threads: move circular wait check into Threads::is_waiting_on

[model-checker.git] / model.cc

diff --git a/model.cc b/model.cc
index 167ea947a79a020964ec13fc67d67077aae961f7..879f1dea17d162b38ca240e4c628043ed00001c3 100644 (file)
--- a/model.cc
+++ b/model.cc
@@ -409,22 +409,6 @@ 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
@@ -1056,7 +1040,7 @@ bool ModelChecker::process_mutex(ModelAction *curr)
  *
  * If one of the following is true:
  *  (a) there are no pending promises
- *  (b) the reader is ordered after the latest Promise creation
+ *  (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
@@ -1068,8 +1052,18 @@ bool ModelChecker::process_mutex(ModelAction *curr)
 bool ModelChecker::promises_may_allow(const ModelAction *writer,
                const ModelAction *reader) const
 {
-       return promises->empty() ||
-               *(promises->back()->get_reader(0)) < *reader;
+       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;
 }
 
 /**
@@ -3159,7 +3153,7 @@ 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");
                                }
                        }