sctp: implement the receiver side for SACK-IMMEDIATELY extension

This patch implement the receiver side for SACK-IMMEDIATELY
extension:

  Section 4.2.  Receiver Side Considerations

  On reception of an SCTP packet containing a DATA chunk with the I-bit
  set, the receiver SHOULD NOT delay the sending of the corresponding
  SACK chunk and SHOULD send it back immediately.

Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
index d4df45022ffa..8ee24c9dc7e9 100644
--- a/net/sctp/sm_statefuns.c
+++ b/net/sctp/sm_statefuns.c
@@ -2868,6 +2868,7 @@ sctp_disposition_t sctp_sf_eat_data_6_2(const struct sctp_endpoint *ep,
                                         sctp_cmd_seq_t *commands)
 {
         struct sctp_chunk *chunk = arg;
+        sctp_arg_t force = SCTP_NOFORCE();
         int error;
 
         if (!sctp_vtag_verify(chunk, asoc)) {
@@ -2901,6 +2902,9 @@ sctp_disposition_t sctp_sf_eat_data_6_2(const struct sctp_endpoint *ep,
                 BUG();
         }
 
+        if (chunk->chunk_hdr->flags & SCTP_DATA_SACK_IMM)
+                force = SCTP_FORCE();
+
         if (asoc->autoclose) {
                 sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART,
                                 SCTP_TO(SCTP_EVENT_TIMEOUT_AUTOCLOSE));
@@ -2929,7 +2933,7 @@ sctp_disposition_t sctp_sf_eat_data_6_2(const struct sctp_endpoint *ep,
          * more aggressive than the following algorithms allow.
          */
         if (chunk->end_of_packet)
-                sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SACK, SCTP_NOFORCE());
+                sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SACK, force);
 
         return SCTP_DISPOSITION_CONSUME;
 
@@ -2954,7 +2958,7 @@ discard_force:
 
 discard_noforce:
         if (chunk->end_of_packet)
-                sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SACK, SCTP_NOFORCE());
+                sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SACK, force);
 
         return SCTP_DISPOSITION_DISCARD;
 consume: