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Neels Hofmeyr gerrit-no-reply at lists.osmocom.org
dyn TS: enhance channel allocator for dynamic TS
Change _lc_find_bts() to _lc_dyn_find_bts() with added dyn_as_pchan arg to
pass exactly as which pchan we'd like to allocate on a dynamic TS. Add
_lc_find_bts() as wrapper so non-dynamic-TS callers remain unchanged.
Also add dyn_as_pchan arg to _lc_find_trx() (not renaming to dyn and wrapping
because there is only one caller).
Implement dynamic allocator logic in _lc_find_trx() and lchan_alloc().
A returned dynamic channel still needs to be switched to the proper mode, which
will follow in another commit.
Replace a fixme comment with a normal comment in subslots_per_pchan[], because
handling of dynamic TS is now defined.
Change-Id: I18da7679300c43220d9baa6a304e8df74d366249
---
M openbsc/src/libbsc/chan_alloc.c
1 file changed, 120 insertions(+), 7 deletions(-)
git pull ssh://gerrit.osmocom.org:29418/openbsc refs/changes/98/598/2
diff --git a/openbsc/src/libbsc/chan_alloc.c b/openbsc/src/libbsc/chan_alloc.c
index 046ebfc..f502740 100644
--- a/openbsc/src/libbsc/chan_alloc.c
+++ b/openbsc/src/libbsc/chan_alloc.c
@@ -50,6 +50,13 @@
return 0;
}
+ /* If a dynamic channel is busy changing, it is already taken or not
+ * yet available. */
+ if (ts->pchan == GSM_PCHAN_TCH_F_TCH_H_PDCH) {
+ if (ts->dyn.pchan_is != ts->dyn.pchan_want)
+ return 0;
+ }
+
return 1;
}
@@ -72,17 +79,22 @@
[GSM_PCHAN_TCH_F] = 1,
[GSM_PCHAN_TCH_H] = 2,
[GSM_PCHAN_SDCCH8_SACCH8C] = 8,
- /* FIXME: what about dynamic TCH_F_TCH_H ? */
[GSM_PCHAN_TCH_F_PDCH] = 1,
[GSM_PCHAN_CCCH_SDCCH4_CBCH] = 4,
[GSM_PCHAN_SDCCH8_SACCH8C_CBCH] = 8,
+ /*
+ * GSM_PCHAN_TCH_F_TCH_H_PDCH should not be part of this, those TS are
+ * handled according to their ts->dyn state.
+ */
};
static struct gsm_lchan *
-_lc_find_trx(struct gsm_bts_trx *trx, enum gsm_phys_chan_config pchan)
+_lc_find_trx(struct gsm_bts_trx *trx, enum gsm_phys_chan_config pchan,
+ enum gsm_phys_chan_config dyn_as_pchan)
{
struct gsm_bts_trx_ts *ts;
int j, start, stop, dir, ss;
+ int check_subslots;
if (!trx_is_usable(trx))
return NULL;
@@ -105,8 +117,61 @@
continue;
if (ts->pchan != pchan)
continue;
- /* check if all sub-slots are allocated yet */
- for (ss = 0; ss < subslots_per_pchan[pchan]; ss++) {
+
+ /*
+ * Allocation for fully dynamic timeslots
+ * (does not apply for ip.access style GSM_PCHAN_TCH_F_PDCH)
+ *
+ * Note the special nature of a dynamic timeslot in PDCH mode:
+ * in PDCH mode, typically, lchan->type is GSM_LCHAN_NONE and
+ * lchan->state is LCHAN_S_NONE -- an otherwise unused slot
+ * becomes PDCH implicitly. In the same sense, this channel
+ * allocator will never be asked to find an available PDCH
+ * slot; only TCH/F or TCH/H will be requested, and PDCH mode
+ * means that it is available for switchover.
+ *
+ * A dynamic timeslot in PDCH mode may be switched to TCH/F or
+ * TCH/H. If a dyn TS is already in TCH/F or TCH/H mode, it
+ * means that it is in use and its mode can't be switched.
+ *
+ * The logic concerning channels for TCH/F is trivial: there is
+ * only one channel, so a dynamic TS in TCH/F mode is already
+ * taken and not available for allocation. For TCH/H, we need
+ * to check whether a dynamic timeslot is already in TCH/H mode
+ * and whether one of the two channels is still available.
