[SCTP]: Set assoc_id correctly during INIT collision.

During the INIT/COOKIE-ACK collision cases, it's possible to get
into a situation where the association id is not yet set at the time
of the user event generation.  As a result, user events have an
association id set to 0 which will confuse applications.

This happens if we hit case B of duplicate cookie processing.
In the particular example found and provided by Oscar Isaula
<Oscar.Isaula@motorola.com>, flow looks like this:
A				B
---- INIT------->  (lost)
	    <---------INIT------
---- INIT-ACK--->
	    <------ Cookie ECHO

When the Cookie Echo is received, we end up trying to update the
association that was created on A as a result of the (lost) INIT,
but that association doesn't have the ID set yet.

Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index 7b4fff9..5e81984 100644
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -1857,6 +1857,7 @@
 int sctp_assoc_set_bind_addr_from_cookie(struct sctp_association *,
 					 struct sctp_cookie*,
 					 gfp_t gfp);
+int sctp_assoc_set_id(struct sctp_association *, gfp_t);
 
 int sctp_cmp_addr_exact(const union sctp_addr *ss1,
 			const union sctp_addr *ss2);