sctp: implement event notification SCTP_SENDER_DRY_EVENT

This patch implement event notification SCTP_SENDER_DRY_EVENT.
SCTP Socket API Extensions:

  6.1.9. SCTP_SENDER_DRY_EVENT

  When the SCTP stack has no more user data to send or retransmit, this
  notification is given to the user. Also, at the time when a user app
  subscribes to this event, if there is no data to be sent or
  retransmit, the stack will immediately send up this notification.

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, 24 insertions, 0 deletions

diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
index 736847e44e7e..7f4a4f8368ee 100644
--- a/net/sctp/sm_statefuns.c
+++ b/net/sctp/sm_statefuns.c
@@ -5077,6 +5077,30 @@ sctp_disposition_t sctp_sf_ignore_primitive(
  ***************************************************************************/
 
 /*
+ * When the SCTP stack has no more user data to send or retransmit, this
+ * notification is given to the user. Also, at the time when a user app
+ * subscribes to this event, if there is no data to be sent or
+ * retransmit, the stack will immediately send up this notification.
+ */
+sctp_disposition_t sctp_sf_do_no_pending_tsn(
+        const struct sctp_endpoint *ep,
+        const struct sctp_association *asoc,
+        const sctp_subtype_t type,
+        void *arg,
+        sctp_cmd_seq_t *commands)
+{
+        struct sctp_ulpevent *event;
+
+        event = sctp_ulpevent_make_sender_dry_event(asoc, GFP_ATOMIC);
+        if (!event)
+                return SCTP_DISPOSITION_NOMEM;
+
+        sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(event));
+
+        return SCTP_DISPOSITION_CONSUME;
+}
+
+/*
  * Start the shutdown negotiation.
  *
  * From Section 9.2: