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, 28 insertions, 0 deletions

diff --git a/net/sctp/ulpevent.c b/net/sctp/ulpevent.c
index 62d4a7b..c962c60 100644
--- a/net/sctp/ulpevent.c
+++ b/net/sctp/ulpevent.c
@@ -862,6 +862,34 @@ fail:
 	return NULL;
 }
 
+/*
+ * Socket Extensions for SCTP
+ * 6.3.10. SCTP_SENDER_DRY_EVENT
+ */
+struct sctp_ulpevent *sctp_ulpevent_make_sender_dry_event(
+	const struct sctp_association *asoc, gfp_t gfp)
+{
+	struct sctp_ulpevent *event;
+	struct sctp_sender_dry_event *sdry;
+	struct sk_buff *skb;
+
+	event = sctp_ulpevent_new(sizeof(struct sctp_sender_dry_event),
+				  MSG_NOTIFICATION, gfp);
+	if (!event)
+		return NULL;
+
+	skb = sctp_event2skb(event);
+	sdry = (struct sctp_sender_dry_event *)
+		skb_put(skb, sizeof(struct sctp_sender_dry_event));
+
+	sdry->sender_dry_type = SCTP_SENDER_DRY_EVENT;
+	sdry->sender_dry_flags = 0;
+	sdry->sender_dry_length = sizeof(struct sctp_sender_dry_event);
+	sctp_ulpevent_set_owner(event, asoc);
+	sdry->sender_dry_assoc_id = sctp_assoc2id(asoc);
+
+	return event;
+}
 
 /* Return the notification type, assuming this is a notification
  * event.