RSL: keep track if a channel is active or not
This allows us to block packets that we have received after the channel
is no longer being used. This is visible during handover, where we still
receive a measurement report after the MS has switched to the new channel.
This leftover measurement report then attempts to trigger another handover,
which si bogus and will fail - and thus only consumes resources.
With the new LCHAN_S_ACTIVE state, we can check for this when processing
the measurement report.
diff --git a/openbsc/include/openbsc/gsm_data.h b/openbsc/include/openbsc/gsm_data.h
index f3ec9eb..d19f38b 100644
--- a/openbsc/include/openbsc/gsm_data.h
+++ b/openbsc/include/openbsc/gsm_data.h
@@ -151,6 +151,13 @@
#define LCHAN_SAPI_MS 1
#define LCHAN_SAPI_NET 2
+/* state of a logical channel */
+enum gsm_lchan_state {
+ LCHAN_S_NONE, /* channel is not active */
+ LCHAN_S_ACTIVE, /* channel is active and operational */
+ LCHAN_S_INACTIVE, /* channel is set inactive */
+};
+
struct gsm_lchan {
/* The TS that we're part of */
struct gsm_bts_trx_ts *ts;
@@ -162,6 +169,8 @@
enum rsl_cmod_spd rsl_cmode;
/* If TCH, traffic channel mode */
enum gsm48_chan_mode tch_mode;
+ /* State */
+ enum gsm_lchan_state state;
/* Power levels for MS and BTS */
u_int8_t bs_power;
u_int8_t ms_power;
diff --git a/openbsc/src/abis_rsl.c b/openbsc/src/abis_rsl.c
index a50d7aa..72ae9db 100644
--- a/openbsc/src/abis_rsl.c
+++ b/openbsc/src/abis_rsl.c
@@ -918,6 +918,8 @@
if (rslh->ie_chan != RSL_IE_CHAN_NR)
return -EINVAL;
+ msg->lchan->state = LCHAN_S_ACTIVE;
+
dispatch_signal(SS_LCHAN, S_LCHAN_ACTIVATE_ACK, msg->lchan);
return 0;
@@ -938,6 +940,8 @@
print_rsl_cause(TLVP_VAL(&tp, RSL_IE_CAUSE),
TLVP_LEN(&tp, RSL_IE_CAUSE));
+ msg->lchan->state = LCHAN_S_NONE;
+
dispatch_signal(SS_LCHAN, S_LCHAN_ACTIVATE_NACK, msg->lchan);
lchan_free(msg->lchan);
@@ -1022,6 +1026,11 @@
const u_int8_t *val;
int rc;
+ /* check if this channel is actually active */
+ /* FIXME: maybe this check should be way more generic/centralized */
+ if (msg->lchan->state != LCHAN_S_ACTIVE)
+ return 0;
+
memset(mr, 0, sizeof(*mr));
mr->lchan = msg->lchan;
@@ -1128,6 +1137,7 @@
break;
case RSL_MT_RF_CHAN_REL_ACK:
DEBUGPC(DRSL, "RF CHANNEL RELEASE ACK\n");
+ msg->lchan->state = LCHAN_S_NONE;
lchan_free(msg->lchan);
break;
case RSL_MT_MODE_MODIFY_ACK: