| /* tbf_dl_fsm.c |
| * |
| * Copyright (C) 2021-2022 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de> |
| * Author: Pau Espin Pedrol <pespin@sysmocom.de> |
| * |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU General Public License |
| * as published by the Free Software Foundation; either version 2 |
| * of the License, or (at your option) any later version. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU General Public License for more details. |
| */ |
| |
| #include <unistd.h> |
| |
| #include <talloc.h> |
| |
| #include <tbf_fsm.h> |
| #include <gprs_rlcmac.h> |
| #include <gprs_debug.h> |
| #include <gprs_ms.h> |
| #include <encoding.h> |
| #include <bts.h> |
| |
| #include <bts_pch_timer.h> |
| |
| #define X(s) (1 << (s)) |
| |
| static const struct osmo_tdef_state_timeout tbf_dl_fsm_timeouts[32] = { |
| [TBF_ST_NEW] = {}, |
| [TBF_ST_ASSIGN] = {}, |
| [TBF_ST_FLOW] = {}, |
| [TBF_ST_FINISHED] = {}, |
| [TBF_ST_WAIT_RELEASE] = { .T = 3192 }, |
| [TBF_ST_WAIT_REUSE_TFI] = { /* .T = 3193 set manually onenter subtracting T3192 */ }, |
| [TBF_ST_RELEASING] = { .T = 3195 }, |
| }; |
| |
| /* Transition to a state, using the T timer defined in tbf_dl_fsm_timeouts. |
| * The actual timeout value is in turn obtained from T_defs_bts. |
| */ |
| #define tbf_dl_fsm_state_chg(fi, NEXT_STATE) \ |
| osmo_tdef_fsm_inst_state_chg(fi, NEXT_STATE, \ |
| tbf_dl_fsm_timeouts, \ |
| tbf_ms(((struct tbf_dl_fsm_ctx *)(fi->priv))->tbf)->bts->T_defs_bts, \ |
| -1) |
| |
| static void mod_ass_type(struct tbf_dl_fsm_ctx *ctx, uint8_t t, bool set) |
| { |
| const char *ch = "UNKNOWN"; |
| bool prev_set = ctx->state_flags & (1 << t); |
| |
| switch (t) { |
| case GPRS_RLCMAC_FLAG_CCCH: |
| ch = "CCCH"; |
| break; |
| case GPRS_RLCMAC_FLAG_PACCH: |
| ch = "PACCH"; |
| break; |
| default: |
| OSMO_ASSERT(0); |
| } |
| |
| LOGPTBFDL(ctx->dl_tbf, LOGL_INFO, "%sset ass. type %s [prev CCCH:%u, PACCH:%u]\n", |
| set ? "" : "un", ch, |
| !!(ctx->state_flags & (1 << GPRS_RLCMAC_FLAG_CCCH)), |
| !!(ctx->state_flags & (1 << GPRS_RLCMAC_FLAG_PACCH))); |
| |
| if (set && prev_set) { |
| LOGPTBFDL(ctx->dl_tbf, LOGL_ERROR, |
| "Attempted to set ass. type %s which is already set\n", ch); |
| return; |
| } |
| |
| if (!set && !prev_set) |
| return; |
| |
| if (set) |
| ctx->state_flags |= (1 << t); |
| else |
| ctx->state_flags &= ~(1 << t); |
| } |
| |
| |
| static void st_new(struct osmo_fsm_inst *fi, uint32_t event, void *data) |
| { |
| struct tbf_dl_fsm_ctx *ctx = (struct tbf_dl_fsm_ctx *)fi->priv; |
| switch (event) { |
| case TBF_EV_ASSIGN_ADD_CCCH: |
| mod_ass_type(ctx, GPRS_RLCMAC_FLAG_CCCH, true); |
| tbf_dl_fsm_state_chg(fi, TBF_ST_ASSIGN); |
| break; |
| case TBF_EV_ASSIGN_ADD_PACCH: |
| mod_ass_type(ctx, GPRS_RLCMAC_FLAG_PACCH, true); |
| tbf_dl_fsm_state_chg(fi, TBF_ST_ASSIGN); |
| break; |
| default: |
| OSMO_ASSERT(0); |
| } |
| } |
| |
| static void st_assign_on_enter(struct osmo_fsm_inst *fi, uint32_t prev_state) |
| { |
| struct tbf_dl_fsm_ctx *ctx = (struct tbf_dl_fsm_ctx *)fi->priv; |
| struct GprsMs *ms = tbf_ms(ctx->tbf); |
| unsigned long val; |
| unsigned int sec, micro; |
| |
| /* If assignment for this TBF is happening on PACCH, that means the |
| * actual Assignment procedure (tx/rx) is happening on another TBF (eg |
| * Ul TBF vs DL TBF). Hence we add a security timer here to free it in |
| * case the other TBF doesn't succeed in informing (assigning) the MS |
| * about this TBF, or simply because the scheduler takes too long to |
| * schedule it. This timer can probably be dropped once we make the |
| * other TBF always signal us assignment failure (we already get |
| * assignment success through TBF_EV_ASSIGN_ACK_PACCH) */ |
| if (ctx->state_flags & (1 << GPRS_RLCMAC_FLAG_PACCH)) { |
| fi->T = -2001; |
| val = osmo_tdef_get(the_pcu->T_defs, fi->T, OSMO_TDEF_MS, -1); |
| sec = val / 1000; |
| micro = (val % 1000) * 1000; |
| LOGPTBFDL(ctx->dl_tbf, LOGL_DEBUG, |
| "Starting timer X2001 [assignment (PACCH)] with %u sec. %u microsec\n", |
| sec, micro); |
| osmo_timer_schedule(&fi->timer, sec, micro); |
| } else { |
| /* GPRS_RLCMAC_FLAG_CCCH is set, so here we submit a DL Ass |
| * through PCUIF on CCCH */ |
| OSMO_ASSERT(ctx->state_flags & (1 << GPRS_RLCMAC_FLAG_CCCH)); |
| /* Send CCCH (PCH) Immediate Assignment over PCUIF: */ |
| bts_snd_dl_ass(ms->bts, ctx->dl_tbf); |
| } |
| } |
| |
| static void st_assign(struct osmo_fsm_inst *fi, uint32_t event, void *data) |
| { |
| struct tbf_dl_fsm_ctx *ctx = (struct tbf_dl_fsm_ctx *)fi->priv; |
| struct GprsMs *ms; |
| unsigned long val; |
| unsigned int sec, micro; |
| |
| switch (event) { |
| case TBF_EV_ASSIGN_ADD_CCCH: |
| /* Note: This code path is not really used nowadays, since ADD_CCCH is |
| * only dispatched during dl_tbf allocation (st=NEW) */ |
| ms = tbf_ms(ctx->tbf); |
| mod_ass_type(ctx, GPRS_RLCMAC_FLAG_CCCH, true); |
| /* Re-send CCCH (PCH) Immediate Assignment over PCUIF: */ |
| bts_snd_dl_ass(ms->bts, ctx->dl_tbf); |
| break; |
| case TBF_EV_ASSIGN_ADD_PACCH: |
| mod_ass_type(ctx, GPRS_RLCMAC_FLAG_PACCH, true); |
| break; |
| case TBF_EV_ASSIGN_ACK_PACCH: |
| tbf_assign_control_ts(ctx->tbf); |
| if (ctx->state_flags & (1 << GPRS_RLCMAC_FLAG_CCCH)) { |
| /* We now know that the PACCH really existed */ |
| LOGPTBFDL(ctx->dl_tbf, LOGL_INFO, |
| "The TBF has been confirmed on the PACCH, " |
| "changed type from CCCH to PACCH\n"); |
| mod_ass_type(ctx, GPRS_RLCMAC_FLAG_CCCH, false); |
| mod_ass_type(ctx, GPRS_RLCMAC_FLAG_PACCH, true); |
| } |
| tbf_dl_fsm_state_chg(fi, TBF_ST_FLOW); |
| break; |
| case TBF_EV_ASSIGN_PCUIF_CNF: |
| /* BTS informs us it sent Imm Ass for DL TBF over CCCH. We now |
| * have to wait for X2002 to trigger (meaning MS is already |
| * listening on PDCH) in order to move to FLOW state and start |
| * transmitting data to it. When X2002 triggers (see cb timer |
