X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=model.cc;h=811d81a627b00357d8dc598ad16dcae4bc6911e9;hb=d1e11baca91adc67244597858f1b63abfb1d5507;hp=a03ea46224f1d7a4d10f64927b9df9d385eeb21e;hpb=20994240335ce1d54fb6c4b2c8df684182f0a3f9;p=model-checker.git diff --git a/model.cc b/model.cc index a03ea46..811d81a 100644 --- a/model.cc +++ b/model.cc @@ -83,7 +83,6 @@ ModelChecker::ModelChecker(struct model_params params) : action_trace(new action_list_t()), thread_map(new HashTable()), obj_map(new HashTable()), - lock_waiters_map(new HashTable()), condvar_waiters_map(new HashTable()), obj_thrd_map(new HashTable *, uintptr_t, 4 >()), promises(new SnapVector()), @@ -109,7 +108,6 @@ ModelChecker::~ModelChecker() delete obj_thrd_map; delete obj_map; - delete lock_waiters_map; delete condvar_waiters_map; delete action_trace; @@ -260,20 +258,8 @@ Thread * ModelChecker::get_next_thread() scheduler->update_sleep_set(prevnode); /* Reached divergence point */ - if (nextnode->increment_misc()) { - /* The next node will try to satisfy a different misc_index values. */ - tid = next->get_tid(); - node_stack->pop_restofstack(2); - } else if (nextnode->increment_promise()) { - /* The next node will try to satisfy a different set of promises. */ - tid = next->get_tid(); - node_stack->pop_restofstack(2); - } else if (nextnode->increment_read_from()) { - /* The next node will read from a different value. */ - tid = next->get_tid(); - node_stack->pop_restofstack(2); - } else if (nextnode->increment_relseq_break()) { - /* The next node will try to resolve a release sequence differently */ + if (nextnode->increment_behaviors()) { + /* Execute the same thread with a new behavior */ tid = next->get_tid(); node_stack->pop_restofstack(2); } else { @@ -409,22 +395,6 @@ bool ModelChecker::is_deadlocked() const return blocking_threads; } -/** - * Check if a Thread has entered a circular wait deadlock situation. This will - * not check other threads for potential deadlock situations, and may miss - * deadlocks involving WAIT. - * - * @param t The thread which may have entered a deadlock - * @return True if this Thread entered a deadlock; false otherwise - */ -bool ModelChecker::is_circular_wait(const Thread *t) const -{ - for (Thread *waiting = t->waiting_on() ; waiting != NULL; waiting = waiting->waiting_on()) - if (waiting == t) - return true; - return false; -} - /** * Check if this is a complete execution. That is, have all thread completed * execution (rather than exiting because sleep sets have forced a redundant @@ -996,32 +966,26 @@ bool ModelChecker::process_mutex(ModelAction *curr) } break; } + case ATOMIC_WAIT: case ATOMIC_UNLOCK: { - //unlock the lock - state->locked = NULL; - //wake up the other threads - action_list_t *waiters = get_safe_ptr_action(lock_waiters_map, curr->get_location()); - //activate all the waiting threads - for (action_list_t::iterator rit = waiters->begin(); rit != waiters->end(); rit++) { - scheduler->wake(get_thread(*rit)); + /* wake up the other threads */ + for (unsigned int i = 0; i < get_num_threads(); i++) { + Thread *t = get_thread(int_to_id(i)); + Thread *curr_thrd = get_thread(curr); + if (t->waiting_on() == curr_thrd && t->get_pending()->is_lock()) + scheduler->wake(t); } - waiters->clear(); - break; - } - case ATOMIC_WAIT: { - //unlock the lock + + /* unlock the lock - after checking who was waiting on it */ state->locked = NULL; - //wake up the other threads - action_list_t *waiters = get_safe_ptr_action(lock_waiters_map, (void *) curr->get_value()); - //activate all the waiting threads - for (action_list_t::iterator rit = waiters->begin(); rit != waiters->end(); rit++) { - scheduler->wake(get_thread(*rit)); - } - waiters->clear(); - //check whether we should go to sleep or not...simulate spurious failures + + if (!curr->is_wait()) + break; /* The rest is only for ATOMIC_WAIT */ + + /* Should we go to sleep? (simulate spurious failures) */ if (curr->get_node()->get_misc() == 0) { get_safe_ptr_action(condvar_waiters_map, curr->get_location())->push_back(curr); - //disable us + /* disable us */ scheduler->sleep(get_thread(curr)); } break; @@ -1051,25 +1015,66 @@ bool ModelChecker::process_mutex(ModelAction *curr) return false; } +/** + * @brief Check if the current pending promises allow a future value to be sent + * + * If one of the following is true: + * (a) there are no pending promises + * (b) the reader and writer do not cross any