X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=model.cc;h=8e513a3a47c972d70b0e9c3c6a9d72ba3e867171;hb=fa36db2da01d7da10e0cd375fda3c2db4ce3a05b;hp=38d08d988e198e37a5f136a1b44988892ee4c3d7;hpb=443fd91df4ad9b88d5ec88a29f80008911b4a917;p=model-checker.git diff --git a/model.cc b/model.cc index 38d08d9..8e513a3 100644 --- a/model.cc +++ b/model.cc @@ -204,34 +204,43 @@ Node * ModelChecker::get_curr_node() const return node_stack->get_head(); } +/** + * @brief Select the next thread to execute based on the curren action + * + * RMW actions occur in two parts, and we cannot split them. And THREAD_CREATE + * actions should be followed by the execution of their child thread. In either + * case, the current action should determine the next thread schedule. + * + * @param curr The current action + * @return The next thread to run, if the current action will determine this + * selection; otherwise NULL + */ +Thread * ModelChecker::action_select_next_thread(const ModelAction *curr) const +{ + /* Do not split atomic RMW */ + if (curr->is_rmwr()) + return get_thread(curr); + /* Follow CREATE with the created thread */ + if (curr->get_type() == THREAD_CREATE) + return curr->get_thread_operand(); + return NULL; +} + /** * @brief Choose the next thread to execute. * - * This function chooses the next thread that should execute. It can force the - * adjacency of read/write portions of a RMW action, force THREAD_CREATE to be - * followed by a THREAD_START, or it can enforce execution replay/backtracking. - * The model-checker may have no preference regarding the next thread (i.e., - * when exploring a new execution ordering), in which case we defer to the - * scheduler. + * This function chooses the next thread that should execute. It can enforce + * execution replay/backtracking or, if the model-checker has no preference + * regarding the next thread (i.e., when exploring a new execution ordering), + * we defer to the scheduler. * - * @param curr Optional: The current ModelAction. Only used if non-NULL and it - * might guide the choice of next thread (i.e., THREAD_CREATE should be - * followed by THREAD_START, or ATOMIC_RMWR followed by ATOMIC_{RMW,RMWC}) - * @return The next chosen thread to run, if any exist. Or else if no threads - * remain to be executed, return NULL. + * @return The next chosen thread to run, if any exist. Or else if the current + * execution should terminate, return NULL. */ -Thread * ModelChecker::get_next_thread(ModelAction *curr) +Thread * ModelChecker::get_next_thread() { thread_id_t tid; - if (curr != NULL) { - /* Do not split atomic actions. */ - if (curr->is_rmwr()) - return get_thread(curr); - else if (curr->get_type() == THREAD_CREATE) - return curr->get_thread_operand(); - } - /* * Have we completed exploring the preselected path? Then let the * scheduler decide @@ -400,6 +409,22 @@ 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 @@ -514,7 +539,7 @@ void ModelChecker::print_execution(bool printbugs) const { print_program_output(); - if (DBG_ENABLED() || params.verbose) { + if (params.verbose) { model_print("Earliest divergence point since last feasible execution:\n"); if (earliest_diverge) earliest_diverge->print(); @@ -558,7 +583,7 @@ bool ModelChecker::next_execution() record_stats(); /* Output */ - if (DBG_ENABLED() || params.verbose || (complete && have_bug_reports())) + if (params.verbose || (complete && have_bug_reports())) print_execution(complete); else clear_program_output(); @@ -797,6 +822,21 @@ void ModelChecker::set_backtracking(ModelAction *act) if (unfair) continue; } + + /* See if CHESS-like yield fairness allows */ + if (model->params.yieldon) { + bool unfair = false; + for (int t = 0; t < node->get_num_threads(); t++) { + thread_id_t tother = int_to_id(t); + if (node->is_enabled(tother) && node->has_priority_over(tid, tother)) { + unfair = true; + break; + } + } + if (unfair) + continue; + } + /* Cache the latest backtracking point */ set_latest_backtrack(prev); @@ -853,7 +893,6 @@ ModelAction * ModelChecker::get_next_backtrack() bool ModelChecker::process_read(ModelAction *curr) { Node *node = curr->get_node(); - uint64_t value = VALUE_NONE; while (true) { bool updated = false; switch (node->get_read_from_status()) { @@ -874,7 +913,6 @@ bool ModelChecker::process_read(ModelAction *curr) } updated = r_modification_order(curr, rf); - value = rf->get_value(); read_from(curr, rf); mo_graph->commitChanges(); mo_check_promises(curr, true); @@ -884,7 +922,6 @@ bool ModelChecker::process_read(ModelAction *curr) Promise *promise = curr->get_node()->get_read_from_promise(); if (promise->add_reader(curr)) priv->failed_promise = true; - value = promise->get_value(); curr->set_read_from_promise(promise); mo_graph->startChanges(); if (!check_recency(curr, promise)) @@ -897,7 +934,6 @@ bool ModelChecker::process_read(ModelAction *curr) /* Read from future value */ struct future_value fv = node->get_future_value(); Promise *promise = new Promise(curr, fv); - value = fv.value; curr->set_read_from_promise(promise); promises->push_back(promise); mo_graph->startChanges(); @@ -908,7 +944,7 @@ bool ModelChecker::process_read(ModelAction *curr) default: ASSERT(false); } - get_thread(curr)->set_return_value(value); + get_thread(curr)->set_return_value(curr->get_return_value()); return updated; } } @@ -931,20 +967,15 @@ bool ModelChecker::process_read(ModelAction *curr) */ bool ModelChecker::process_mutex(ModelAction *curr) { - std::mutex *mutex = NULL; + std::mutex *mutex = curr->get_mutex(); struct std::mutex_state *state = NULL; - if (curr->is_trylock() || curr->is_lock() || curr->is_unlock()) { - mutex = (std::mutex *)curr->get_location(); - state = mutex->get_state(); - } else if (curr->is_wait()) { - mutex = (std::mutex *)curr->get_value(); + if (mutex) state = mutex->get_state(); - } switch (curr->get_type()) { case ATOMIC_TRYLOCK: { - bool success = !state->islocked; + bool success = !state->locked; curr->set_try_lock(success); if (!success) { get_thread(curr)->set_return_value(0); @@ -956,7 +987,7 @@ bool ModelChecker::process_mutex(ModelAction *curr) case ATOMIC_LOCK: { if (curr->get_cv()->getClock(state->alloc_tid) <= state->alloc_clock) assert_bug("Lock access before initialization"); - state->islocked = true; + state->locked = get_thread(curr); ModelAction *unlock = get_last_unlock(curr); //synchronize with the previous unlock statement if (unlock != NULL) { @@ -967,7 +998,7 @@ bool ModelChecker::process_mutex(ModelAction *curr) } case ATOMIC_UNLOCK: { //unlock the lock - state->islocked = false; + 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 @@ -979,7 +1010,7 @@ bool ModelChecker::process_mutex(ModelAction *curr) } case ATOMIC_WAIT: { //unlock the lock - state->islocked = false; + 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 @@ -1411,7 +1442,7 @@ 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->islocked) { + if (state->locked) { //Stick the action in the appropriate waiting queue get_safe_ptr_action(lock_waiters_map, curr->get_location())->push_back(curr); return false; @@ -1460,6 +1491,11 @@ ModelAction * ModelChecker::check_current_action(ModelAction *curr) wake_up_sleeping_actions(curr); + /* Compute fairness information for CHESS yield algorithm */ + if (model->params.yieldon) { + curr->get_node()->update_yield(scheduler); + } + /* Add the action to lists before any other model-checking tasks */ if (!second_part_of_rmw) add_action_to_lists(curr); @@ -2865,6 +2901,14 @@ void ModelChecker::print_summary() const print_infeasibility(" INFEASIBLE"); print_list(action_trace); model_print("\n"); + if (!promises->empty()) { + model_print("Pending promises:\n"); + for (unsigned int i = 0; i < promises->size(); i++) { + model_print(" [P%u] ", i); + (*promises)[i]->print(); + } + model_print("\n"); + } } /** @@ -3011,7 +3055,11 @@ Thread * ModelChecker::take_step(ModelAction *curr) if (curr_thrd->is_blocked() || curr_thrd->is_complete()) scheduler->remove_thread(curr_thrd); - Thread *next_thrd = get_next_thread(curr); + Thread *next_thrd = NULL; + if (curr) + next_thrd = action_select_next_thread(curr); + if (!next_thrd) + next_thrd = get_next_thread(); DEBUG("(%d, %d)\n", curr_thrd ? id_to_int(curr_thrd->get_id()) : -1, next_thrd ? id_to_int(next_thrd->get_id()) : -1); @@ -3045,6 +3093,8 @@ 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)) + assert_bug("Deadlock detected"); } }