X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;ds=sidebyside;f=model.cc;h=d15a094f7d8049e1a1e81ed8ac78527b6d1ca66a;hb=ed060a0d38302898816bedc7205d0283fffcc6f1;hp=7741760025162b786b48c903aaf86937bb4cb0f1;hpb=db5cad55a147218984ef544439ee8a936303ddf8;p=c11tester.git

diff --git a/model.cc b/model.cc
index 77417600..d15a094f 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();
@@ -935,7 +960,7 @@ bool ModelChecker::process_mutex(ModelAction *curr)
 
 	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);
@@ -947,7 +972,7 @@ 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) {
@@ -958,7 +983,7 @@ 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
@@ -970,7 +995,7 @@ 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
@@ -1402,7 +1427,7 @@ 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;
@@ -2856,6 +2881,14 @@ 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");
+	}
 }
 
 /**
@@ -3002,7 +3035,11 @@ 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);
@@ -3036,6 +3073,8 @@ 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");
 				}
 			}