[MERGED] libosmocore[master]: lapdm: don't enforce contention resolution on SAPI0/DCCH

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Harald Welte gerrit-no-reply at lists.osmocom.org
Wed May 9 14:52:25 UTC 2018


Harald Welte has submitted this change and it was merged.

Change subject: lapdm: don't enforce contention resolution on SAPI0/DCCH
......................................................................


lapdm: don't enforce contention resolution on SAPI0/DCCH

In Change-Id: I8c2c103cdc7f9a45d7b2080c572f559fc3db58e4 we introduced
a check to enforce contention resolution always being used in
MS-originated LAPDm establishment on the main DCCH / SAPI0.  This is
only required after RACH request (IMM.ASS.) and not after a normal
assignment command which was sent already via a dedicated channel.

Hence, we cannot enforce a strict requirement for contention resolution
in those cases.

We *could* use the RSL Channel Activation type as a constraint on
whether or not to enforce contention-resoluiton-only LAPDm
establishment, but this is out of the scope of the LAPDm code but would
have to be done inside OsmoBTS.

Related: OS#3252
Change-Id: Id903492ee90809fe98defcf4abc0419b8150069f
---
M src/gsm/lapdm.c
1 file changed, 2 insertions(+), 5 deletions(-)

Approvals:
  Harald Welte: Looks good to me, approved
  Jenkins Builder: Verified



diff --git a/src/gsm/lapdm.c b/src/gsm/lapdm.c
index b9e7304..3a6fc5b 100644
--- a/src/gsm/lapdm.c
+++ b/src/gsm/lapdm.c
@@ -552,16 +552,13 @@
 				return RLL_CAUSE_SABM_INFO_NOTALL;
 		} else {
 			switch (lctx->sapi) {
-			case 0:
-				/* SAPI0 must use contention resolution, i.e. L3 payload must exist */
-				if (lctx->length == 0)
-					return RLL_CAUSE_UFRM_INC_PARAM;
-				break;
 			case 3:
 				/* SAPI3 doesn't support contention resolution */
 				if (lctx->length > 0)
 					return RLL_CAUSE_SABM_INFO_NOTALL;
 				break;
+			default:
+				break;
 			}
 		}
 	} else if (le->mode == LAPDM_MODE_MS) {

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Gerrit-MessageType: merged
Gerrit-Change-Id: Id903492ee90809fe98defcf4abc0419b8150069f
Gerrit-PatchSet: 1
Gerrit-Project: libosmocore
Gerrit-Branch: master
Gerrit-Owner: Harald Welte <laforge at gnumonks.org>
Gerrit-Reviewer: Harald Welte <laforge at gnumonks.org>
Gerrit-Reviewer: Jenkins Builder



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