Harald Welte has submitted this change and it was merged.

Change subject: bsc_api/GSCON: prevent unnecessary channel mode modifications
......................................................................


bsc_api/GSCON: prevent unnecessary channel mode modifications

gsm0808_assign_req() checks if the new channel mode is compatible
with the new mode. If it is, it does a gsm48_lchan_modify(), but
it does not actually check if the new mode is equal to the current
mode.

- skip when the channel is compatible and the new mode is equal to
  the old mode.

- send the ASSIGNMENT COMPLETE directly from ST_ACTIVE when no
  mode modify was necessary.

Change-Id: I86a2d52836c54d2dbd77441b182f757327ec7262
Related: OS#2936
---
M src/libbsc/bsc_api.c
M src/libbsc/bsc_subscr_conn_fsm.c
2 files changed, 19 insertions(+), 9 deletions(-)

Approvals:
  Harald Welte: Looks good to me, approved
  Jenkins Builder: Verified



diff --git a/src/libbsc/bsc_api.c b/src/libbsc/bsc_api.c
index 142efef..19859cf 100644
--- a/src/libbsc/bsc_api.c
+++ b/src/libbsc/bsc_api.c
@@ -296,16 +296,17 @@
        }
 }
 
-/**
- * Send a GSM08.08 Assignment Request. Right now this does not contain the
- * audio codec type or the allowed rates for the config. It is assumed that
- * this is for audio handling only. In case the current channel does not allow
- * the selected mode a new one will be allocated.
- *
- * TODO: Add multirate configuration, make it work for more than audio.
- */
+/*! Send a GSM08.08 Assignment Request. Right now this does not contain the
+ *  audio codec type or the allowed rates for the config. In case the current
+ *  channel does not allow the selected mode a new one will be allocated.
+ *  \param[out] conn related subscriber connection
+ *  \param[in] chan_mode mode of the channel (see enum gsm48_chan_mode)
+ *  \param[in] full_rate select full rate or half rate channel
+ *  \returns 0 on success, 1 when no operation is neccessary, -1 on failure */
 int gsm0808_assign_req(struct gsm_subscriber_connection *conn, int chan_mode, 
int full_rate)
 {
+       /* TODO: Add multirate configuration, make it work for more than audio. 
*/
+
        struct bsc_api *api;
        api = conn->network->bsc_api;
 
@@ -313,6 +314,11 @@
                if (handle_new_assignment(conn, chan_mode, full_rate) != 0)
                        goto error;
        } else {
+               /* Check if the channel is already in the requested mode, if
+                * yes, we skip unnecessary channel mode modify operations. */
+               if (conn->lchan->tch_mode == chan_mode)
+                       return 1;
+
                if (chan_mode == GSM48_CMODE_SPEECH_AMR)
                        handle_mr_config(conn, conn->lchan, full_rate);
 
diff --git a/src/libbsc/bsc_subscr_conn_fsm.c b/src/libbsc/bsc_subscr_conn_fsm.c
index b5e7e7d..7f53f1b 100644
--- a/src/libbsc/bsc_subscr_conn_fsm.c
+++ b/src/libbsc/bsc_subscr_conn_fsm.c
@@ -438,7 +438,11 @@
                         * change back to ST_ACTIVE (here) immediately. */
                        rc = gsm0808_assign_req(conn, 
conn->user_plane.chan_mode,
                                                conn->user_plane.full_rate);
-                       if (rc != 0) {
+
+                       if (rc == 1) {
+                               send_ass_compl(conn->lchan, fi, false);
+                               return;
+                       } else if (rc != 0) {
                                resp = 
gsm0808_create_assignment_failure(GSM0808_CAUSE_EQUIPMENT_FAILURE, NULL);
                                sigtran_send(conn, resp, fi);
                                return;

-- 
To view, visit https://gerrit.osmocom.org/8019
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Gerrit-MessageType: merged
Gerrit-Change-Id: I86a2d52836c54d2dbd77441b182f757327ec7262
Gerrit-PatchSet: 3
Gerrit-Project: osmo-bsc
Gerrit-Branch: master
Gerrit-Owner: dexter <pma...@sysmocom.de>
Gerrit-Reviewer: Harald Welte <lafo...@gnumonks.org>
Gerrit-Reviewer: Jenkins Builder

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