| * end of the file) it will send TBF_EV_ASSIGN_READY_CCCH back |
| * to us here. |
| */ |
| if (!(ctx->state_flags & (1 << GPRS_RLCMAC_FLAG_CCCH))) { |
| /* This can happen if we initiated a CCCH DlAss from an |
| * older TBF object (same TLLI) towards BTS, and the DL-TBF |
| * was recreated and is now trying to be assigned through |
| * PACCH. |
| */ |
| LOGPTBFDL(ctx->dl_tbf, LOGL_INFO, |
| "Ignoring event ASSIGN_PCUIF_CNF from BTS " |
| "(CCCH was not requested on current assignment)\n"); |
| break; |
| } |
| fi->T = -2002; |
| val = osmo_tdef_get(the_pcu->T_defs, fi->T, OSMO_TDEF_MS, -1); |
| sec = val / 1000; |
| micro = (val % 1000) * 1000; |
| LOGPTBFDL(ctx->dl_tbf, LOGL_DEBUG, |
| "Starting timer X2002 [assignment (PCH)] with %u sec. %u microsec\n", |
| sec, micro); |
| osmo_timer_schedule(&fi->timer, sec, micro); |
| break; |
| case TBF_EV_ASSIGN_READY_CCCH: |
| /* change state to FLOW, so scheduler will start transmission */ |
| tbf_dl_fsm_state_chg(fi, TBF_ST_FLOW); |
| break; |
| case TBF_EV_MAX_N3105: |
| /* We are going to release, so abort any Pkt Ul Ass pending to be scheduled: */ |
| osmo_fsm_inst_dispatch(tbf_ul_ass_fi(ctx->tbf), TBF_UL_ASS_EV_ABORT, NULL); |
| tbf_dl_fsm_state_chg(fi, TBF_ST_RELEASING); |
| break; |
| default: |
| OSMO_ASSERT(0); |
| } |
| } |
| |
| static void st_flow(struct osmo_fsm_inst *fi, uint32_t event, void *data) |
| { |
| struct tbf_dl_fsm_ctx *ctx = (struct tbf_dl_fsm_ctx *)fi->priv; |
| |
| switch (event) { |
| case TBF_EV_ASSIGN_PCUIF_CNF: |
| if (!(ctx->state_flags & (1 << GPRS_RLCMAC_FLAG_CCCH))) { |
| /* This can happen if we initiated a CCCH DlAss from an |
| * older TBF object (same TLLI) towards BTS, and the DL-TBF |
| * was recreated (this one) and was successfully assigned over PACCH. |
| * This is usually the case if MS requests 2phase access |
| * to get an UL TBF while we were waiting for a DL TBF |
| * assignment for that same MS over PCH. |
| */ |
| LOGPTBFDL(ctx->dl_tbf, LOGL_INFO, |
| "Ignoring event ASSIGN_PCUIF_CNF from BTS " |
| "(CCCH was not requested on current assignment)\n"); |
| } |
| break; |
| case TBF_EV_DL_ACKNACK_MISS: |
| /* DL TBF: we missed a DL ACK/NACK. If we started assignment |
| * over CCCH and never received any DL ACK/NACK yet, it means we |
| * don't even know if the MS successfully received the Imm Ass on |
| * CCCH and hence is listening on PDCH. Let's better refrain |
| * from continuing and start assignment on CCCH again */ |
| if ((ctx->state_flags & (1 << GPRS_RLCMAC_FLAG_CCCH)) && |
| !dl_tbf_first_dl_ack_rcvd(ctx->dl_tbf)) { |
| LOGPTBFDL(ctx->dl_tbf, LOGL_DEBUG, "Retransmit ImmAss[PktDlAss] on PCH\n"); |
| tbf_dl_fsm_state_chg(fi, TBF_ST_ASSIGN); |
| } |
| break; |
| case TBF_EV_LAST_DL_DATA_SENT: |
| /* All data has been sent or received, change state to FINISHED */ |
| tbf_dl_fsm_state_chg(fi, TBF_ST_FINISHED); |
| break; |
| case TBF_EV_MAX_N3105: |
