Change in osmo-sgsn[master]: Treat RAU as implicit RESUME if GMM is suspended

[laforge]

laforge has uploaded this change for review. ( https://gerrit.osmocom.org/c/osmo-sgsn/+/18877 )


Change subject: Treat RAU as implicit RESUME if GMM is suspended
......................................................................

Treat RAU as implicit RESUME if GMM is suspended

We so far only resumed from suspend upon receiving an explicit BSSGP
RESUME message from the BSS.  The latter is only possible in
BSC-colocated PCU, where the BSC can trigger the message when releasing
the dedicated channel.  In BTS-colocated PCUs, this is not possible,
and we have to rely on the MS resuming by RAU.

See 3GPP TS 23.060 section 16.2.1.1.1 clause 6:

The MS shall resume GPRS services by sending a Routeing Area Update Request message to the SGSN:
* if the BSS did not successfully request the SGSN to resume GPRS services,
* if the RR Channel Release message was not received before the MS left dedicated mode,
* if the MS locally determines that the conditions for the GPRS suspension have disappeared

Without this patch, the GMM state would forever be stuck in SUSPEND,
which in turn causes the SGSN to page the MS all the time.

Change-Id: I3c09187a27483d95fa0070bbb467f94a2ea3978f
Related: OS4616
---
M src/sgsn/gprs_gmm_fsm.c
1 file changed, 4 insertions(+), 2 deletions(-)



  git pull ssh://gerrit.osmocom.org:29418/osmo-sgsn refs/changes/77/18877/1

diff --git a/src/sgsn/gprs_gmm_fsm.c b/src/sgsn/gprs_gmm_fsm.c
index 37ea904..cf1f4c5 100644
--- a/src/sgsn/gprs_gmm_fsm.c
+++ b/src/sgsn/gprs_gmm_fsm.c
@@ -69,7 +69,8 @@
 static void st_gmm_registered_suspended(struct osmo_fsm_inst *fi, uint32_t event, void *data)
 {
 	switch(event) {
-	case E_GMM_RESUME:
+	case E_GMM_RESUME:		/* explicit BSSGP RESUME from BSS */
+	case E_GMM_ATTACH_SUCCESS:	/* implicit resume from MS */
 		gmm_fsm_state_chg(fi, ST_GMM_REGISTERED_NORMAL);
 		break;
 	}
@@ -123,7 +124,8 @@
 		.action = st_gmm_registered_normal,
 	},
 	[ST_GMM_REGISTERED_SUSPENDED] = {
-		.in_event_mask = X(E_GMM_RESUME),
+		.in_event_mask = X(E_GMM_RESUME) |
+				 X(E_GMM_ATTACH_SUCCESS),
 		.out_state_mask =
 			X(ST_GMM_DEREGISTERED) |
 			X(ST_GMM_REGISTERED_NORMAL),

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Gerrit-Project: osmo-sgsn
Gerrit-Branch: master
Gerrit-Change-Id: I3c09187a27483d95fa0070bbb467f94a2ea3978f
Gerrit-Change-Number: 18877
Gerrit-PatchSet: 1
Gerrit-Owner: laforge <laforge at osmocom.org>
Gerrit-MessageType: newchange
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