''

1 files changed, 95 insertions, 89 deletions

diff --git a/ptw32_callUserDestroyRoutines.c b/ptw32_callUserDestroyRoutines.c
index cdec87e..a583f18 100644
--- a/ptw32_callUserDestroyRoutines.c
+++ b/ptw32_callUserDestroyRoutines.c
@@ -77,10 +77,6 @@ ptw32_callUserDestroyRoutines (pthread_t thread)
        * for the current thread.
        *
        * Do this process at most PTHREAD_DESTRUCTOR_ITERATIONS times.
-       *
-       * First we need to serialise with pthread_key_delete by locking
-       * both assoc guards, but in the reverse order to normal, and so
-       * we must be careful to avoid deadlock.
        */
       do
 	{
@@ -89,125 +85,135 @@ ptw32_callUserDestroyRoutines (pthread_t thread)
 
 	  (void) pthread_mutex_lock(&(sp->threadLock));
 	  /*
-	   * The next assoc pointer is stored in the thread struct so that
+	   * The pointer to the next assoc is stored in the thread struct so that
 	   * the assoc destructor in pthread_key_delete can adjust it
 	   * if it deletes this assoc. This can happen if we fail to acquire
 	   * both locks below, and are forced to release all of our locks,
-	   * leaving open the opportunity.
+	   * leaving open the opportunity for pthread_key_delete to get in
+	   * before us.
 	   */
 	  sp->nextAssoc = sp->keys;
 	  (void) pthread_mutex_unlock(&(sp->threadLock));
 
-      for (;;)
-	{
-	  void * value;
-	  pthread_key_t k;
-	  void (*destructor) (void *);
-
-	  (void) pthread_mutex_lock(&(sp->threadLock));
-
-	  if ((assoc = (ThreadKeyAssoc *)sp->nextAssoc) == NULL)
-	    {
-	      /* Finished */
-	      pthread_mutex_unlock(&(sp->threadLock));
-	      break;
-	    }
-	  else
+	  for (;;)
 	    {
+	      void * value;
+	      pthread_key_t k;
+	      void (*destructor) (void *);
+
 	      /*
-	       * assoc->key must be valid because assoc can't change or be
-	       * removed from our chain while we hold at least one lock. If
-	       * the assoc was on our key chain then the key has not been
-	       * deleted yet.
-	       *
-	       * Try to acquire both locks without deadlocking.
+	       * First we need to serialise with pthread_key_delete by locking
+	       * both assoc guards, but in the reverse order to our convention,
+	       * so we must be careful to avoid deadlock.
 	       */
-	      if (pthread_mutex_trylock(&(assoc->key->keyLock)) == EBUSY)
+	      (void) pthread_mutex_lock(&(sp->threadLock));
+
+	      if ((assoc = (ThreadKeyAssoc *)sp->nextAssoc) == NULL)
 		{
+		  /* Finished */
 		  pthread_mutex_unlock(&(sp->threadLock));
-		  Sleep(1); // Ugly.
+		  break;
+		}
+	      else
+		{
 		  /*
-		   * Go around again.
-		   * If pthread_key_delete has removed this assoc in the meantime,
-		   * sp->keys will point to a new assoc.
+		   * assoc->key must be valid because assoc can't change or be
+		   * removed from our chain while we hold at least one lock. If
+		   * the assoc was on our key chain then the key has not been
+		   * deleted yet.
+		   *
+		   * Now try to acquire the second lock without deadlocking.
+		   * If we fail, we need to relinquish the first lock and the
+		   * processor and then try to acquire them all again.
 		   */
-		  continue;
+		  if (pthread_mutex_trylock(&(assoc->key->keyLock)) == EBUSY)
+		    {
+		      pthread_mutex_unlock(&(sp->threadLock));
+		      Sleep(1); // Ugly but necessary to avoid priority effects.
+		      /*
+		       * Go around again.
+		       * If pthread_key_delete has removed this assoc in the meantime,
+		       * sp->nextAssoc will point to a new assoc.
+		       */
+		      continue;
+		    }
 		}
-	    }
-
-	  /* We now hold both locks */
 
