5 files changed, 27 insertions, 1 deletions

diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h
index dda72bf5b9b4..16baef4dab7e 100644
--- a/include/net/sctp/sctp.h
+++ b/include/net/sctp/sctp.h
@@ -503,6 +503,13 @@ static inline int sctp_frag_point(const struct sctp_sock *sp, int pmtu)
         return frag;
 }
 
+static inline void sctp_assoc_pending_pmtu(struct sctp_association *asoc)
+{
+
+        sctp_assoc_sync_pmtu(asoc);
+        asoc->pmtu_pending = 0;
+}
+
 /* Walk through a list of TLV parameters.  Don't trust the
  * individual parameter lengths and instead depend on
  * the chunk length to indicate when to stop.  Make sure
diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index dc0e70cb0f8b..ee4559b11302 100644
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -912,6 +912,9 @@ struct sctp_transport {
          */
         __u16 pathmaxrxt;
 
+        /* is the Path MTU update pending on this tranport */
+        __u8 pmtu_pending;
+
         /* PMTU       : The current known path MTU.  */
         __u32 pathmtu;
 
@@ -1566,6 +1569,9 @@ struct sctp_association {
          */
         __u16 pathmaxrxt;
 
+        /* Flag that path mtu update is pending */
+        __u8   pmtu_pending;
+
         /* Association : The smallest PMTU discovered for all of the
          * PMTU        : peer's transport addresses.
          */
diff --git a/net/sctp/associola.c b/net/sctp/associola.c
index df94e3cdfba3..498edb0cd4e5 100644
--- a/net/sctp/associola.c
+++ b/net/sctp/associola.c
@@ -1231,6 +1231,10 @@ void sctp_assoc_sync_pmtu(struct sctp_association *asoc)
         /* Get the lowest pmtu of all the transports. */
         list_for_each(pos, &asoc->peer.transport_addr_list) {
                 t = list_entry(pos, struct sctp_transport, transports);
+                if (t->pmtu_pending && t->dst) {
+                        sctp_transport_update_pmtu(t, dst_mtu(t->dst));
+                        t->pmtu_pending = 0;
+                }
                 if (!pmtu || (t->pathmtu < pmtu))
                         pmtu = t->pathmtu;
         }
diff --git a/net/sctp/input.c b/net/sctp/input.c
index 45d6a644cf06..d57ff7f3c576 100644
--- a/net/sctp/input.c
+++ b/net/sctp/input.c
@@ -367,9 +367,15 @@ static void sctp_add_backlog(struct sock *sk, struct sk_buff *skb)
 void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc,
                            struct sctp_transport *t, __u32 pmtu)
 {
-        if (sock_owned_by_user(sk) || !t || (t->pathmtu == pmtu))
+        if (!t || (t->pathmtu == pmtu))
                 return;
 
+        if (sock_owned_by_user(sk)) {
+                asoc->pmtu_pending = 1;
+                t->pmtu_pending = 1;
+                return;
+        }
+
         if (t->param_flags & SPP_PMTUD_ENABLE) {
                 /* Update transports view of the MTU */
                 sctp_transport_update_pmtu(t, pmtu);
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 45510c46c223..6edaaa009d62 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -1662,6 +1662,9 @@ SCTP_STATIC int sctp_sendmsg(struct kiocb *iocb, struct sock *sk,
                 goto out_free;
         }
 
+        if (asoc->pmtu_pending)
+                sctp_assoc_pending_pmtu(asoc);
+
         /* If fragmentation is disabled and the message length exceeds the
          * association fragmentation point, return EMSGSIZE.  The I-D
          * does not specify what this error is, but this looks like