| tbf_dl_fsm_state_chg(fi, TBF_ST_RELEASING); |
| break; |
| default: |
| OSMO_ASSERT(0); |
| } |
| } |
| |
| static void st_finished(struct osmo_fsm_inst *fi, uint32_t event, void *data) |
| { |
| switch (event) { |
| case TBF_EV_DL_ACKNACK_MISS: |
| break; |
| case TBF_EV_FINAL_ACK_RECVD: |
| /* We received Final Ack (DL ACK/NACK) from MS. move to |
| * WAIT_RELEASE, where MS stays monitoring PDCH over T3192 span, |
| * where we can use this DL TBF to assign a new one in case we |
| * receive more DL data to Tx */ |
| tbf_dl_fsm_state_chg(fi, TBF_ST_WAIT_RELEASE); |
| break; |
| case TBF_EV_MAX_N3105: |
| tbf_dl_fsm_state_chg(fi, TBF_ST_RELEASING); |
| break; |
| default: |
| OSMO_ASSERT(0); |
| } |
| } |
| |
| static void st_wait_release_on_enter(struct osmo_fsm_inst *fi, uint32_t prev_state) |
| { |
| struct tbf_dl_fsm_ctx *ctx = (struct tbf_dl_fsm_ctx *)fi->priv; |
| struct GprsMs *ms = tbf_ms(ctx->tbf); |
| |
| /* This state was entered because FinalACK was received; now T3192 is |
| * running on the MS and has also been armed by this FSM. |
| * During that time, it is possible to reach the MS over PACCH to assign |
| * new DL TBF. |
| * Upon T3192 expiration, FSM will transition to TBF_ST_WAIT_REUSE_TFI |
| * for some more time (T3193 - T3192) until internally freeing the TBF |
| * object, at which time the resources can be reused. |
| */ |
| |
| mod_ass_type(ctx, GPRS_RLCMAC_FLAG_CCCH, false); |
| |
| /* check for LLC PDU in the LLC Queue */ |
| if (llc_queue_size(ms_llc_queue(ms)) > 0) { |
| /* we have more data so we will re-use this tbf */ |
| ms_new_dl_tbf_assigned_on_pacch(ms, ctx->tbf); |
| } |
| } |
| |
| static void st_wait_release(struct osmo_fsm_inst *fi, uint32_t event, void *data) |
| { |
| switch (event) { |
| case TBF_EV_FINAL_ACK_RECVD: |
| /* ignore, duplicate ACK, we already know about since we left ST_FINISHED */ |
| break; |
| case TBF_EV_DL_ACKNACK_MISS: |
| /* ignore, miss for retransmitted ACK, but a previous one was |
| * already ACKED since we left ST_FINISHED. This happens due to |
| * fn-advance scheduling several DL blocks in advance. */ |
| break; |
| case TBF_EV_MAX_N3105: |
| /* Triggered potentially by a poll timeout of PKT UL/DL TBF ASS. |
| * Reached N3105, the MS is not responding, so stop attempting |
| * using the TBF for DL assignment and change to ST_RELEASING in |
| * order to simply wait until resources can be reused (see |
| * st_releasing_on_enter()). */ |
| tbf_dl_fsm_state_chg(fi, TBF_ST_RELEASING); |
| break; |
| default: |
| OSMO_ASSERT(0); |
| } |
| } |
| |
| static void st_wait_reuse_tfi_on_enter(struct osmo_fsm_inst *fi, uint32_t prev_state) |
| { |
| struct tbf_dl_fsm_ctx *ctx = (struct tbf_dl_fsm_ctx *)fi->priv; |
| struct GprsMs *ms = tbf_ms(ctx->tbf); |
| unsigned long t3192, t3193, res; |
| |
| /* T3192 has expired, so the MS is not listening on that PACCH anymore. |
