Harald Welte | 136e737 | 2016-05-29 10:53:17 +0900 | [diff] [blame] | 1 | /* Osmocom generic Finite State Machine implementation |
| 2 | * |
| 3 | * (C) 2016 by Harald Welte <laforge@gnumonks.org> |
| 4 | * |
| 5 | * This program is free software; you can redistribute it and/or modify |
| 6 | * it under the terms of the GNU General Public License as published by |
| 7 | * the Free Software Foundation; either version 2 of the License, or |
| 8 | * (at your option) any later version. |
| 9 | * |
| 10 | * This program is distributed in the hope that it will be useful, |
| 11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 13 | * GNU General Public License for more details. |
| 14 | * |
| 15 | * You should have received a copy of the GNU General Public License |
| 16 | * along with this program; if not, write to the Free Software |
| 17 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, |
| 18 | * MA 02110-1301, USA. |
| 19 | */ |
| 20 | |
| 21 | #include <errno.h> |
| 22 | #include <stdbool.h> |
| 23 | |
| 24 | #include <osmocom/core/fsm.h> |
| 25 | #include <osmocom/core/talloc.h> |
| 26 | #include <osmocom/core/logging.h> |
| 27 | #include <osmocom/core/utils.h> |
| 28 | |
| 29 | /*! \addtogroup fsm |
| 30 | * @{ |
| 31 | */ |
| 32 | |
| 33 | /*! \file fsm.c |
| 34 | * \brief Finite State Machine abstraction |
| 35 | * |
| 36 | * This is a generic C-language abstraction for implementing finite |
| 37 | * state machines within the Osmocom framework. It is intended to |
| 38 | * replace existing hand-coded or even only implicitly existing FSMs |
| 39 | * all over the existing code base. |
| 40 | * |
| 41 | * An libosmocore FSM is described by its \ref osmo_fsm description, |
| 42 | * which in turn refers to an array of \ref osmo_fsm_state descriptor, |
| 43 | * each describing a single state in the FSM. |
| 44 | * |
| 45 | * The general idea is that all actions performed within one state are |
| 46 | * located at one position in the code (the state's action function), |
| 47 | * as opposed to the 'message-centric' view of e.g. the existing |
| 48 | * state machines of the LAPD(m) coe, where there is one message for |
| 49 | * eahc possible event (primitive), and the function then needs to |
| 50 | * concern itself on how to handle that event over all possible states. |
| 51 | * |
| 52 | * For each state, there is a bit-mask of permitted input events for |
| 53 | * this state, as well as a bit-mask of permitted new output states to |
| 54 | * which the state can change. Furthermore, there is a function |
| 55 | * pointer implementing the actual handling of the input events |
| 56 | * occurring whilst in thta state. |
| 57 | * |
| 58 | * Furthermore, each state offers a function pointer that can be |
| 59 | * executed just before leaving a state, and another one just after |
| 60 | * entering a state. |
| 61 | * |
| 62 | * When transitioning into a new state, an optional timer number and |
| 63 | * time-out can be passed along. The timer is started just after |
| 64 | * entering the new state, and will call the \ref osmo_fsm timer_cb |
| 65 | * function once it expires. This is intended to be used in telecom |
