1 files changed, 23 insertions, 0 deletions

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 6766913a53e6..08c6238802de 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -2073,10 +2073,33 @@ static int sctp_setsockopt_disable_fragments(struct sock *sk,
 static int sctp_setsockopt_events(struct sock *sk, char __user *optval,
                                   unsigned int optlen)
 {
+        struct sctp_association *asoc;
+        struct sctp_ulpevent *event;
+
         if (optlen > sizeof(struct sctp_event_subscribe))
                 return -EINVAL;
         if (copy_from_user(&sctp_sk(sk)->subscribe, optval, optlen))
                 return -EFAULT;
+
+        /*
+         * At the time when a user app subscribes to SCTP_SENDER_DRY_EVENT,
+         * if there is no data to be sent or retransmit, the stack will
+         * immediately send up this notification.
+         */
+        if (sctp_ulpevent_type_enabled(SCTP_SENDER_DRY_EVENT,
+                                       &sctp_sk(sk)->subscribe)) {
+                asoc = sctp_id2assoc(sk, 0);
+
+                if (asoc && sctp_outq_is_empty(&asoc->outqueue)) {
+                        event = sctp_ulpevent_make_sender_dry_event(asoc,
+                                        GFP_ATOMIC);
+                        if (!event)
+                                return -ENOMEM;
+
+                        sctp_ulpq_tail_event(&asoc->ulpq, event);
+                }
+        }
+
         return 0;
 }