| * Still, wait until remaining of T3193 expiration (>T3192) to internally |
| * free the TBF, at which point the TFI and other allocated resources |
| * will be freed and can then be reused. |
| */ |
| |
| t3192 = osmo_tdef_get(ms->bts->T_defs_bts, 3192, OSMO_TDEF_MS, -1); |
| t3193 = osmo_tdef_get(ms->bts->T_defs_bts, 3193, OSMO_TDEF_MS, -1); |
| /* As per spec T3193 shall be greater than T3192, but let's be safe against wrong configs: */ |
| res = (t3193 >= t3192) ? (t3193 - t3192) : 0; |
| fi->T = 3193; |
| LOGPTBF(ctx->tbf, LOGL_DEBUG, "Waiting %lu sec. %lu microsec (T3193 - T3192) [REUSE TFI]\n", |
| res / 1000, (res % 1000) * 1000); |
| osmo_timer_schedule(&fi->timer, res / 1000, (res % 1000) * 1000); |
| } |
| |
| static void st_wait_reuse_tfi(struct osmo_fsm_inst *fi, uint32_t event, void *data) |
| { |
| /* Simply wait for T3193 timeout, it will tbf_free() */ |
| switch (event) { |
| case TBF_EV_FINAL_ACK_RECVD: |
| /* ignore, duplicate ACK, we already know about since we left ST_FINISHED */ |
| break; |
| case TBF_EV_DL_ACKNACK_MISS: |
| /* ignore, miss for retransmitted ACK, but a previous one was |
| * already ACKED since we left ST_FINISHED. This happens due to |
| * fn-advance scheduling several DL blocks in advance. */ |
| break; |
| default: |
| OSMO_ASSERT(0); |
| } |
| } |
| |
| static void st_releasing_on_enter(struct osmo_fsm_inst *fi, uint32_t prev_state) |
| { |
| /* T3195 has been set entering this state: Wait for reuse of TFI(s) when |
| * there is no response from the MS (radio failure or cell change) for this |
| * TBF/MBMS radio bearer. Upon timeout, the timer_cb does tbf_free(). |
| */ |
| } |
| |
| static void st_releasing(struct osmo_fsm_inst *fi, uint32_t event, void *data) |
| { |
| switch (event) { |
| case TBF_EV_DL_ACKNACK_MISS: |
| /* Ignore, we don't care about missed DL ACK/NACK poll timeouts |
| * anymore, we are already releasing the TBF */ |
| break; |
| default: |
| OSMO_ASSERT(0); |
| } |
| } |
| |
| static void handle_timeout_X2002(struct osmo_fsm_inst *fi) |
| { |
| struct tbf_dl_fsm_ctx *ctx = (struct tbf_dl_fsm_ctx *)fi->priv; |
| int rc; |
| |
| if (fi->state != TBF_ST_ASSIGN) { |
| LOGPTBFDL(ctx->dl_tbf, LOGL_NOTICE, "Continue flow after IMM.ASS confirm\n"); |
| return; |
| } |
| |
| /* state TBF_ST_ASSIGN: */ |
| tbf_assign_control_ts(ctx->tbf); |
| |
| if (!tbf_can_upgrade_to_multislot(ctx->tbf)) { |
| /* change state to FLOW, so scheduler will start transmission */ |
| osmo_fsm_inst_dispatch(fi, TBF_EV_ASSIGN_READY_CCCH, NULL); |
| return; |
| } |
| |
| /* This tbf can be upgraded to use multiple DL timeslots and now that there is already |
| * one slot assigned send another DL assignment via PDCH. |
| */ |
| |
| /* Reset state flags */ |
| ctx->state_flags = 0x00; |
| |
| rc = dl_tbf_upgrade_to_multislot(ctx->dl_tbf); |
| if (rc < 0) |
| tbf_free(ctx->tbf); |
| } |
| |
| static int tbf_dl_fsm_timer_cb(struct osmo_fsm_inst *fi) |
| { |
