netdev - [SCTP] Initialization collision problem

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Date:	Wed, 4 Apr 2007 09:35:24 -0500
From:	"Isaula Oscar-QOI000" <Oscar.Isaula@...orola.com>
To:	<netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [SCTP] Initialization collision problem

I ran into a problem where LKSCTP is reporting a SCTM_COMM_UP indication
to the User application but is giving back a value of zero for the
assoc_id.

Attached are the SCTP debugs for the period in question.

A couple of things that I would like to note about my setup. One is that
I'm running Kernel version 2.6.10 (I know is old but I can't move to a
newer version due to custom drivers). The second thing is that the link
between the two SCTP node is a very noisy and some messages are getting
lost (i.e. the INIT_ACK from the peer in this particular case).

After analyzing the SCTP code I came out with the following code
changes:

--- sm_statefuns.c.old  2007-04-04 08:58:34.074606000 -0500
+++ sm_statefuns.c.new  2007-04-04 09:03:31.818426000 -0500
@@ -1515,7 +1515,7 @@
  */
 /* This case represents an initialization collision.  */
 static sctp_disposition_t sctp_sf_do_dupcook_b(const struct
sctp_endpoint *ep,
-                    const struct sctp_association *asoc,
+                    struct sctp_association *asoc,
                     struct sctp_chunk *chunk,
                     sctp_cmd_seq_t *commands,
                     struct sctp_association *new_asoc)
@@ -1528,13 +1528,13 @@
      * side effects--it is safe to run them here.
      */
     peer_init = &chunk->subh.cookie_hdr->c.peer_init[0];
-    if (!sctp_process_init(new_asoc, chunk->chunk_hdr->type,
+    if (!sctp_process_init(asoc, chunk->chunk_hdr->type,
                    sctp_source(chunk), peer_init,
                    GFP_ATOMIC))
         goto nomem;
 
     /* Update the content of current association.  */
-    sctp_add_cmd_sf(commands, SCTP_CMD_UPDATE_ASSOC,
SCTP_ASOC(new_asoc));
+    sctp_add_cmd_sf(commands, SCTP_CMD_UPDATE_ASSOC, SCTP_ASOC(asoc));
     sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
             SCTP_STATE(SCTP_STATE_ESTABLISHED));
     SCTP_INC_STATS(SCTP_MIB_CURRESTAB);
@@ -1554,8 +1554,8 @@
      * upon reception of a valid COOKIE ECHO chunk.
      */
     ev = sctp_ulpevent_make_assoc_change(asoc, 0, SCTP_COMM_UP, 0,
-                         new_asoc->c.sinit_num_ostreams,
-                         new_asoc->c.sinit_max_instreams,
+                         asoc->c.sinit_num_ostreams,
+                         asoc->c.sinit_max_instreams,
                          GFP_ATOMIC);
     if (!ev)
         goto nomem_ev;

-----------------------------------------

I can't say that I'm an expert on this area so I'm hoping someone in the
list can provide some feedback. The change has been tested and it fixes
the original problem and we have not detected any side effects so far.

Thanks,
Oscar





View attachment "initLog.txt" of type "text/plain" (9759 bytes)