[project @ 2002-12-05 23:49:43 by mthomas]

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

diff --git a/ghc/rts/Capability.c b/ghc/rts/Capability.c
index 638dd4a..d8bdbe6 100644 (file)
--- a/ghc/rts/Capability.c
+++ b/ghc/rts/Capability.c
@@ -214,13 +214,13 @@ void releaseCapability(Capability* cap
  * Function: grabReturnCapability(Capability**)
  *
  * Purpose:  when an OS thread returns from an external call,
- * it calls grabReturningCapability() (via Schedule.resumeThread())
+ * it calls grabReturnCapability() (via Schedule.resumeThread())
  * to wait for permissions to enter the RTS & communicate the
- * result of the ext. call back to the Haskell thread that
+ * result of the external call back to the Haskell thread that
  * made it.
  *
- * Pre-condition:  pMutex isn't held.
- * Post-condition: pMutex is held and a capability has
+ * Pre-condition:  pMutex is held.
+ * Post-condition: pMutex is still held and a capability has
  *                 been assigned to the worker thread.
  */
 void
@@ -228,7 +228,6 @@ grabReturnCapability(Mutex* pMutex, Capability** pCap)
 {
   IF_DEBUG(scheduler,
           fprintf(stderr,"worker (%ld): returning, waiting for lock.\n", osThreadId()));
-  ACQUIRE_LOCK(pMutex);
   rts_n_waiting_workers++;
   IF_DEBUG(scheduler,
           fprintf(stderr,"worker (%ld): returning; workers waiting: %d\n",
@@ -260,22 +259,14 @@ grabReturnCapability(Mutex* pMutex, Capability** pCap)
  *                 been given back.
  */
 void
-yieldToReturningWorker(Mutex* pMutex, Capability* cap)
+yieldToReturningWorker(Mutex* pMutex, Capability** pCap)
 {
   if ( rts_n_waiting_workers > 0 && noCapabilities() ) {
     IF_DEBUG(scheduler,
             fprintf(stderr,"worker thread (%ld): giving up RTS token\n", osThreadId()));
-    releaseCapability(cap);
-    RELEASE_LOCK(pMutex);
-    yieldThread();
-    /* At this point, pMutex has been given up & we've 
-     * forced a thread context switch. Guaranteed to be
-     * enough for the signalled worker thread to race
-     * ahead of us?
-     */
-
-    /* Re-grab the mutex */
-    ACQUIRE_LOCK(pMutex);
+    releaseCapability(*pCap);
+    /* And wait for work */
+    waitForWorkCapability(pMutex, pCap, rtsFalse);
   }
   return;
 }