| 66 | * state machines where a given timer (identified by a certain number) |
| 67 | * is started to terminate the fsm or terminate the fsm once expected |
| 68 | * events are not happening before timeout expiration. |
| 69 | * |
| 70 | * As there can often be many concurrent FSMs of one given class, we |
| 71 | * introduce the concept of \ref osmo_fsm_inst, i.e. an FSM instance. |
| 72 | * The instance keeps the actual state, while the \ref osmo_fsm |
| 73 | * descriptor contains the static/const descriptor of the FSM's states |
| 74 | * and possible transitions. |
| 75 | * |
| 76 | * osmo_fsm are integrated with the libosmocore logging system. The |
| 77 | * logging sub-system is determined by the FSM descriptor, as we assume |
| 78 | * one FSM (let's say one related to a location update procedure) is |
| 79 | * inevitably always tied to a sub-system. The logging level however |
| 80 | * is configurable for each FSM instance, to ensure that e.g. DEBUG |
| 81 | * logging can be used for the LU procedure of one subscriber, while |
| 82 | * NOTICE level is used for all other subscribers. |
| 83 | * |
| 84 | * In order to attach private state to the \ref osmo_fsm_inst, it |
| 85 | * offers an opaque priv pointer. |
| 86 | * |
| 87 | */ |
| 88 | |
| 89 | static LLIST_HEAD(g_fsms); |
| 90 | static bool fsm_log_addr = true; |
| 91 | |
| 92 | /*! \brief specify if FSM instance addresses should be logged or not |
| 93 | * |
| 94 | * By default, the FSM name includes the pointer address of the \ref |
| 95 | * osmo_fsm_inst. This behaviro can be disabled (and re-enabled) |
| 96 | * using this function. |
| 97 | * |
| 98 | * \param[in] log_addr Indicate if FSM instance address shall be logged |
| 99 | */ |
| 100 | void osmo_fsm_log_addr(bool log_addr) |
| 101 | { |
Max | 61281f4 | 2016-11-01 10:49:31 +0100 | [diff] [blame] | 102 | fsm_log_addr = log_addr; |
Harald Welte | 136e737 | 2016-05-29 10:53:17 +0900 | [diff] [blame] | 103 | } |
| 104 | |
| 105 | /*! \brief register a FSM with the core |
| 106 | * |
| 107 | * A FSM descriptor needs to be registered with the core before any |
| 108 | * instances can be created for it. |
| 109 | * |
| 110 | * \param[in] fsm Descriptor of Finite State Machine to be registered |
| 111 | * \returns 0 on success; negative on error |
| 112 | */ |
| 113 | int osmo_fsm_register(struct osmo_fsm *fsm) |
| 114 | { |
| 115 | /* FIXME:check for duplicate name? */ |
| 116 | llist_add_tail(&fsm->list, &g_fsms); |
| 117 | INIT_LLIST_HEAD(&fsm->instances); |
| 118 | |
| 119 | return 0; |
| 120 | } |
| 121 | |
| 122 | /*! \brief unregister a FSM from the core |
| 123 | * |
| 124 | * Once the FSM descriptor is unregistered, active instances can still |
| 125 | * use it, but no new instances may be created for it. |
| 126 | * |
| 127 | * \param[in] fsm Descriptor of Finite State Machine to be removed |
| 128 | */ |
| 129 | void osmo_fsm_unregister(struct osmo_fsm *fsm) |
| 130 | { |
| 131 | llist_del(&fsm->list); |
| 132 | } |
| 133 | |
| 134 | /* small wrapper function around timer expiration (for logging) */ |
| 135 | static void fsm_tmr_cb(void *data) |