+ */
+ if (pchan == GSM_PCHAN_TCH_F_TCH_H_PDCH) {
+ if (ts->dyn.pchan_is != ts->dyn.pchan_want) {
+ /* The TS's mode is being switched. Not
+ * available anymore/yet. */
+ DEBUGP(DRLL, "%s already in switchover\n",
+ gsm_ts_and_pchan_name(ts));
+ continue;
+ }
+ if (ts->dyn.pchan_is == GSM_PCHAN_PDCH) {
+ /* This slot is available. Still check for
+ * error states to be sure; in all cases the
+ * first lchan will be used. */
+ if (ts->lchan->state != LCHAN_S_NONE
+ && ts->lchan->state != LCHAN_S_ACTIVE)
+ continue;
+ return ts->lchan;
+ }
+ if (ts->dyn.pchan_is == dyn_as_pchan) {
+ /* The requested type matches the dynamic
+ * timeslot's current mode. A channel may still
+ * be available (think TCH/H). */
+ check_subslots = subslots_per_pchan[ts->dyn.pchan_is];
+ } else
+ /* Otherwise this slot is not applicable. */
+ continue;
+ } else {
+ /* Not a dynamic channel, there is only one pchan kind: */
+ check_subslots = subslots_per_pchan[pchan];
+ }
+
+ /* Is a sub-slot still available? */
+ for (ss = 0; ss < check_subslots; ss++) {
struct gsm_lchan *lc = &ts->lchan[ss];
if (lc->type == GSM_LCHAN_NONE &&
lc->state == LCHAN_S_NONE)
@@ -118,26 +183,33 @@
}
static struct gsm_lchan *
-_lc_find_bts(struct gsm_bts *bts, enum gsm_phys_chan_config pchan)
+_lc_dyn_find_bts(struct gsm_bts *bts, enum gsm_phys_chan_config pchan,
+ enum gsm_phys_chan_config dyn_as_pchan)
{
struct gsm_bts_trx *trx;
struct gsm_lchan *lc;
if (bts->chan_alloc_reverse) {
llist_for_each_entry_reverse(trx, &bts->trx_list, list) {
- lc = _lc_find_trx(trx, pchan);
+ lc = _lc_find_trx(trx, pchan, dyn_as_pchan);
if (lc)
return lc;
}
} else {
llist_for_each_entry(trx, &bts->trx_list, list) {
- lc = _lc_find_trx(trx, pchan);
+ lc = _lc_find_trx(trx, pchan, dyn_as_pchan);
if (lc)
return lc;
}
}
return NULL;
+}
+
+static struct gsm_lchan *
+_lc_find_bts(struct gsm_bts *bts, enum gsm_phys_chan_config pchan)
+{
+ return _lc_dyn_find_bts(bts, pchan, GSM_PCHAN_NONE);
}
/* Allocate a logical channel.
@@ -198,6 +270,18 @@
if (lchan)
type = GSM_LCHAN_TCH_F;
}
+
+ /* try fully dynamic TCH/F_TCH/H_PDCH */
+ if (lchan == NULL) {
+ lchan = _lc_dyn_find_bts(bts, GSM_PCHAN_TCH_F_TCH_H_PDCH,
+ GSM_PCHAN_TCH_H);
+ if (lchan)
+ type = GSM_LCHAN_TCH_H;
+ }
+ /*
+ * No need to check fully dynamic channels for TCH/F:
+ * if no TCH/H was available, neither will be TCH/F.
+ */
}
break;
case GSM_LCHAN_TCH_F:
@@ -216,6 +300,22 @@
if (lchan)
type = GSM_LCHAN_TCH_F;
}
+ /* Try fully dynamic TCH/F_TCH/H_PDCH as TCH/F... */
+ if (!lchan) {
+ lchan = _lc_dyn_find_bts(bts,
+ GSM_PCHAN_TCH_F_TCH_H_PDCH,
+ GSM_PCHAN_TCH_F);
+ if (lchan)
+ type = GSM_LCHAN_TCH_F;
+ }
+ /* ...and as TCH/H. */
+ if (!lchan) {
+ lchan = _lc_dyn_find_bts(bts,
+ GSM_PCHAN_TCH_F_TCH_H_PDCH,
+ GSM_PCHAN_TCH_H);
+ if (lchan)
+ type = GSM_LCHAN_TCH_H;
+ }
break;
case GSM_LCHAN_TCH_H:
lchan =_lc_find_bts(bts, GSM_PCHAN_TCH_H);
@@ -225,6 +325,19 @@
if (lchan)
type = GSM_LCHAN_TCH_F;
}
+ /* No dedicated TCH/x available -- try fully dynamic
+ * TCH/F_TCH/H_PDCH */
+ if (!lchan) {
+ lchan = _lc_dyn_find_bts(bts,
+ GSM_PCHAN_TCH_F_TCH_H_PDCH,
+ GSM_PCHAN_TCH_H);
+ if (lchan)
+ type = GSM_LCHAN_TCH_H;
+ }
+ /*
+ * No need to check TCH/F_TCH/H_PDCH channels for TCH/F:
+ * if no TCH/H was available, neither will be TCH/F.
+ */
/* If we don't have TCH/F either, try dynamic TCH/F_PDCH */
if (!lchan) {
lchan = _lc_find_bts(bts, GSM_PCHAN_TCH_F_PDCH);
--
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Gerrit-MessageType: newpatchset
Gerrit-Change-Id: I18da7679300c43220d9baa6a304e8df74d366249
Gerrit-PatchSet: 2
Gerrit-Project: openbsc
Gerrit-Branch: master
Gerrit-Owner: Neels Hofmeyr <nhofmeyr at sysmocom.de>