sctp: Bring SCTP_DELAYED_ACK socket option into API compliance

Brings delayed_ack socket option set/get into line with the latest ietf
socket extensions API draft, while maintaining backwards compatibility.

Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 21 insertions, 7 deletions

diff --git a/include/net/sctp/user.h b/include/net/sctp/user.h
index 9619b9d35c9e..31371d2553e8 100644
--- a/include/net/sctp/user.h
+++ b/include/net/sctp/user.h
@@ -93,8 +93,9 @@ enum sctp_optname {
 #define SCTP_STATUS SCTP_STATUS
         SCTP_GET_PEER_ADDR_INFO,
 #define SCTP_GET_PEER_ADDR_INFO SCTP_GET_PEER_ADDR_INFO
-        SCTP_DELAYED_ACK_TIME,
-#define SCTP_DELAYED_ACK_TIME SCTP_DELAYED_ACK_TIME
+        SCTP_DELAYED_ACK,
+#define SCTP_DELAYED_ACK_TIME SCTP_DELAYED_ACK
+#define SCTP_DELAYED_ACK SCTP_DELAYED_ACK
         SCTP_CONTEXT,   /* Receive Context */
 #define SCTP_CONTEXT SCTP_CONTEXT
         SCTP_FRAGMENT_INTERLEAVE,
@@ -618,13 +619,26 @@ struct sctp_authkeyid {
 };
 
 
-/* 7.1.23. Delayed Ack Timer (SCTP_DELAYED_ACK_TIME)
+/*
+ * 7.1.23.  Get or set delayed ack timer (SCTP_DELAYED_SACK)
  *
- *   This options will get or set the delayed ack timer.  The time is set
- *   in milliseconds.  If the assoc_id is 0, then this sets or gets the
- *   endpoints default delayed ack timer value.  If the assoc_id field is
- *   non-zero, then the set or get effects the specified association.
+ * This option will effect the way delayed acks are performed.  This
+ * option allows you to get or set the delayed ack time, in
+ * milliseconds.  It also allows changing the delayed ack frequency.
+ * Changing the frequency to 1 disables the delayed sack algorithm.  If
+ * the assoc_id is 0, then this sets or gets the endpoints default
+ * values.  If the assoc_id field is non-zero, then the set or get
+ * effects the specified association for the one to many model (the
+ * assoc_id field is ignored by the one to one model).  Note that if
+ * sack_delay or sack_freq are 0 when setting this option, then the
+ * current values will remain unchanged.
  */
+struct sctp_sack_info {
+        sctp_assoc_t    sack_assoc_id;
+        uint32_t        sack_delay;
+        uint32_t        sack_freq;
+};
+
 struct sctp_assoc_value {
     sctp_assoc_t            assoc_id;
     uint32_t                assoc_value;