lchan: Release the lchan more quickly, align with GSM 04.08

* Release all channels with SAPI > 0 with the "local end release"
  (as of NOTE 1 of GSM 04.08).
* No need to wait for all SAPIs to be torn down and the normal
  REL_IND/REL_CONF will call rsl_handle_release and the channel
  should be released.
* Update the documentation

1 files changed, 14 insertions, 47 deletions

diff --git a/openbsc/src/libbsc/chan_alloc.c b/openbsc/src/libbsc/chan_alloc.c
index 1efe2aac3..a8b15d177 100644
--- a/openbsc/src/libbsc/chan_alloc.c
+++ b/openbsc/src/libbsc/chan_alloc.c
@@ -345,8 +345,6 @@ void lchan_free(struct gsm_lchan *lchan)
 	}
 
 	lchan->sacch_deact = 0;
-	lchan->release_mode = RSL_REL_NORMAL;
-
 	/* FIXME: ts_free() the timeslot, if we're the last logical
 	 * channel using it */
 }
@@ -376,51 +374,22 @@ void lchan_reset(struct gsm_lchan *lchan)
 	}
 }
 
-/* release the next allocated SAPI or return 0 */
-static int _lchan_release_next_sapi(struct gsm_lchan *lchan)
-{
-	int sapi;
-
-	for (sapi = 1; sapi < ARRAY_SIZE(lchan->sapis); ++sapi) {
-		uint8_t link_id;
-		if (lchan->sapis[sapi] == LCHAN_SAPI_UNUSED)
-			continue;
-
-		link_id = sapi;
-		if (lchan->type == GSM_LCHAN_TCH_F || lchan->type == GSM_LCHAN_TCH_H)
-			link_id |= 0x40;
-		rsl_release_request(lchan, link_id, RSL_REL_LOCAL_END);
-		return 0;
-	}
-
-	return 1;
-}
-
 /* Drive the release process of the lchan */
-static void _lchan_handle_release(struct gsm_lchan *lchan)
+static void _lchan_handle_release(struct gsm_lchan *lchan,
+				  int sach_deact, int mode)
 {
-	/* Ask for SAPI != 0 to be freed first and stop if we need to wait */
-	if (_lchan_release_next_sapi(lchan) == 0)
-		return;
-
-	if (lchan->sacch_deact) {
+	/* Release all SAPIs on the local end and continue */
+	rsl_release_sapis_from(lchan, 1, RSL_REL_LOCAL_END);
+
+	/*
+	 * Shall we send a RR Release, start T3109 and wait for the
+	 * release indication from the BTS or just take it down (e.g.
+	 * on assignment requests)
+	 */
+	if (sach_deact)
 		gsm48_send_rr_release(lchan);
-		return;
-	}
-
-	rsl_release_request(lchan, 0, lchan->release_mode);
-	rsl_lchan_set_state(lchan, LCHAN_S_REL_REQ);
-}
-
-/* called from abis rsl */
-int rsl_lchan_rll_release(struct gsm_lchan *lchan, uint8_t link_id)
-{
-	if (lchan->state != LCHAN_S_REL_REQ)
-		return -1;
-
-	if ((link_id & 0x7) != 0)
-		_lchan_handle_release(lchan);
-	return 0;
+	else
+		rsl_release_request(lchan, 0, mode);
 }
 
 /* Consider releasing the channel now */
@@ -430,9 +399,7 @@ int lchan_release(struct gsm_lchan *lchan, int sacch_deact, enum rsl_rel_mode mo
 	rsl_lchan_set_state(lchan, LCHAN_S_REL_REQ);
 
 	lchan->conn = NULL;
-	lchan->release_mode = mode;
-	lchan->sacch_deact = sacch_deact;
-	_lchan_handle_release(lchan);
+	_lchan_handle_release(lchan, sacch_deact, mode);
 	return 1;
 }