LAPDm: Add an extra queue for UI frames
The extra queue is used to transmit the UI frame only when there is no
frame in the regular TX queue. This allows to give LAPD frames prioity
over UI frame.
Related: OS#4074
Change-Id: I00c8ee73be8b7c564a4dee3fca3e893484f567da
diff --git a/src/gsm/lapdm.c b/src/gsm/lapdm.c
index d609317..28644c2 100644
--- a/src/gsm/lapdm.c
+++ b/src/gsm/lapdm.c
@@ -200,6 +200,7 @@
lapdm_dl_init(&le->datalink[i], le, (t200_ms) ? t200_ms[i] : 0, n200, name);
} else
lapdm_dl_init(&le->datalink[i], le, (t200_ms) ? t200_ms[i] : 0, n200, NULL);
+ INIT_LLIST_HEAD(&le->datalink[i].tx_ui_queue);
}
lapdm_entity_set_mode(le, mode);
@@ -296,6 +297,7 @@
for (i = 0; i < ARRAY_SIZE(le->datalink); i++) {
dl = &le->datalink[i];
lapd_dl_exit(&dl->dl);
+ msgb_queue_free(&dl->tx_ui_queue);
}
}
@@ -390,6 +392,33 @@
return le->l1_prim_cb(&pp.oph, le->l1_ctx);
}
+static int tx_ph_data_enqueue_ui(struct lapdm_datalink *dl, struct msgb *msg,
+ uint8_t chan_nr, uint8_t link_id, uint8_t pad)
+{
+ struct lapdm_entity *le = dl->entity;
+ struct osmo_phsap_prim pp;
+
+ /* if there is a pending message, queue it */
+ if (le->tx_pending || le->flags & LAPDM_ENT_F_POLLING_ONLY) {
+ *msgb_push(msg, 1) = pad;
+ *msgb_push(msg, 1) = link_id;
+ *msgb_push(msg, 1) = chan_nr;
+ msgb_enqueue(&dl->tx_ui_queue, msg);
+ return 0;
+ }
+
+ osmo_prim_init(&pp.oph, SAP_GSM_PH, PRIM_PH_DATA,
+ PRIM_OP_REQUEST, msg);
+ pp.u.data.chan_nr = chan_nr;
+ pp.u.data.link_id = link_id;
+
+ /* send the frame now */
+ le->tx_pending = 0; /* disabled flow control */
+ lapdm_pad_msgb(msg, pad);
+
+ return le->l1_prim_cb(&pp.oph, le->l1_ctx);
+}
+
/* Get transmit frame from queue, if any. In polling mode, indicate RTS to LAPD and start T200, if pending. */
static struct msgb *tx_dequeue_msgb(struct lapdm_datalink *dl, uint32_t fn)
{
@@ -420,6 +449,11 @@
msg = msgb_dequeue(&dl->dl.tx_queue);
if (msg)
LOGDL(&dl->dl, LOGL_INFO, "Sending frame from TX queue. (FN %"PRIu32")\n", fn);
+ else {
+ msg = msgb_dequeue(&dl->tx_ui_queue);
+ if (msg)
+ LOGDL(&dl->dl, LOGL_INFO, "Sending UI frame from TX queue. (FN %"PRIu32")\n", fn);
+ }
return msg;
}
@@ -1183,7 +1217,7 @@
}
/* Tramsmit */
- return tx_ph_data_enqueue(dl, msg, chan_nr, link_id, 23);
+ return tx_ph_data_enqueue_ui(dl, msg, chan_nr, link_id, 23);
}
/* L3 requests transfer of acknowledged information */
@@ -1580,6 +1614,7 @@
for (i = 0; i < ARRAY_SIZE(le->datalink); i++) {
dl = &le->datalink[i];
lapd_dl_reset(&dl->dl);
+ msgb_queue_free(&dl->tx_ui_queue);
}
}