/* tbf_ul_fsm.c * * Copyright (C) 2021-2022 by sysmocom - s.f.m.c. GmbH * Author: Pau Espin Pedrol * * 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 #include #include #include #include #include #include #include #include #define X(s) (1 << (s)) static const struct osmo_tdef_state_timeout tbf_ul_fsm_timeouts[32] = { [TBF_ST_NEW] = {}, [TBF_ST_ASSIGN] = {}, [TBF_ST_FLOW] = {}, [TBF_ST_FINISHED] = {}, [TBF_ST_RELEASING] = { .T = 3169 }, }; /* Transition to a state, using the T timer defined in tbf_fsm_timeouts. * The actual timeout value is in turn obtained from conn->T_defs. * Assumes local variable fi exists. */ #define tbf_ul_fsm_state_chg(fi, NEXT_STATE) \ osmo_tdef_fsm_inst_state_chg(fi, NEXT_STATE, \ tbf_ul_fsm_timeouts, \ tbf_ms(((struct tbf_ul_fsm_ctx *)(fi->priv))->tbf)->bts->T_defs_bts, \ -1) static void mod_ass_type(struct tbf_ul_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); } LOGPTBFUL(ctx->ul_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) { LOGPTBFUL(ctx->ul_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_ul_fsm_ctx *ctx = (struct tbf_ul_fsm_ctx *)fi->priv; switch (event) { case TBF_EV_ASSIGN_ADD_CCCH: mod_ass_type(ctx, GPRS_RLCMAC_FLAG_CCCH, true); tbf_ul_fsm_state_chg(fi, TBF_ST_ASSIGN); ul_tbf_contention_resolution_start(ctx->ul_tbf); break; case TBF_EV_ASSIGN_ADD_PACCH: mod_ass_type(ctx, GPRS_RLCMAC_FLAG_PACCH, true); tbf_ul_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_ul_fsm_ctx *ctx = (struct tbf_ul_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 = 3168; val = osmo_tdef_get(ms->bts->T_defs_bts, fi->T, OSMO_TDEF_MS, -1); val *= 4; /* 4 PKT RES REQ retransmit */ sec = val / 1000; micro = (val % 1000) * 1000; LOGPTBFUL(ctx->ul_tbf, LOGL_DEBUG, "Starting timer T3168 [UL TBF Ass (PACCH)] with %u sec. %u microsec\n", sec, micro); osmo_timer_schedule(&fi->timer, sec, micro); } else if (ctx->state_flags & (1 << GPRS_RLCMAC_FLAG_CCCH)) { /* Wait a bit for the AGCH ImmAss[PktUlAss] sent BSC->BTS to * arrive at the MS, and for the MS to jump and starting * listening on USFs in the assigned PDCH. * Ideally we would first wait for TBF_EV_ASSIGN_PCUIF_CNF to * account for queueing time, but that's only sent for data on PCH * so far, while ImmAss for UL TBF is sent on AGCH. */ fi->T = -2002; val = osmo_tdef_get(the_pcu->T_defs, fi->T, OSMO_TDEF_MS, -1); sec = val / 1000; micro = (val % 1000) * 1000; LOGPTBFUL(ctx->ul_tbf, LOGL_DEBUG, "Starting timer X2002 [assignment (AGCH)] with %u sec. %u microsec\n", sec, micro); osmo_timer_schedule(&fi->timer, sec, micro); } } static void st_assign(struct osmo_fsm_inst *fi, uint32_t event, void *data) { struct tbf_ul_fsm_ctx *ctx = (struct tbf_ul_fsm_ctx *)fi->priv; switch (event) { case TBF_EV_ASSIGN_ADD_CCCH: mod_ass_type(ctx, GPRS_RLCMAC_FLAG_CCCH, true); 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 */ LOGPTBFUL(ctx->ul_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_ul_fsm_state_chg(fi, TBF_ST_FLOW); break; case TBF_EV_ASSIGN_READY_CCCH: /* change state to FLOW, so scheduler will start requesting USF */ tbf_ul_fsm_state_chg(fi, TBF_ST_FLOW); break; default: OSMO_ASSERT(0); } } static void st_flow(struct osmo_fsm_inst *fi, uint32_t event, void *data) { struct tbf_ul_fsm_ctx *ctx = (struct tbf_ul_fsm_ctx *)fi->priv; struct GprsMs *ms = tbf_ms(ctx->tbf); struct gprs_rlcmac_dl_tbf *dl_tbf = NULL; switch (event) { case TBF_EV_FIRST_UL_DATA_RECVD: /* TS 44.060 7a.2.1.1: "The contention resolution is completed on * the network side when the network receives an RLC data block that * comprises the TLLI value that identifies the mobile station and the * TFI value associated with the TBF." */ bts_pch_timer_stop(ms->bts, ms); /* We may still have some DL-TBF waiting for assignment in PCH, * which clearly won't happen since the MS is on PDCH now. Get rid * of it, it will be re-assigned on PACCH when contention * resolution at the MS side is done (1st UL ACK/NACK sent) */ if ((dl_tbf = ms_dl_tbf(ms))) { /* Get rid of