| 136 | { |
| 137 | struct osmo_fsm_inst *fi = data; |
| 138 | struct osmo_fsm *fsm = fi->fsm; |
Harald Welte | f627c0f | 2016-06-18 10:36:25 +0200 | [diff] [blame] | 139 | uint32_t T = fi->T; |
Harald Welte | 136e737 | 2016-05-29 10:53:17 +0900 | [diff] [blame] | 140 | |
| 141 | LOGPFSM(fi, "Timeout of T%u\n", fi->T); |
| 142 | |
Harald Welte | f627c0f | 2016-06-18 10:36:25 +0200 | [diff] [blame] | 143 | if (fsm->timer_cb) { |
| 144 | int rc = fsm->timer_cb(fi); |
| 145 | if (rc != 1) |
| 146 | return; |
| 147 | LOGPFSM(fi, "timer_cb requested termination\n"); |
| 148 | } else |
| 149 | LOGPFSM(fi, "No timer_cb, automatic termination\n"); |
| 150 | |
| 151 | /* if timer_cb returns 1 or there is no timer_cb */ |
| 152 | osmo_fsm_inst_term(fi, OSMO_FSM_TERM_TIMEOUT, &T); |
Harald Welte | 136e737 | 2016-05-29 10:53:17 +0900 | [diff] [blame] | 153 | } |
| 154 | |
| 155 | /*! \brief allocate a new instance of a specified FSM |
| 156 | * \param[in] fsm Descriptor of the FSM |
| 157 | * \param[in] ctx talloc context from which to allocate memory |
| 158 | * \param[in] priv private data reference store in fsm instance |
| 159 | * \param[in] log_level The log level for events of this FSM |
| 160 | * \returns newly-allocated, initialized and registered FSM instance |
| 161 | */ |
| 162 | struct osmo_fsm_inst *osmo_fsm_inst_alloc(struct osmo_fsm *fsm, void *ctx, void *priv, |
| 163 | int log_level, const char *id) |
| 164 | { |
| 165 | struct osmo_fsm_inst *fi = talloc_zero(ctx, struct osmo_fsm_inst); |
| 166 | |
| 167 | fi->fsm = fsm; |
| 168 | fi->priv = priv; |
| 169 | fi->log_level = log_level; |
| 170 | fi->timer.data = fi; |
| 171 | fi->timer.cb = fsm_tmr_cb; |
Harald Welte | f323911 | 2016-07-10 15:11:45 +0200 | [diff] [blame] | 172 | if (id) |
| 173 | fi->id = talloc_strdup(fi, id); |
Harald Welte | 136e737 | 2016-05-29 10:53:17 +0900 | [diff] [blame] | 174 | |
| 175 | if (!fsm_log_addr) { |
| 176 | if (id) |
| 177 | fi->name = talloc_asprintf(fi, "%s(%s)", fsm->name, id); |
| 178 | else |
| 179 | fi->name = talloc_asprintf(fi, "%s", fsm->name); |
| 180 | } else { |
| 181 | if (id) |
| 182 | fi->name = talloc_asprintf(fi, "%s(%s)[%p]", fsm->name, |
| 183 | id, fi); |
| 184 | else |
| 185 | fi->name = talloc_asprintf(fi, "%s[%p]", fsm->name, fi); |
| 186 | } |
| 187 | |
| 188 | INIT_LLIST_HEAD(&fi->proc.children); |
| 189 | INIT_LLIST_HEAD(&fi->proc.child); |
| 190 | llist_add(&fi->list, &fsm->instances); |
| 191 | |
| 192 | LOGPFSM(fi, "Allocated\n"); |
| 193 | |
| 194 | return fi; |
| 195 | } |
| 196 | |
| 197 | /*! \brief allocate a new instance of a specified FSM as child of |
| 198 | * other FSM instance |
| 199 | * |
| 200 | * This is like \ref osmo_fsm_inst_alloc but using the parent FSM as |
| 201 | * talloc context, and inheriting the log level of the parent. |
| 202 | * |
| 203 | * \param[in] fsm Descriptor of the to-be-allocated FSM |
| 204 | * \param[in] parent Parent FSM instance |
| 205 | * \param[in] parent_term_event Event to be sent to parent when terminating |
| 206 | * \returns newly-allocated, initialized and registered FSM instance |
| 207 | */ |
