Close the races between throwTo and thread completion

[ghc-hetmet.git] / rts / RaiseAsync.c

diff --git a/rts/RaiseAsync.c b/rts/RaiseAsync.c
index e65cea3..2f072d5 100644 (file)
--- a/rts/RaiseAsync.c
+++ b/rts/RaiseAsync.c
@@ -264,6 +264,15 @@ check_target:
                target = target->_link;
                goto retry;
            }
+            // check again for ThreadComplete and ThreadKilled.  This
+            // cooperates with scheduleHandleThreadFinished to ensure
+            // that we never miss any threads that are throwing an
+            // exception to a thread in the process of terminating.
+            if (target->what_next == ThreadComplete
+                || target->what_next == ThreadKilled) {
+               unlockTSO(target);
+                return THROWTO_SUCCESS;
+            }
            blockedThrowTo(cap,source,target);
            *out = target;
            return THROWTO_BLOCKED;
@@ -564,12 +573,10 @@ maybePerformBlockedException (Capability *cap, StgTSO *tso)
 void
 awakenBlockedExceptionQueue (Capability *cap, StgTSO *tso)
 {
-    if (tso->blocked_exceptions != END_TSO_QUEUE) {
-       lockTSO(tso);
-       awakenBlockedQueue(cap, tso->blocked_exceptions);
-       tso->blocked_exceptions = END_TSO_QUEUE;
-       unlockTSO(tso);
-    }
+    lockTSO(tso);
+    awakenBlockedQueue(cap, tso->blocked_exceptions);
+    tso->blocked_exceptions = END_TSO_QUEUE;
+    unlockTSO(tso);
 }    
 
 static void