Implement spurious wakeup for ATOMIC_WAIT
[c11tester.git] / execution.cc
index 53b6bccf790df471600a8f555f1ed17249a72443..4b8461e8f678c38302e6551f1ec56ecdc69d11ac 100644 (file)
@@ -247,43 +247,50 @@ void ModelExecution::restore_last_seq_num()
  * @param thread The thread that we might wake up
  * @return True, if we should wake up the sleeping thread; false otherwise
  */
-bool ModelExecution::should_wake_up(const ModelAction *curr, const Thread *thread) const
+bool ModelExecution::should_wake_up(const Thread *thread) const
 {
        const ModelAction *asleep = thread->get_pending();
-       /* Don't allow partial RMW to wake anyone up */
-       if (curr->is_rmwr())
-               return false;
-       /* Synchronizing actions may have been backtracked */
-       if (asleep->could_synchronize_with(curr))
-               return true;
-       /* All acquire/release fences and fence-acquire/store-release */
-       if (asleep->is_fence() && asleep->is_acquire() && curr->is_release())
-               return true;
-       /* Fence-release + store can awake load-acquire on the same location */
-       if (asleep->is_read() && asleep->is_acquire() && curr->same_var(asleep) && curr->is_write()) {
-               ModelAction *fence_release = get_last_fence_release(curr->get_tid());
-               if (fence_release && *(get_last_action(thread->get_id())) < *fence_release)
-                       return true;
-       }
+
        /* The sleep is literally sleeping */
-       if (asleep->is_sleep()) {
-               if (fuzzer->shouldWake(asleep))
-                       return true;
+       switch (asleep->get_type()) {
+               case THREAD_SLEEP:
+                       if (fuzzer->shouldWake(asleep))
+                               return true;
+                       break;
+               case ATOMIC_WAIT:
+               case ATOMIC_TIMEDWAIT:
+                       if (fuzzer->waitShouldWakeUp(asleep))
+                               return true;
+                       break;
+               default:
+                       return false;
        }
 
        return false;
 }
 
-void ModelExecution::wake_up_sleeping_actions(ModelAction *curr)
+void ModelExecution::wake_up_sleeping_actions()
 {
        for (unsigned int i = 0;i < get_num_threads();i++) {
-               Thread *thr = get_thread(int_to_id(i));
-               if (scheduler->is_sleep_set(thr)) {
-                       if (should_wake_up(curr, thr)) {
+               thread_id_t tid = int_to_id(i);
+               if (scheduler->is_sleep_set(tid)) {
+                       Thread *thr = get_thread(tid);
+                       if (should_wake_up(thr)) {
                                /* Remove this thread from sleep set */
                                scheduler->remove_sleep(thr);
-                               if (thr->get_pending()->is_sleep())
+                               ModelAction * pending = thr->get_pending();
+                               if (pending->is_sleep()) {
                                        thr->set_wakeup_state(true);
+                               } else if (pending->is_wait()) {
+                                       thr->set_wakeup_state(true);
+                                       simple_action_list_t *waiters = get_safe_ptr_action(&condvar_waiters_map, pending->get_location());
+                                       for (sllnode<ModelAction *> * rit = waiters->begin();rit != NULL;rit=rit->getNext()) {
+                                               if (rit->getVal()->get_tid() == tid) {
+                                                       waiters->erase(rit);
+                                                       break;
+                                               }
+                                       }
+                               }
                        }
                }
        }
@@ -419,10 +426,10 @@ bool ModelExecution::process_read(ModelAction *curr, SnapVector<ModelAction *> *
                                mo_graph->addEdge((*priorset)[i], rf);
                        }
                        read_from(curr, rf);
-                       get_thread(curr)->set_return_value(curr->get_return_value());
+                       get_thread(curr)->set_return_value(rf->get_write_value());
                        delete priorset;
                        //Update acquire fence clock vector
-                       ClockVector * hbcv = get_hb_from_write(curr->get_reads_from());
+                       ClockVector * hbcv = get_hb_from_write(rf);
                        if (hbcv != NULL)
                                get_thread(curr)->get_acq_fence_cv()->merge(hbcv);
                        return canprune && (curr->get_type() == ATOMIC_READ);
@@ -484,32 +491,26 @@ bool ModelExecution::process_mutex(ModelAction *curr)
                break;
        }
        case ATOMIC_WAIT: {
-               //TODO: DOESN'T REALLY IMPLEMENT SPURIOUS WAKEUPS CORRECTLY
-               if (fuzzer->shouldWait(curr)) {
-                       /* 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);
-                       }
+               Thread *curr_thrd = get_thread(curr);
+               /* wake up the other threads */
+               for (unsigned int i = 0;i < get_num_threads();i++) {
+                       Thread *t = get_thread(int_to_id(i));
+                       if (t->waiting_on() == curr_thrd && t->get_pending()->is_lock())
+                               scheduler->wake(t);
+               }
 