| 208 | struct osmo_fsm_inst *osmo_fsm_inst_alloc_child(struct osmo_fsm *fsm, |
| 209 | struct osmo_fsm_inst *parent, |
| 210 | uint32_t parent_term_event) |
| 211 | { |
| 212 | struct osmo_fsm_inst *fi; |
| 213 | |
| 214 | fi = osmo_fsm_inst_alloc(fsm, parent, NULL, parent->log_level, |
| 215 | parent->id); |
| 216 | if (!fi) { |
| 217 | /* indicate immediate termination to caller */ |
| 218 | osmo_fsm_inst_dispatch(parent, parent_term_event, NULL); |
| 219 | return NULL; |
| 220 | } |
| 221 | |
| 222 | LOGPFSM(fi, "is child of %s\n", osmo_fsm_inst_name(parent)); |
| 223 | |
| 224 | fi->proc.parent = parent; |
| 225 | fi->proc.parent_term_event = parent_term_event; |
| 226 | llist_add(&fi->proc.child, &parent->proc.children); |
| 227 | |
| 228 | return fi; |
| 229 | } |
| 230 | |
| 231 | /*! \brief delete a given instance of a FSM |
| 232 | * \param[in] fsm The FSM to be un-registered and deleted |
| 233 | */ |
| 234 | void osmo_fsm_inst_free(struct osmo_fsm_inst *fi) |
| 235 | { |
Max | 3de97e1 | 2016-11-02 10:37:58 +0100 | [diff] [blame^] | 236 | LOGPFSM(fi, "Deallocated\n"); |
Harald Welte | 136e737 | 2016-05-29 10:53:17 +0900 | [diff] [blame] | 237 | osmo_timer_del(&fi->timer); |
| 238 | llist_del(&fi->list); |
| 239 | talloc_free(fi); |
| 240 | } |
| 241 | |
| 242 | /*! \brief get human-readable name of FSM event |
| 243 | * \param[in] fsm FSM descriptor of event |
| 244 | * \param[in] event Event integer value |
| 245 | * \returns string rendering of the event |
| 246 | */ |
| 247 | const char *osmo_fsm_event_name(struct osmo_fsm *fsm, uint32_t event) |
| 248 | { |
| 249 | static char buf[32]; |
| 250 | if (!fsm->event_names) { |
| 251 | snprintf(buf, sizeof(buf), "%u", event); |
| 252 | return buf; |
| 253 | } else |
| 254 | return get_value_string(fsm->event_names, event); |
| 255 | } |
| 256 | |
| 257 | /*! \brief get human-readable name of FSM instance |
| 258 | * \param[in] fi FSM instance |
| 259 | * \returns string rendering of the FSM identity |
| 260 | */ |
| 261 | const char *osmo_fsm_inst_name(struct osmo_fsm_inst *fi) |
| 262 | { |
| 263 | if (!fi) |
| 264 | return "NULL"; |
| 265 | |
| 266 | if (fi->name) |
| 267 | return fi->name; |
| 268 | else |
| 269 | return fi->fsm->name; |
| 270 | } |
| 271 | |
| 272 | /*! \brief get human-readable name of FSM instance |
| 273 | * \param[in] fsm FSM descriptor |
| 274 | * \param[in] state FSM state number |
| 275 | * \returns string rendering of the FSM state |
| 276 | */ |
| 277 | const char *osmo_fsm_state_name(struct osmo_fsm *fsm, uint32_t state) |
| 278 | { |
| 279 | static char buf[32]; |
| 280 | if (state >= fsm->num_states) { |
| 281 | snprintf(buf, sizeof(buf), "unknown %u", state); |
| 282 | return buf; |
| 283 | } else |
| 284 | return fsm->states[state].name; |
| 285 | } |
| 286 | |
| 287 | /*! \brief perform a state change of the given FSM instance |
| 288 | * |
| 289 | * All changes to the FSM instance state must be made via this |
| 290 | * function. It verifies that the existing state actually permits a |
| 291 | * transiiton to new_state. |
| 292 | * |
| 293 | * timeout_secs and T are optional parameters, and only have any effect |