-	   sp->nextAssoc = assoc->nextKey;
+	      /* We now hold both locks */
 
-	  /*
-	   * Key still active; pthread_key_delete
-	   * will block on these same mutexes before
-	   * it can release actual key; therefore,
-	   * key is valid and we can call the destroy
-	   * routine;
-	   */
-	  k = assoc->key;
-	  destructor = k->destructor;
-	  value = TlsGetValue(k->key);
-	  TlsSetValue (k->key, NULL);
+	      sp->nextAssoc = assoc->nextKey;
 
-	  // Every assoc->key exists and has a destructor
-	  if (value != NULL && iterations <= PTHREAD_DESTRUCTOR_ITERATIONS)
-	    {
 	      /*
-	       * Unlock both locks before the destructor runs.
-	       * POSIX says pthread_key_delete can be run from destructors,
-	       * and that probably includes with this key as target.
+	       * Key still active; pthread_key_delete
+	       * will block on these same mutexes before
+	       * it can release actual key; therefore,
+	       * key is valid and we can call the destroy
+	       * routine;
 	       */
-	      (void) pthread_mutex_unlock(&(sp->threadLock));
-	      (void) pthread_mutex_unlock(&(k->keyLock));
+	      k = assoc->key;
+	      destructor = k->destructor;
+	      value = TlsGetValue(k->key);
+	      TlsSetValue (k->key, NULL);
+
+	      // Every assoc->key exists and has a destructor
+	      if (value != NULL && iterations <= PTHREAD_DESTRUCTOR_ITERATIONS)
+		{
+		  /*
+		   * Unlock both locks before the destructor runs.
+		   * POSIX says pthread_key_delete can be run from destructors,
+		   * and that probably includes with this key as target.
+		   * pthread_setspecific can also be run from destructors and
+		   * also needs to be able to access the assocs.
+		   */
+		  (void) pthread_mutex_unlock(&(sp->threadLock));
+		  (void) pthread_mutex_unlock(&(k->keyLock));
 
-	      assocsRemaining++;
+		  assocsRemaining++;
 
 #ifdef __cplusplus
 
-	      try
-		{
+		  try
+		    {
+		      /*
+		       * Run the caller's cleanup routine.
+		       */
+		      destructor (value);
+		    }
+		  catch (...)
+		    {
+		      /*
+		       * A system unexpected exception has occurred
+		       * running the user's destructor.
+		       * We get control back within this block in case
+		       * the application has set up it's own terminate
+		       * handler. Since we are leaving the thread we
+		       * should not get any internal pthreads
+		       * exceptions.
+		       */
+		      terminate ();
+		    }
+
+#else /* __cplusplus */
+
 		  /*
 		   * Run the caller's cleanup routine.
 		   */
 		  destructor (value);
+
+#endif /* __cplusplus */
+
 		}
-	      catch (...)
+	      else
 		{
 		  /*
-		   * A system unexpected exception has occurred
-		   * running the user's destructor.
-		   * We get control back within this block in case
-		   * the application has set up it's own terminate
-		   * handler. Since we are leaving the thread we
-		   * should not get any internal pthreads
-		   * exceptions.
+		   * Remove association from both the key and thread chains
+		   * and reclaim it's memory resources.
 		   */
-		  terminate ();
+		  ptw32_tkAssocDestroy (assoc);
+		  (void) pthread_mutex_unlock(&(sp->threadLock));
+		  (void) pthread_mutex_unlock(&(k->keyLock));
 		}
-
-#else /* __cplusplus */
-
-	      /*
-	       * Run the caller's cleanup routine.
-	       */
-	      destructor (value);
-
-#endif /* __cplusplus */
-
 	    }
-	  else
-	    {
-	      /*
-	       * Remove association from both the key and thread chains
-	       * and reclaim it's memory resources.
-	       */
-	      ptw32_tkAssocDestroy (assoc);
-	      (void) pthread_mutex_unlock(&(sp->threadLock));
-	      (void) pthread_mutex_unlock(&(k->keyLock));
-	    }
-	}
 	}
       while (assocsRemaining);
     }