-                       /* unlock the lock - after checking who was waiting on it */
-                       state->locked = NULL;
+               /* unlock the lock - after checking who was waiting on it */
+               state->locked = NULL;
 
-                       /* remove old wait action and disable this thread */
-                       simple_action_list_t * waiters = get_safe_ptr_action(&condvar_waiters_map, curr->get_location());
-                       for (sllnode<ModelAction *> * it = waiters->begin();it != NULL;it = it->getNext()) {
-                               ModelAction * wait = it->getVal();
-                               if (wait->get_tid() == curr->get_tid()) {
-                                       waiters->erase(it);
-                                       break;
-                               }
-                       }
+               /* disable this thread */
+               simple_action_list_t * waiters = get_safe_ptr_action(&condvar_waiters_map, curr->get_location());
+               waiters->push_back(curr);
+               curr_thrd->set_pending(curr);   // Forbid this thread to stash a new action
 
-                       waiters->push_back(curr);
-                       scheduler->sleep(get_thread(curr));
-               }
+               if (fuzzer->waitShouldFail(curr))
+                       scheduler->add_sleep(curr_thrd);        // Place this thread into THREAD_SLEEP_SET
+               else
+                       scheduler->sleep(curr_thrd);
 
                break;
        }
@@ -526,9 +527,9 @@ bool ModelExecution::process_mutex(ModelAction *curr)
 
                // TODO: lock count for recursive mutexes
                /* wake up the other threads */
+               Thread *curr_thrd = get_thread(curr);
                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);
                }
@@ -541,7 +542,10 @@ bool ModelExecution::process_mutex(ModelAction *curr)
                simple_action_list_t *waiters = get_safe_ptr_action(&condvar_waiters_map, curr->get_location());
                //activate all the waiting threads
                for (sllnode<ModelAction *> * rit = waiters->begin();rit != NULL;rit=rit->getNext()) {
-                       scheduler->wake(get_thread(rit->getVal()));
+                       Thread * thread = get_thread(rit->getVal());
+                       if (thread->get_state() != THREAD_COMPLETED)
+                               scheduler->wake(thread);
+                       thread->set_wakeup_state(true);
                }
                waiters->clear();
                break;
@@ -550,7 +554,9 @@ bool ModelExecution::process_mutex(ModelAction *curr)
                simple_action_list_t *waiters = get_safe_ptr_action(&condvar_waiters_map, curr->get_location());
                if (waiters->size() != 0) {
                        Thread * thread = fuzzer->selectNotify(waiters);
-                       scheduler->wake(thread);
+                       if (thread->get_state() != THREAD_COMPLETED)
+                               scheduler->wake(thread);
+                       thread->set_wakeup_state(true);
                }
                break;
        }
@@ -769,7 +775,8 @@ bool ModelExecution::synchronize(const ModelAction *first, ModelAction *second)
  * @return a bool that indicates whether the action is enabled.
  */
 bool ModelExecution::check_action_enabled(ModelAction *curr) {
-       if (curr->is_lock()) {
+       switch (curr->get_type()) {
+       case ATOMIC_LOCK: {
                cdsc::mutex *lock = curr->get_mutex();
                struct cdsc::mutex_state *state = lock->get_state();
                if (state->locked) {
@@ -781,14 +788,23 @@ bool ModelExecution::check_action_enabled(ModelAction *curr) {
 
                        return false;
                }
-       } else if (curr->is_thread_join()) {
+               break;
+       }
+       case THREAD_JOIN:
+       case PTHREAD_JOIN: {
                Thread *blocking = curr->get_thread_operand();
                if (!blocking->is_complete()) {
                        return false;
                }
-       } else if (curr->is_sleep()) {
+               break;
+       }
+       case THREAD_SLEEP: {
                if (!fuzzer->shouldSleep(curr))
                        return false;
+               break;
+       }
+       default:
+               return true;
        }
 
        return true;
@@ -808,28 +824,24 @@ bool ModelExecution::check_action_enabled(ModelAction *curr) {
 ModelAction * ModelExecution::check_current_action(ModelAction *curr)
 {
        ASSERT(curr);
-       bool second_part_of_rmw = curr->is_rmwc() || curr->is_rmw();
        bool newly_explored = initialize_curr_action(&curr);
 
        DBG();
 
-       wake_up_sleeping_actions(curr);
+       wake_up_sleeping_actions();
 
        SnapVector<ModelAction *> * rf_set = NULL;
+       bool canprune = false;
        /* Build may_read_from set for newly-created actions */
-       if (newly_explored && curr->is_read())
+       if (curr->is_read() && newly_explored) {
                rf_set = build_may_read_from(curr);
-
-       bool canprune = false;
-
-       if (curr->is_read() && !second_part_of_rmw) {
                canprune = process_read(curr, rf_set);
                delete rf_set;
        } else
                ASSERT(rf_set == NULL);
 