| 294 | * if timeout_secs is not 0. If the timeout function is used, then the |
| 295 | * new_state is entered, and the FSM instances timer is set to expire |
| 296 | * in timeout_secs functions. At that time, the FSM's timer_cb |
| 297 | * function will be called for handling of the timeout by the user. |
| 298 | * |
| 299 | * \param[in] fi FSM instance whose state is to change |
| 300 | * \param[in] new_state The new state into which we should change |
| 301 | * \param[in] timeout_secs Timeout in seconds (if !=0) |
| 302 | * \param[in] T Timer number (if \ref timeout_secs != 0) |
| 303 | * \returns 0 on success; negative on error |
| 304 | */ |
| 305 | int osmo_fsm_inst_state_chg(struct osmo_fsm_inst *fi, uint32_t new_state, |
| 306 | unsigned long timeout_secs, int T) |
| 307 | { |
| 308 | struct osmo_fsm *fsm = fi->fsm; |
| 309 | uint32_t old_state = fi->state; |
| 310 | const struct osmo_fsm_state *st = &fsm->states[fi->state]; |
| 311 | |
| 312 | /* validate if new_state is a valid state */ |
| 313 | if (!(st->out_state_mask & (1 << new_state))) { |
| 314 | LOGP(fsm->log_subsys, LOGL_ERROR, "%s(%s): transition to " |
| 315 | "state %s not permitted!\n", |
| 316 | osmo_fsm_inst_name(fi), |
| 317 | osmo_fsm_state_name(fsm, fi->state), |
| 318 | osmo_fsm_state_name(fsm, new_state)); |
| 319 | return -EPERM; |
| 320 | } |
| 321 | |
Harald Welte | 02a6672 | 2016-07-10 15:13:51 +0200 | [diff] [blame] | 322 | /* delete the old timer */ |
| 323 | osmo_timer_del(&fi->timer); |
| 324 | |
Harald Welte | 136e737 | 2016-05-29 10:53:17 +0900 | [diff] [blame] | 325 | if (st->onleave) |
| 326 | st->onleave(fi, new_state); |
| 327 | |
| 328 | LOGPFSM(fi, "state_chg to %s\n", osmo_fsm_state_name(fsm, new_state)); |
| 329 | fi->state = new_state; |
Harald Welte | 460f9ef | 2016-08-01 00:38:36 +0200 | [diff] [blame] | 330 | st = &fsm->states[new_state]; |
Harald Welte | 136e737 | 2016-05-29 10:53:17 +0900 | [diff] [blame] | 331 | |
Harald Welte | 136e737 | 2016-05-29 10:53:17 +0900 | [diff] [blame] | 332 | if (timeout_secs) { |
Harald Welte | f627c0f | 2016-06-18 10:36:25 +0200 | [diff] [blame] | 333 | fi->T = T; |
| 334 | osmo_timer_schedule(&fi->timer, timeout_secs, 0); |
Harald Welte | 136e737 | 2016-05-29 10:53:17 +0900 | [diff] [blame] | 335 | } |
| 336 | |
Harald Welte | 673018f | 2016-07-10 15:09:43 +0200 | [diff] [blame] | 337 | /* Call 'onenter' last, user might terminate FSM from there */ |
| 338 | if (st->onenter) |
| 339 | st->onenter(fi, old_state); |
| 340 | |
Harald Welte | 136e737 | 2016-05-29 10:53:17 +0900 | [diff] [blame] | 341 | return 0; |
| 342 | } |
| 343 | |
| 344 | /*! \brief dispatch an event to an osmocom finite state machine instance |
| 345 | * |
| 346 | * Any incoming events to \ref osmo_fsm instances must be dispatched to |
| 347 | * them via this function. It verifies, whether the event is permitted |
| 348 | * based on the current state of the FSM. If not, -1 is returned. |
| 349 | * |
| 350 | * \param[in] fi FSM instance |
| 351 | * \param[in] event Event to send to FSM instance |
| 352 | * \param[in] data Data to pass along with the event |
| 353 | * \returns 0 in case of success; negative on error |
