sub: Remove the queue from the subscriber code

The idea of "subscriber_get_channel" was that different
requests would be coordinated. At the same time we have
seen that the "queue" can get stuck at both 31C3 and the
rhizomatica installations.

Voice calls and SMS do not need coordination. We should
be able to send SMS on a voice channel and switch the MS
from a SDCCH to a TCH in case we establish a voice call.
The SMS code itself needs to coordinate to obey the limit
of one SMS per direction but this should be enforced in
the sms layer and not on the subscriber.

Modify the code to have a simple paging coordination. The
subscriber code will schedule the paging and register who
would like to know about success/failure.

This allowed to greatly simplify the paging response
handling for the transaction code (and in fact we could
move the transaction list into the subscriber structure
now). The code gained to support to cancel the notification
of a request (but not the paging itself yet).

TODO: Cancel paging request in case no one cares about it
anymore.

1 files changed, 7 insertions, 1 deletions

diff --git a/openbsc/src/libmsc/gsm_04_11.c b/openbsc/src/libmsc/gsm_04_11.c
index bcc25e4c2..1b2a42c4f 100644
--- a/openbsc/src/libmsc/gsm_04_11.c
+++ b/openbsc/src/libmsc/gsm_04_11.c
@@ -938,6 +938,7 @@ int gsm411_send_sms_subscr(struct gsm_subscriber *subscr,
 			   struct gsm_sms *sms)
 {
 	struct gsm_subscriber_connection *conn;
+	void *res;
 
 	/* check if we already have an open lchan to the subscriber.
 	 * if yes, send the SMS this way */
@@ -947,7 +948,12 @@ int gsm411_send_sms_subscr(struct gsm_subscriber *subscr,
 	}
 
 	/* if not, we have to start paging */
-	subscr_get_channel(subscr, RSL_CHANNEED_SDCCH, paging_cb_send_sms, sms);
+	res = subscr_request_channel(subscr, RSL_CHANNEED_SDCCH,
+					paging_cb_send_sms, sms);
+	if (!res) {
+		send_signal(S_SMS_UNKNOWN_ERROR, NULL, sms, GSM_PAGING_BUSY);
+		sms_free(sms);
+	}
 	return 0;
 }