bts_trx: Drop non-executed path in trx_link_estab()

This function is only called during sign_link_up() e1inp callback, hence
only the link!=NULL condition (UP) is ever executed. Let's drop the DOWN
path and make it a function only used to trigger events when link
becomes up, similar to what bts_link_estab() does with OML.

Here it becomes clear the NM_EV_RSL_DOWN was never sent. It's not much
of an issue though since it would only make transition RCARRIER/BBTRANSC
Enabled->DisabledOffline. However, since due to libosmo-abis limitation
we receive a sign_link_down() for the entire line when 1 of its links
goes down, we don't care much since we go for shutdown of the entire BTS
anyway. Ideally, libosmo-abis would support simply telling us 1 of the
links in the line went down and if it was not OML and not RSL TRX==C0,
then we could keep on running and simply disable the related TRX.

Change-Id: Iac553c68339c0da32fd313676995747eb4344087

1 files changed, 8 insertions, 0 deletions

diff --git a/src/common/abis.c b/src/common/abis.c
index 1722f3de..1b489c17 100644
--- a/src/common/abis.c
+++ b/src/common/abis.c
@@ -214,6 +214,14 @@ static void abis_link_connected(struct osmo_fsm_inst *fi, uint32_t event, void *
 			e1inp_sign_link_destroy(trx->rsl_link);
 			trx->rsl_link = NULL;
 		}
+		/* Note: Here we could send NM_EV_RSL_DOWN to each
+		 * trx->(bb_transc.)mo.fi, but we are starting shutdown of the
+		 * entire BTS anyway through bts_model_abis_close(), so simply
+		 * let bts_shutdown FSM take care of slowly powering down all
+		 * the TRX. It would make sense to send NM_EV_RSL_DOWN only if a
+		 * RSL link TRX!=C0 was going down, in order to selectively stop
+		 * that TRX only. But libosmo-abis expects us to drop the entire
+		 * line when something goes wrong... */
 	}
 	bts_model_abis_close(bts);
 	osmo_fsm_inst_state_chg(fi, ABIS_LINK_ST_WAIT_RECONNECT, OML_RETRY_TIMER, 0);