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.
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@ -75,6 +75,7 @@ int rsl_lchan_set_state(struct gsm_lchan *lchan, int);
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/* to be provided by external code */
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int abis_rsl_sendmsg(struct msgb *msg);
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int rsl_deact_sacch(struct gsm_lchan *lchan);
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int rsl_lchan_rll_release(struct gsm_lchan *lchan, u_int8_t link_id);
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/* BCCH related code */
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int rsl_ccch_conf_to_bs_cc_chans(int ccch_conf);
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@ -278,6 +278,8 @@ struct gsm_lchan {
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/* Established data link layer services */
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u_int8_t sapis[8];
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int sach_deact;
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int release_reason;
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/* GSM Random Access data */
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struct gsm48_req_ref *rqd_ref;
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@ -1356,11 +1356,21 @@ static int rsl_rx_rll_err_ind(struct msgb *msg)
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static void rsl_handle_release(struct gsm_lchan *lchan)
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{
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int sapi;
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struct gsm_bts *bts;
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/* maybe we have only brought down one RLL */
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if (lchan->state != LCHAN_S_REL_REQ)
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LOGP(DRSL, LOGL_ERROR, "RF release on %s but state %s\n",
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gsm_lchan_name(lchan),
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gsm_lchans_name(lchan->state));
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return;
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for (sapi = 0; sapi < ARRAY_SIZE(lchan->sapis); ++sapi) {
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if (lchan->sapis[sapi] == LCHAN_SAPI_UNUSED)
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continue;
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LOGP(DRSL, LOGL_NOTICE, "%s waiting for SAPI=%d to be released.\n",
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gsm_lchan_name(lchan), sapi);
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return;
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}
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/* wait a bit to send the RF Channel Release */
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@ -1422,6 +1432,7 @@ static int abis_rsl_rx_rll(struct msgb *msg)
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rll_indication(msg->lchan, rllh->link_id,
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BSC_RLLR_IND_REL_IND);
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rsl_handle_release(msg->lchan);
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rsl_lchan_rll_release(msg->lchan, rllh->link_id);
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break;
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case RSL_MT_REL_CONF:
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/* BTS informs us of having received UA from MS,
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@ -1429,6 +1440,7 @@ static int abis_rsl_rx_rll(struct msgb *msg)
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DEBUGPC(DRLL, "RELEASE CONFIRMATION\n");
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msg->lchan->sapis[rllh->link_id & 0x7] = LCHAN_SAPI_UNUSED;
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rsl_handle_release(msg->lchan);
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rsl_lchan_rll_release(msg->lchan, rllh->link_id);
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break;
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case RSL_MT_ERROR_IND:
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rc = rsl_rx_rll_err_ind(msg);
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@ -328,6 +328,9 @@ void lchan_free(struct gsm_lchan *lchan)
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lchan->conn = NULL;
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}
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lchan->sach_deact = 0;
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lchan->release_reason = 0;
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/* FIXME: ts_free() the timeslot, if we're the last logical
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* channel using it */
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}
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@ -352,18 +355,62 @@ void lchan_reset(struct gsm_lchan *lchan)
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lchan->state = LCHAN_S_NONE;
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}
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/* release the next allocated SAPI or return 0 */
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static int _lchan_release_next_sapi(struct gsm_lchan *lchan)
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{
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int sapi;
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for (sapi = 1; sapi < ARRAY_SIZE(lchan->sapis); ++sapi) {
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u_int8_t link_id;
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if (lchan->sapis[sapi] == LCHAN_SAPI_UNUSED)
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continue;
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link_id = sapi;
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if (lchan->type == GSM_LCHAN_TCH_F || lchan->type == GSM_LCHAN_TCH_H)
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link_id |= 0x40;
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rsl_release_request(lchan, link_id, lchan->release_reason);
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return 0;
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}
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return 1;
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}
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/* Drive the release process of the lchan */
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static void _lchan_handle_release(struct gsm_lchan *lchan)
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{
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/* Ask for SAPI != 0 to be freed first and stop if we need to wait */
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if (_lchan_release_next_sapi(lchan) == 0)
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return;
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if (lchan->sach_deact) {
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gsm48_send_rr_release(lchan);
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return;
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}
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rsl_release_request(lchan, 0, lchan->release_reason);
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rsl_lchan_set_state(lchan, LCHAN_S_REL_REQ);
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}
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/* called from abis rsl */
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int rsl_lchan_rll_release(struct gsm_lchan *lchan, u_int8_t link_id)
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{
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if (lchan->state != LCHAN_S_REL_REQ)
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return -1;
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if ((link_id & 0x7) != 0)
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_lchan_handle_release(lchan);
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return 0;
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}
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/* Consider releasing the channel now */
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int lchan_release(struct gsm_lchan *lchan, int sach_deact, int reason)
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{
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/* Assume we have GSM04.08 running and send a release */
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if (sach_deact) {
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gsm48_send_rr_release(lchan);
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}
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DEBUGP(DRLL, "%s Recycling Channel\n", gsm_lchan_name(lchan));
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DEBUGP(DRLL, "%s starting release sequence\n", gsm_lchan_name(lchan));
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rsl_lchan_set_state(lchan, LCHAN_S_REL_REQ);
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rsl_release_request(lchan, 0, 0);
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lchan->release_reason = reason;
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lchan->sach_deact = sach_deact;
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_lchan_handle_release(lchan);
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return 1;
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}
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