chan_alloc: Change Channel Release to release SAPIs, then the channel

Currently every SAPI release indication will trigger the channel. It
was possible that we had SAPI=3 and SAPI=0 allocated and we tried to
release the channel by sending a RF Channel Release, the BTS answered
with a RF Channel Release ACK but also sent the SAPI Release Indication
which triggered a channel release here. So it was possible that we
would have released a newly allocated channel because of the SAPI
release of the old connection.

This code now works by releasing all SAPIs from highest to lowest,
then sending a SACH Deactivate and finally releasing the channel. This
approach is in use on the on-waves/bsc-master.
This commit is contained in:
Holger Hans Peter Freyther 2010-07-29 17:09:36 +08:00
parent aeb45f5186
commit 4b85a32360
4 changed files with 72 additions and 10 deletions

View File

@ -75,6 +75,7 @@ int rsl_lchan_set_state(struct gsm_lchan *lchan, int);
/* to be provided by external code */
int abis_rsl_sendmsg(struct msgb *msg);
int rsl_deact_sacch(struct gsm_lchan *lchan);
int rsl_lchan_rll_release(struct gsm_lchan *lchan, u_int8_t link_id);
/* BCCH related code */
int rsl_ccch_conf_to_bs_cc_chans(int ccch_conf);

View File

@ -278,6 +278,8 @@ struct gsm_lchan {
/* Established data link layer services */
u_int8_t sapis[8];
int sach_deact;
int release_reason;
/* GSM Random Access data */
struct gsm48_req_ref *rqd_ref;

View File

@ -1356,11 +1356,21 @@ static int rsl_rx_rll_err_ind(struct msgb *msg)
static void rsl_handle_release(struct gsm_lchan *lchan)
{
int sapi;
struct gsm_bts *bts;
/* maybe we have only brought down one RLL */
if (lchan->state != LCHAN_S_REL_REQ)
LOGP(DRSL, LOGL_ERROR, "RF release on %s but state %s\n",
gsm_lchan_name(lchan),
gsm_lchans_name(lchan->state));
return;
for (sapi = 0; sapi < ARRAY_SIZE(lchan->sapis); ++sapi) {
if (lchan->sapis[sapi] == LCHAN_SAPI_UNUSED)
continue;
LOGP(DRSL, LOGL_NOTICE, "%s waiting for SAPI=%d to be released.\n",
gsm_lchan_name(lchan), sapi);
return;
}
/* wait a bit to send the RF Channel Release */
@ -1422,6 +1432,7 @@ static int abis_rsl_rx_rll(struct msgb *msg)
rll_indication(msg->lchan, rllh->link_id,
BSC_RLLR_IND_REL_IND);
rsl_handle_release(msg->lchan);
rsl_lchan_rll_release(msg->lchan, rllh->link_id);
break;
case RSL_MT_REL_CONF:
/* BTS informs us of having received UA from MS,
@ -1429,6 +1440,7 @@ static int abis_rsl_rx_rll(struct msgb *msg)
DEBUGPC(DRLL, "RELEASE CONFIRMATION\n");
msg->lchan->sapis[rllh->link_id & 0x7] = LCHAN_SAPI_UNUSED;
rsl_handle_release(msg->lchan);
rsl_lchan_rll_release(msg->lchan, rllh->link_id);
break;
case RSL_MT_ERROR_IND:
rc = rsl_rx_rll_err_ind(msg);

View File

@ -328,6 +328,9 @@ void lchan_free(struct gsm_lchan *lchan)
lchan->conn = NULL;
}
lchan->sach_deact = 0;
lchan->release_reason = 0;
/* FIXME: ts_free() the timeslot, if we're the last logical
* channel using it */
}
@ -352,18 +355,62 @@ void lchan_reset(struct gsm_lchan *lchan)
lchan->state = LCHAN_S_NONE;
}
/* release the next allocated SAPI or return 0 */
static int _lchan_release_next_sapi(struct gsm_lchan *lchan)
{
int sapi;
for (sapi = 1; sapi < ARRAY_SIZE(lchan->sapis); ++sapi) {
u_int8_t link_id;
if (lchan->sapis[sapi] == LCHAN_SAPI_UNUSED)
continue;
link_id = sapi;
if (lchan->type == GSM_LCHAN_TCH_F || lchan->type == GSM_LCHAN_TCH_H)
link_id |= 0x40;
rsl_release_request(lchan, link_id, lchan->release_reason);
return 0;
}
return 1;
}
/* Drive the release process of the lchan */
static void _lchan_handle_release(struct gsm_lchan *lchan)
{
/* Ask for SAPI != 0 to be freed first and stop if we need to wait */
if (_lchan_release_next_sapi(lchan) == 0)
return;
if (lchan->sach_deact) {
gsm48_send_rr_release(lchan);
return;
}
rsl_release_request(lchan, 0, lchan->release_reason);
rsl_lchan_set_state(lchan, LCHAN_S_REL_REQ);
}
/* called from abis rsl */
int rsl_lchan_rll_release(struct gsm_lchan *lchan, u_int8_t link_id)
{
if (lchan->state != LCHAN_S_REL_REQ)
return -1;
if ((link_id & 0x7) != 0)
_lchan_handle_release(lchan);
return 0;
}
/* Consider releasing the channel now */
int lchan_release(struct gsm_lchan *lchan, int sach_deact, int reason)
{
/* Assume we have GSM04.08 running and send a release */
if (sach_deact) {
gsm48_send_rr_release(lchan);
}
DEBUGP(DRLL, "%s Recycling Channel\n", gsm_lchan_name(lchan));
DEBUGP(DRLL, "%s starting release sequence\n", gsm_lchan_name(lchan));
rsl_lchan_set_state(lchan, LCHAN_S_REL_REQ);
rsl_release_request(lchan, 0, 0);
lchan->release_reason = reason;
lchan->sach_deact = sach_deact;
_lchan_handle_release(lchan);
return 1;
}