Detab TcUnify

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

diff --git a/rts/Capability.c b/rts/Capability.c
index 564a20f..ffaa372 100644 (file)
--- a/rts/Capability.c
+++ b/rts/Capability.c
@@ -639,7 +639,7 @@ prodOneCapability (void)
  * ------------------------------------------------------------------------- */
 
 void
-shutdownCapability (Capability *cap, Task *task)
+shutdownCapability (Capability *cap, Task *task, rtsBool safe)
 {
     nat i;
 
@@ -677,7 +677,7 @@ shutdownCapability (Capability *cap, Task *task)
             for (t = cap->spare_workers; t != NULL; t = t->next) {
                 if (!osThreadIsAlive(t->id)) {
                     debugTrace(DEBUG_sched, 
-                               "worker thread %p has died unexpectedly", t->id);
+                               "worker thread %p has died unexpectedly", (void *)t->id);
                         if (!prev) {
                             cap->spare_workers = t->next;
                         } else {
@@ -696,8 +696,24 @@ shutdownCapability (Capability *cap, Task *task)
            yieldThread();
            continue;
        }
+
+        // If "safe", then busy-wait for any threads currently doing
+        // foreign calls.  If we're about to unload this DLL, for
+        // example, we need to be sure that there are no OS threads
+        // that will try to return to code that has been unloaded.
+        // We can be a bit more relaxed when this is a standalone
+        // program that is about to terminate, and let safe=false.
+        if (cap->suspended_ccalling_tasks && safe) {
+           debugTrace(DEBUG_sched, 
+                      "thread(s) are involved in foreign calls, yielding");
+            cap->running_task = NULL;
+           RELEASE_LOCK(&cap->lock);
+            yieldThread();
+            continue;
+        }
+            
        debugTrace(DEBUG_sched, "capability %d is stopped.", cap->no);
-    freeCapability(cap);
+        freeCapability(cap);
        RELEASE_LOCK(&cap->lock);
        break;
     }