X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Frts%2FCapability.c;h=d8bdbe6b50fb2965b023fa9bb884eff7112de158;hb=e0b2097136f30331bae67cb01e66bba749d272c1;hp=2dec782fd90f269b34c31af41f6c73a08fddedf3;hpb=6d7576ef2853317e690a7c4e823d7f0bb8d9aaf0;p=ghc-hetmet.git

diff --git a/ghc/rts/Capability.c b/ghc/rts/Capability.c
index 2dec782..d8bdbe6 100644
--- a/ghc/rts/Capability.c
+++ b/ghc/rts/Capability.c
@@ -68,8 +68,8 @@ Condition thread_ready_cond = INIT_COND_VAR;
  * the number of tasks currently blocked waiting on thread_ready_cond.
  * (if > 0 => no need for a new task, just unblock an existing one).
  *
- * waitForWork() takes care of keeping it up-to-date; Task.startTask()
- * uses its current value.
+ * waitForWorkCapability() takes care of keeping it up-to-date;
+ * Task.startTask() uses its current value.
  */
 nat rts_n_waiting_tasks = 0;
 #endif
@@ -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;
 }