
- unsigned short rx_pkt_offset; /* Current recvmsg packet offset */
- unsigned short rx_pkt_len; /* Current recvmsg packet len */
+ rxrpc_serial_t ackr_ping; /* Last ping sent */
+ ktime_t ackr_ping_time; /* Time last ping sent */
/* transmission-phase ACK management */
rxrpc_serial_t acks_latest; /* serial number of latest ACK received */