-       /* Add the action to lists */
-       if (!second_part_of_rmw) {
+       /* Add the action to lists if not the second part of a rmw */
+       if (newly_explored) {
 #ifdef COLLECT_STAT
                record_atomic_stats(curr);
 #endif
@@ -884,7 +896,7 @@ ModelAction * ModelExecution::process_rmw(ModelAction *act) {
  */
 
 bool ModelExecution::r_modification_order(ModelAction *curr, const ModelAction *rf,
-                                                                                                                                                                       SnapVector<ModelAction *> * priorset, bool * canprune, bool check_only)
+                                                                                                                                                                       SnapVector<ModelAction *> * priorset, bool * canprune)
 {
        SnapVector<action_list_t> *thrd_lists = obj_thrd_map.get(curr->get_location());
        ASSERT(curr->is_read());
@@ -947,8 +959,7 @@ bool ModelExecution::r_modification_order(ModelAction *curr, const ModelAction *
                                                *act < *last_sc_fence_thread_local) {
                                        if (mo_graph->checkReachable(rf, act))
                                                return false;
-                                       if (!check_only)
-                                               priorset->push_back(act);
+                                       priorset->push_back(act);
                                        break;
                                }
                                /* C++, Section 29.3 statement 4 */
@@ -956,8 +967,7 @@ bool ModelExecution::r_modification_order(ModelAction *curr, const ModelAction *
                                                                 *act < *last_sc_fence_local) {
                                        if (mo_graph->checkReachable(rf, act))
                                                return false;
-                                       if (!check_only)
-                                               priorset->push_back(act);
+                                       priorset->push_back(act);
                                        break;
                                }
                                /* C++, Section 29.3 statement 6 */
@@ -965,8 +975,7 @@ bool ModelExecution::r_modification_order(ModelAction *curr, const ModelAction *
                                                                 *act < *last_sc_fence_thread_before) {
                                        if (mo_graph->checkReachable(rf, act))
                                                return false;
-                                       if (!check_only)
-                                               priorset->push_back(act);
+                                       priorset->push_back(act);
                                        break;
                                }
                        }
@@ -985,20 +994,17 @@ bool ModelExecution::r_modification_order(ModelAction *curr, const ModelAction *
                                if (act->is_write()) {
                                        if (mo_graph->checkReachable(rf, act))
                                                return false;
-                                       if (!check_only)
-                                               priorset->push_back(act);
+                                       priorset->push_back(act);
                                } else {
                                        ModelAction *prevrf = act->get_reads_from();
                                        if (!prevrf->equals(rf)) {
                                                if (mo_graph->checkReachable(rf, prevrf))
                                                        return false;
-                                               if (!check_only)
-                                                       priorset->push_back(prevrf);
+                                               priorset->push_back(prevrf);
                                        } else {
                                                if (act->get_tid() == curr->get_tid()) {
                                                        //Can prune curr from obj list
-                                                       if (!check_only)
-                                                               *canprune = true;
+                                                       *canprune = true;
                                                }
                                        }
                                }
@@ -1120,43 +1126,6 @@ void ModelExecution::w_modification_order(ModelAction *curr)
 
 }
 
-/**
- * Arbitrary reads from the future are not allowed. Section 29.3 part 9 places
- * some constraints. This method checks one the following constraint (others
- * require compiler support):
- *
- *   If X --hb-> Y --mo-> Z, then X should not read from Z.
- *   If X --hb-> Y, A --rf-> Y, and A --mo-> Z, then X should not read from Z.
- */
-bool ModelExecution::mo_may_allow(const ModelAction *writer, const ModelAction *reader)
-{
-       SnapVector<action_list_t> *thrd_lists = obj_thrd_map.get(reader->get_location());
-       unsigned int i;
-       /* Iterate over all threads */
-       for (i = 0;i < thrd_lists->size();i++) {
-               const ModelAction *write_after_read = NULL;
-
-               /* Iterate over actions in thread, starting from most recent */
-               action_list_t *list = &(*thrd_lists)[i];
-               sllnode<ModelAction *>* rit;
-               for (rit = list->end();rit != NULL;rit=rit->getPrev()) {
-                       ModelAction *act = rit->getVal();
-
-                       /* Don't disallow due to act == reader */
-                       if (!reader->happens_before(act) || reader == act)
-                               break;
-                       else if (act->is_write())
-                               write_after_read = act;
-                       else if (act->is_read() && act->get_reads_from() != NULL)
-                               write_after_read = act->get_reads_from();
-               }
-
-               if (write_after_read && write_after_read != writer && mo_graph->checkReachable(write_after_read, writer))
-                       return false;
-       }
-       return true;
-}
-
 /**
  * Computes the clock vector that happens before propagates from this write.
  *
@@ -1819,7 +1788,7 @@ ClockVector * ModelExecution::computeMinimalCV() {
        //Thread 0 isn't a real thread, so skip it..
        for(unsigned int i = 1;i < thread_map.size();i++) {
                Thread * t = thread_map[i];
-               if (t->get_state() == THREAD_COMPLETED)
+               if (t->is_complete())
                        continue;
                thread_id_t tid = int_to_id(i);
                ClockVector * cv = get_cv(tid);