| struct tbf_dl_fsm_ctx *ctx = (struct tbf_dl_fsm_ctx *)fi->priv; |
| switch (fi->T) { |
| case -2002: |
| handle_timeout_X2002(fi); |
| break; |
| case 3192: |
| tbf_dl_fsm_state_chg(fi, TBF_ST_WAIT_REUSE_TFI); |
| break; |
| case -2001: |
| LOGPTBFDL(ctx->dl_tbf, LOGL_NOTICE, "releasing due to PACCH assignment timeout.\n"); |
| /* fall-through */ |
| case 3193: |
| case 3195: |
| tbf_free(ctx->tbf); |
| break; |
| default: |
| OSMO_ASSERT(0); |
| } |
| return 0; |
| } |
| |
| static struct osmo_fsm_state tbf_dl_fsm_states[] = { |
| [TBF_ST_NEW] = { |
| .in_event_mask = |
| X(TBF_EV_ASSIGN_ADD_CCCH) | |
| X(TBF_EV_ASSIGN_ADD_PACCH), |
| .out_state_mask = |
| X(TBF_ST_ASSIGN), |
| .name = "NEW", |
| .action = st_new, |
| }, |
| [TBF_ST_ASSIGN] = { |
| .in_event_mask = |
| X(TBF_EV_ASSIGN_ADD_CCCH) | |
| X(TBF_EV_ASSIGN_ADD_PACCH) | |
| X(TBF_EV_ASSIGN_ACK_PACCH) | |
| X(TBF_EV_ASSIGN_PCUIF_CNF) | |
| X(TBF_EV_ASSIGN_READY_CCCH) | |
| X(TBF_EV_MAX_N3105), |
| .out_state_mask = |
| X(TBF_ST_FLOW) | |
| X(TBF_ST_FINISHED) | |
| X(TBF_ST_RELEASING), |
| .name = "ASSIGN", |
| .action = st_assign, |
| .onenter = st_assign_on_enter, |
| }, |
| [TBF_ST_FLOW] = { |
| .in_event_mask = |
| X(TBF_EV_ASSIGN_PCUIF_CNF) | |
| X(TBF_EV_DL_ACKNACK_MISS) | |
| X(TBF_EV_LAST_DL_DATA_SENT) | |
| X(TBF_EV_MAX_N3105), |
| .out_state_mask = |
| X(TBF_ST_ASSIGN) | |
| X(TBF_ST_FINISHED) | |
| X(TBF_ST_RELEASING), |
| .name = "FLOW", |
| .action = st_flow, |
| }, |
| [TBF_ST_FINISHED] = { |
| .in_event_mask = |
| X(TBF_EV_DL_ACKNACK_MISS) | |
| X(TBF_EV_FINAL_ACK_RECVD) | |
| X(TBF_EV_MAX_N3105), |
| .out_state_mask = |
| X(TBF_ST_WAIT_RELEASE) | |
| X(TBF_ST_RELEASING), |
| .name = "FINISHED", |
| .action = st_finished, |
| }, |
| [TBF_ST_WAIT_RELEASE] = { |
| .in_event_mask = |
| X(TBF_EV_DL_ACKNACK_MISS) | |
| X(TBF_EV_FINAL_ACK_RECVD) | |
| X(TBF_EV_MAX_N3105), |
| .out_state_mask = |
| X(TBF_ST_WAIT_REUSE_TFI) | |
| X(TBF_ST_RELEASING), |
| .name = "WAIT_RELEASE", |
| .action = st_wait_release, |
| .onenter = st_wait_release_on_enter, |
| }, |
| [TBF_ST_WAIT_REUSE_TFI] = { |
| .in_event_mask = |
| X(TBF_EV_DL_ACKNACK_MISS) | |
| X(TBF_EV_FINAL_ACK_RECVD), |
| .out_state_mask = |
| X(TBF_ST_RELEASING), |
| .name = "WAIT_REUSE_TFI", |
| .action = st_wait_reuse_tfi, |
| .onenter = st_wait_reuse_tfi_on_enter, |
| }, |
| [TBF_ST_RELEASING] = { |
| .in_event_mask = |
| X(TBF_EV_DL_ACKNACK_MISS), |
| .out_state_mask = |
| 0, |
| .name = "RELEASING", |
| .action = st_releasing, |
| .onenter = st_releasing_on_enter, |
| }, |
| }; |
| |
| struct osmo_fsm tbf_dl_fsm = { |
| .name = "DL_TBF", |
| .states = tbf_dl_fsm_states, |
| .num_states = ARRAY_SIZE(tbf_dl_fsm_states), |
| .timer_cb = tbf_dl_fsm_timer_cb, |
| .log_subsys = DTBFDL, |
| .event_names = tbf_fsm_event_names, |
| }; |
| |
| static __attribute__((constructor)) void tbf_dl_fsm_init(void) |
| { |
| OSMO_ASSERT(osmo_fsm_register(&tbf_dl_fsm) == 0); |
| } |