dccp: Return-value convention of hc_tx_send_packet()

This patch reorganises the return value convention of the CCID TX sending
function, to permit more flexible schemes, as required by subsequent patches.

Currently the convention is
 * values < 0     mean error,
 * a value == 0   means "send now", and
 * a value x > 0  means "send in x milliseconds".

The patch provides symbolic constants and a function to interpret return values.

In addition, it caps the maximum positive return value to 0xFFFF milliseconds,
corresponding to 65.535 seconds.  This is possible since in CCID-3/4 the
maximum possible inter-packet gap is fixed at t_mbi = 64 sec.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 6 deletions

diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c
index 3060a60ed5ab..3d604e1349c0 100644
--- a/net/dccp/ccids/ccid3.c
+++ b/net/dccp/ccids/ccid3.c
@@ -268,11 +268,11 @@ out:
         sock_put(sk);
 }
 
-/*
- * returns
- *   > 0: delay (in msecs) that should pass before actually sending
- *   = 0: can send immediately
- *   < 0: error condition; do not send packet
+/**
+ * ccid3_hc_tx_send_packet  -  Delay-based dequeueing of TX packets
+ * @skb: next packet candidate to send on @sk
+ * This function uses the convention of ccid_packet_dequeue_eval() and
+ * returns a millisecond-delay value between 0 and t_mbi = 64000 msec.
  */
 static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb)
 {
@@ -348,7 +348,7 @@ static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb)
 
         /* set the nominal send time for the next following packet */
         hc->tx_t_nom = ktime_add_us(hc->tx_t_nom, hc->tx_t_ipi);
-        return 0;
+        return CCID_PACKET_SEND_AT_ONCE;
 }
 
 static void ccid3_hc_tx_packet_sent(struct sock *sk, unsigned int len)