promises + * Then, it is safe to pass a future value back now. + * + * Otherwise, we must save the pending future value until (a) or (b) is true + * + * @param writer The operation which sends the future value. Must be a write. + * @param reader The operation which will observe the value. Must be a read. + * @return True if the future value can be sent now; false if it must wait. + */ +bool ModelChecker::promises_may_allow(const ModelAction *writer, + const ModelAction *reader) const +{ + if (promises->empty()) + return true; + for(int i=promises->size()-1;i>=0;i--) { + ModelAction *pr=(*promises)[i]->get_reader(0); + //reader is after promise...doesn't cross any promise + if (*reader > *pr) + return true; + //writer is after promise, reader before...bad... + if (*writer > *pr) + return false; + } + return true; +} + +/** + * @brief Add a future value to a reader + * + * This function performs a few additional checks to ensure that the future + * value can be feasibly observed by the reader + * + * @param writer The operation whose value is sent. Must be a write. + * @param reader The read operation which may read the future value. Must be a read. + */ void ModelChecker::add_future_value(const ModelAction *writer, ModelAction *reader) { /* Do more ambitious checks now that mo is more complete */ - if (mo_may_allow(writer, reader)) { - Node *node = reader->get_node(); - - /* Find an ancestor thread which exists at the time of the reader */ - Thread *write_thread = get_thread(writer); - while (id_to_int(write_thread->get_id()) >= node->get_num_threads()) - write_thread = write_thread->get_parent(); - - struct future_value fv = { - writer->get_write_value(), - writer->get_seq_number() + params.maxfuturedelay, - write_thread->get_id(), - }; - if (node->add_future_value(fv)) - set_latest_backtrack(reader); - } + if (!mo_may_allow(writer, reader)) + return; + + Node *node = reader->get_node(); + + /* Find an ancestor thread which exists at the time of the reader */ + Thread *write_thread = get_thread(writer); + while (id_to_int(write_thread->get_id()) >= node->get_num_threads()) + write_thread = write_thread->get_parent(); + + struct future_value fv = { + writer->get_write_value(), + writer->get_seq_number() + params.maxfuturedelay, + write_thread->get_id(), + }; + if (node->add_future_value(fv)) + set_latest_backtrack(reader); } /** @@ -1082,30 +1087,39 @@ bool ModelChecker::process_write(ModelAction *curr) /* Readers to which we may send our future value */ ModelVector send_fv; - bool updated_mod_order = w_modification_order(curr, &send_fv); - int promise_idx = get_promise_to_resolve(curr); const ModelAction *earliest_promise_reader; bool updated_promises = false; - if (promise_idx >= 0) { - earliest_promise_reader = (*promises)[promise_idx]->get_reader(0); - updated_promises = resolve_promise(curr, promise_idx); + bool updated_mod_order = w_modification_order(curr, &send_fv); + Promise *promise = pop_promise_to_resolve(curr); + + if (promise) { + earliest_promise_reader = promise->get_reader(0); + updated_promises = resolve_promise(curr, promise); } else earliest_promise_reader = NULL; - /* Don't send future values to reads after the Promise we resolve */ for (unsigned int i = 0; i < send_fv.size(); i++) { ModelAction *read = send_fv[i]; - if (!earliest_promise_reader || *read < *earliest_promise_reader) - futurevalues->push_back(PendingFutureValue(curr, read)); + + /* Don't send future values to reads after the Promise we resolve */ + if (!earliest_promise_reader || *read < *earliest_promise_reader) { + /* Check if future value can be sent immediately */ + if (promises_may_allow(curr, read)) { + add_future_value(curr, read); + } else { + futurevalues->push_back(PendingFutureValue(curr, read)); + } + } } - if (promises->size() == 0) { - for (unsigned int i = 0; i < futurevalues->size(); i++) { - struct PendingFutureValue pfv = (*futurevalues)[i]; - add_future_value(pfv.writer, pfv.act); + /* Check the pending future values */ + for (int i = (int)futurevalues->size() - 1; i >= 0; i--) { + struct PendingFutureValue pfv = (*futurevalues)[i]; + if (promises_may_allow(pfv.writer, pfv.reader)) { + add_future_value(pfv.writer, pfv.reader); + futurevalues->erase(futurevalues->begin() + i); } - futurevalues->clear(); } mo_graph->commitChanges(); @@ -1128,6 +1142,7 @@ bool ModelChecker::process_fence(ModelAction *curr) * use in later synchronization * fence-acquire (this function): search for hypothetical release * sequences + * fence-seq-cst: MO constraints formed in {r,w}_modification_order */ bool updated = false; if (curr->is_acquire()) { @@ -1444,12 +1459,9 @@ bool ModelChecker::check_action_enabled(ModelAction *curr) { if (curr->is_lock()) { std::mutex *lock = (std::mutex *)curr->get_location(); struct std::mutex_state *state = lock->get_state(); - if (state->locked) { - //Stick the action in the appropriate waiting queue - get_safe_ptr_action(lock_waiters_map, curr->get_location())->push_back(curr); + if (state->locked) return false; - } - } else if (curr->get_type() == THREAD_JOIN) { + } else if (curr->is_thread_join()) { Thread *blocking = (Thread *)curr->get_location(); if (!blocking->is_complete()) { blocking->push_wait_list(curr); @@ -1812,6 +1824,9 @@ bool ModelChecker::r_modification_order(ModelAction *curr, const rf_type *rf) /* Last SC fence in the current thread */ ModelAction *last_sc_fence_local = get_last_seq_cst_fence(curr->get_tid(), NULL); + ModelAction *last_sc_write = NULL; + if (curr->is_seqcst()) + last_sc_write = get_last_seq_cst_write(curr); /* Iterate over all threads */ for (i = 0; i < thrd_lists->size(); i++) { @@ -1863,6 +1878,12 @@ bool ModelChecker::r_modification_order(ModelAction *curr, const rf_type *rf) } } + /* C++, Section 29.3 statement 3 (second subpoint) */ + if (curr->is_seqcst() && last_sc_write && act == last_sc_write) { + added = mo_graph->addEdge(act, rf) || added; + break; + } + /* * Include at most one act per-thread that "happens * before" curr @@ -2038,7 +2059,7 @@ bool ModelChecker::w_modification_order(ModelAction *curr, ModelVectoris_rmw()) return true; @@ -2463,8 +2484,11 @@ ModelAction * ModelChecker::get_last_seq_cst_write(ModelAction *curr) const action_list_t *list = get_safe_ptr_action(obj_map, location); /* Find: max({i in dom(S) | seq_cst(t_i) && isWrite(t_i) && samevar(t_i, t)}) */ action_list_t::reverse_iterator rit; - for (rit = list->rbegin(); rit != list->rend(); rit++) - if ((*rit)->is_write() && (*rit)->is_seqcst() && (*rit) != curr) + for (rit = list->rbegin(); (*rit) != curr; rit++) + ; + rit++; /* Skip past curr */ + for ( ; rit != list->rend(); rit++) + if ((*rit)->is_write() && (*rit)->is_seqcst()) return *rit; return NULL; } @@ -2537,29 +2561,31 @@ ClockVector * ModelChecker::get_cv(thread_id_t tid) const } /** - * @brief Find the promise, if any to resolve for the current action + * @brief Find the promise (if any) to resolve for the current action and + * remove it from the pending promise vector * @param curr The current ModelAction. Should be a write. - * @return The (non-negative) index for the Promise to resolve, if any; - * otherwise -1 + * @return The Promise to resolve, if any; otherwise NULL */ -int ModelChecker::get_promise_to_resolve(const ModelAction *curr) const +Promise * ModelChecker::pop_promise_to_resolve(const ModelAction *curr) { for (unsigned int i = 0; i < promises->size(); i++) - if (curr->get_node()->get_promise(i)) - return i; - return -1; + if (curr->get_node()->get_promise(i)) { + Promise *ret = (*promises)[i]; + promises->erase(promises->begin() + i); + return ret; + } + return NULL; } /** * Resolve a Promise with a current write. * @param write The ModelAction that is fulfilling Promises - * @param promise_idx The index corresponding to the promise + * @param promise The Promise to resolve * @return True if the Promise was successfully resolved; false otherwise */ -bool ModelChecker::resolve_promise(ModelAction *write, unsigned int promise_idx) +bool ModelChecker::resolve_promise(ModelAction *write, Promise *promise) { ModelVector actions_to_check; - Promise *promise = (*promises)[promise_idx]; for (unsigned int i = 0; i < promise->get_num_readers(); i++) { ModelAction *read = promise->get_reader(i); @@ -2571,7 +2597,6 @@ bool ModelChecker::resolve_promise(ModelAction *write, unsigned int promise_idx) if (!mo_graph->resolvePromise(promise, write)) priv->failed_promise = true; - promises->erase(promises->begin() + promise_idx); /** * @todo It is possible to end up in an inconsistent state, where a * "resolved" promise may still be referenced if @@ -3105,7 +3130,7 @@ void ModelChecker::run() Thread *thr = get_thread(tid); if (!thr->is_model_thread() && !thr->is_complete() && !thr->get_pending()) { switch_from_master(thr); - if (is_circular_wait(thr)) + if (thr->is_waiting_on(thr)) assert_bug("Deadlock detected"); } }