sctp: Fix to handle SHUTDOWN in SHUTDOWN_RECEIVED state

Once an endpoint has reached the SHUTDOWN-RECEIVED state,
it MUST NOT send a SHUTDOWN in response to a ULP request.
The Cumulative TSN Ack of the received SHUTDOWN chunk
MUST be processed.

This patch fix to process Cumulative TSN Ack of the received
SHUTDOWN chunk in SHUTDOWN_RECEIVED state.

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>
diff --git a/include/net/sctp/sm.h b/include/net/sctp/sm.h
index 029a54a..c1dd893 100644
--- a/include/net/sctp/sm.h
+++ b/include/net/sctp/sm.h
@@ -125,6 +125,7 @@
 sctp_state_fn_t sctp_sf_backbeat_8_3;
 sctp_state_fn_t sctp_sf_do_9_2_final;
 sctp_state_fn_t sctp_sf_do_9_2_shutdown;
+sctp_state_fn_t sctp_sf_do_9_2_shut_ctsn;
 sctp_state_fn_t sctp_sf_do_ecn_cwr;
 sctp_state_fn_t sctp_sf_do_ecne;
 sctp_state_fn_t sctp_sf_ootb;