X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=model.cc;h=4a35fcd51ac965993c4194734107ddccbdae084b;hb=9580c5beb0b9e5425d77ddb142e18574d0dea16c;hp=780633e3e6a0d4ec0f0778c09cf3403c130175e8;hpb=4dd0204b6013e344a8728d27448cbf32f50825b6;p=model-checker.git diff --git a/model.cc b/model.cc index 780633e..4a35fcd 100644 --- a/model.cc +++ b/model.cc @@ -260,20 +260,8 @@ 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 +397,6 @@ 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 +968,25 @@ 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()); + action_list_t *waiters = get_safe_ptr_action(lock_waiters_map, mutex); //activate all the waiting threads for (action_list_t::iterator rit = waiters->begin(); rit != waiters->end(); rit++) { scheduler->wake(get_thread(*rit)); } waiters->clear(); - break; - } - case ATOMIC_WAIT: { - //unlock the lock - 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 +1016,66 @@ 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); } /** @@ -1094,19 +1100,27 @@ bool ModelChecker::process_write(ModelAction *curr) } 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->empty()) { - 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(); @@ -1451,7 +1465,7 @@ bool ModelChecker::check_action_enabled(ModelAction *curr) { get_safe_ptr_action(lock_waiters_map, curr->get_location())->push_back(curr); 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); @@ -2049,7 +2063,7 @@ bool ModelChecker::w_modification_order(ModelAction *curr, ModelVectoris_rmw()) return true; @@ -3120,7 +3134,7 @@ 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"); } }