previous finished UL TBF before providing a new one */ LOGPTBFDL(dl_tbf, LOGL_NOTICE, "Got first UL data while DL-TBF pending, killing it\n"); tbf_free(dl_tbf_as_tbf(dl_tbf)); dl_tbf = NULL; } break; case TBF_EV_CONTENTION_RESOLUTION_MS_SUCCESS: ul_tbf_contention_resolution_success(tbf_as_ul_tbf(ctx->tbf)); break; case TBF_EV_LAST_UL_DATA_RECVD: /* All data has been sent or received, change state to FINISHED */ tbf_ul_fsm_state_chg(fi, TBF_ST_FINISHED); break; case TBF_EV_MAX_N3101: tbf_ul_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) { struct tbf_ul_fsm_ctx *ctx = (struct tbf_ul_fsm_ctx *)fi->priv; struct GprsMs *ms; bool new_ul_tbf_requested; switch (event) { case TBF_EV_CONTENTION_RESOLUTION_MS_SUCCESS: /* UL TBF: If MS only sends 1 RLCMAC UL block, it can be that we * end up in FINISHED state before sending the first UL ACK/NACK */ ul_tbf_contention_resolution_success(tbf_as_ul_tbf(ctx->tbf)); break; case TBF_EV_FINAL_UL_ACK_CONFIRMED: new_ul_tbf_requested = (bool)data; /* Ref the MS, otherwise it may be freed after ul_tbf is * detached when sending event below. */ ms = tbf_ms(ctx->tbf); ms_ref(ms, __func__); /* UL TBF ACKed our transmitted UL ACK/NACK with final Ack * Indicator set to '1'. We can free the TBF right away, the MS * also just released its TBF on its side. */ LOGPTBFUL(tbf_as_ul_tbf(ctx->tbf), LOGL_DEBUG, "[UPLINK] END\n"); tbf_free(ctx->tbf); /* Here fi, ctx and ctx->tbf are already freed! */ /* TS 44.060 9.3.3.3.2: There might be LLC packets waiting in * the queue but the DL TBF assignment might have been delayed * because there was no way to reach the MS (because ul_tbf was * in packet-active mode with FINISHED state). If MS is going * back to packet-idle mode then we can assign the DL TBF on PCH * now. */ if (!new_ul_tbf_requested && ms_need_dl_tbf(ms)) ms_new_dl_tbf_assigned_on_pch(ms); ms_unref(ms, __func__); break; case TBF_EV_MAX_N3103: tbf_ul_fsm_state_chg(fi, TBF_ST_RELEASING); break; default: OSMO_ASSERT(0); } } static void st_releasing_on_enter(struct osmo_fsm_inst *fi, uint32_t prev_state) { /* T3169 has been set entering this state: Wait for reuse of USF and * TFI(s) after the MS uplink assignment for this TBF is invalid. Upon * timeout, the timer_cb does tbf_free(). */ } static void st_releasing(struct osmo_fsm_inst *fi, uint32_t event, void *data) { switch (event) { default: OSMO_ASSERT(0); } } static int tbf_ul_fsm_timer_cb(struct osmo_fsm_inst *fi) { struct tbf_ul_fsm_ctx *ctx = (struct tbf_ul_fsm_ctx *)fi->priv; switch (fi->T) { case -2002: osmo_fsm_inst_dispatch(fi, TBF_EV_ASSIGN_READY_CCCH, NULL); break; case 3168: LOGPTBFUL(ctx->ul_tbf, LOGL_NOTICE, "Releasing due to UL TBF PACCH assignment timeout\n"); /* fall-through */ case 3169: tbf_free(ctx->tbf); break; default: OSMO_ASSERT(0); } return 0; } static struct osmo_fsm_state tbf_ul_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) | X(TBF_ST_FLOW), .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_READY_CCCH), .out_state_mask = X(TBF_ST_FLOW) | X(TBF_ST_FINISHED), .name = "ASSIGN", .action = st_assign, .onenter = st_assign_on_enter, }, [TBF_ST_FLOW] = { .in_event_mask = X(TBF_EV_FIRST_UL_DATA_RECVD) | X(TBF_EV_CONTENTION_RESOLUTION_MS_SUCCESS) | X(TBF_EV_LAST_UL_DATA_RECVD) | X(TBF_EV_MAX_N3101), .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_CONTENTION_RESOLUTION_MS_SUCCESS) | X(TBF_EV_FINAL_UL_ACK_CONFIRMED) | X(TBF_EV_MAX_N3103), .out_state_mask = X(TBF_ST_RELEASING), .name = "FINISHED", .action = st_finished, }, [TBF_ST_RELEASING] = { .in_event_mask = 0, .out_state_mask = 0, .name = "RELEASING", .action = st_releasing, .onenter = st_releasing_on_enter, }, }; struct osmo_fsm tbf_ul_fsm = { .name = "UL_TBF", .states = tbf_ul_fsm_states, .num_states = ARRAY_SIZE(tbf_ul_fsm_states), .timer_cb = tbf_ul_fsm_timer_cb, .log_subsys = DTBFUL, .event_names = tbf_fsm_event_names, }; static __attribute__((constructor)) void tbf_ul_fsm_init(void) { OSMO_ASSERT(osmo_fsm_register(&tbf_ul_fsm) == 0); }