| 354 | */ |
| 355 | int osmo_fsm_inst_dispatch(struct osmo_fsm_inst *fi, uint32_t event, void *data) |
| 356 | { |
| 357 | struct osmo_fsm *fsm; |
| 358 | const struct osmo_fsm_state *fs; |
| 359 | |
| 360 | if (!fi) { |
| 361 | LOGP(DLGLOBAL, LOGL_ERROR, "Trying to dispatch event %u to " |
| 362 | "non-existing FSM Instance!\n", event); |
| 363 | osmo_log_backtrace(DLGLOBAL, LOGL_ERROR); |
| 364 | return -ENODEV; |
| 365 | } |
| 366 | |
| 367 | fsm = fi->fsm; |
| 368 | OSMO_ASSERT(fi->state < fsm->num_states); |
| 369 | fs = &fi->fsm->states[fi->state]; |
| 370 | |
| 371 | LOGPFSM(fi, "Received Event %s\n", osmo_fsm_event_name(fsm, event)); |
| 372 | |
| 373 | if (((1 << event) & fsm->allstate_event_mask) && fsm->allstate_action) { |
| 374 | fsm->allstate_action(fi, event, data); |
| 375 | return 0; |
| 376 | } |
| 377 | |
| 378 | if (!((1 << event) & fs->in_event_mask)) { |
| 379 | LOGP(fsm->log_subsys, LOGL_ERROR, "%s(%s): Event %s not " |
| 380 | "permitted\n", osmo_fsm_inst_name(fi), |
| 381 | osmo_fsm_state_name(fsm, fi->state), |
| 382 | osmo_fsm_event_name(fsm, event)); |
| 383 | return -1; |
| 384 | } |
| 385 | fs->action(fi, event, data); |
| 386 | |
| 387 | return 0; |
| 388 | } |
| 389 | |
| 390 | /*! \brief Terminate FSM instance with given cause |
| 391 | * |
| 392 | * This safely terminates the given FSM instance by first iterating |
| 393 | * over all children and sending them a termination event. Next, it |
| 394 | * calls the FSM descriptors cleanup function (if any), followed by |
| 395 | * releasing any memory associated with the FSM instance. |
| 396 | * |
| 397 | * Finally, the parent FSM instance (if any) is notified using the |
| 398 | * parent termination event configured at time of FSM instance start. |
| 399 | * |
| 400 | * \param[in] fi FSM instance to be terminated |
| 401 | * \param[in] cause Cause / reason for termination |
| 402 | * \param[in] data Opaqueevent data to be passed to parent |
| 403 | */ |
| 404 | void osmo_fsm_inst_term(struct osmo_fsm_inst *fi, |
| 405 | enum osmo_fsm_term_cause cause, void *data) |
| 406 | { |
| 407 | struct osmo_fsm_inst *child, *child2; |
| 408 | struct osmo_fsm_inst *parent = fi->proc.parent; |
| 409 | uint32_t parent_term_event = fi->proc.parent_term_event; |
| 410 | |
| 411 | LOGPFSM(fi, "Terminating (cause = %u)\n", cause); |
| 412 | |
| 413 | /* iterate over all children */ |
| 414 | llist_for_each_entry_safe(child, child2, &fi->proc.children, proc.child) { |
| 415 | /* terminate child */ |
| 416 | osmo_fsm_inst_term(child, OSMO_FSM_TERM_PARENT, NULL); |
| 417 | } |
| 418 | |
| 419 | /* delete ourselves from the parent */ |
| 420 | llist_del(&fi->proc.child); |
| 421 | |
| 422 | /* call destructor / clean-up function */ |
| 423 | if (fi->fsm->cleanup) |
| 424 | fi->fsm->cleanup(fi, cause); |
| 425 | |
| 426 | LOGPFSM(fi, "Release\n"); |
| 427 | osmo_fsm_inst_free(fi); |
| 428 | |
| 429 | /* indicate our termination to the parent */ |
| 430 | if (parent && cause != OSMO_FSM_TERM_PARENT) |
| 431 | osmo_fsm_inst_dispatch(parent, parent_term_event, data); |
| 432 | } |
| 433 | |
| 434 | /*! @} */ |