Add freeScheduler/freeTaskManager and call it later than exitScheduler

We were freeing the tasks in exitScheduler (stopTaskManager) before
exitStorage (stat_exit), but the latter needs to walk down the list
printing stats. Resulted in segfaults with commands like
    ghc -v0 -e main q.hs -H32m -H32m +RTS -Sstderr
(where q.hs is trivial), but very sensitive to exact commandline and
libc version or something.

5 files changed, 28 insertions, 3 deletions

diff --git a/rts/RtsStartup.c b/rts/RtsStartup.c
index 5bb980674d..937334bdab 100644
--- a/rts/RtsStartup.c
+++ b/rts/RtsStartup.c
@@ -438,6 +438,9 @@ hs_exit(void)
     // also outputs the stats (+RTS -s) info.
     exitStorage();
     
+    /* free the tasks */
+    freeScheduler();
+
     /* free shared Typeable store */
     exitTypeableStore();
 
diff --git a/rts/Schedule.c b/rts/Schedule.c
index cf62c5ae7a..77dcf411c7 100644
--- a/rts/Schedule.c
+++ b/rts/Schedule.c
@@ -2582,6 +2582,12 @@ exitScheduler( void )
 #endif
 }
 
+void
+freeScheduler( void )
+{
+    freeTaskManager();
+}
+
 /* ---------------------------------------------------------------------------
    Where are the roots that we know about?
 
diff --git a/rts/Schedule.h b/rts/Schedule.h
index 2afedeec86..ba5efc29ad 100644
--- a/rts/Schedule.h
+++ b/rts/Schedule.h
@@ -19,6 +19,7 @@
  */
 void initScheduler (void);
 void exitScheduler (void);
+void freeScheduler (void);
 
 // Place a new thread on the run queue of the current Capability
 void scheduleThread (Capability *cap, StgTSO *tso);
diff --git a/rts/Task.c b/rts/Task.c
index 588d414d87..0e51dbf124 100644
--- a/rts/Task.c
+++ b/rts/Task.c
@@ -68,19 +68,33 @@ initTaskManager (void)
 void
 stopTaskManager (void)
 {
-    Task *task, *next;
+    Task *task;
 
     debugTrace(DEBUG_sched, 
 	       "stopping task manager, %d tasks still running",
 	       tasksRunning);
 
     ACQUIRE_LOCK(&sched_mutex);
-    for (task = task_free_list; task != NULL; task = next) {
-        next = task->next;
+    for (task = task_free_list; task != NULL; task = task->next) {
 #if defined(THREADED_RTS)
         closeCondition(&task->cond);
         closeMutex(&task->lock);
 #endif
+    }
+    RELEASE_LOCK(&sched_mutex);
+}
+
+
+void
+freeTaskManager (void)
+{
+    Task *task, *next;
+
+    debugTrace(DEBUG_sched, "freeing task manager");
+
+    ACQUIRE_LOCK(&sched_mutex);
+    for (task = task_free_list; task != NULL; task = next) {
+        next = task->next;
         stgFree(task);
     }
     task_free_list = NULL;
diff --git a/rts/Task.h b/rts/Task.h
index cc450a74a1..3b7a08ee96 100644
--- a/rts/Task.h
+++ b/rts/Task.h
@@ -170,6 +170,7 @@ extern Task *all_tasks;
 //
 void initTaskManager (void);
 void stopTaskManager (void);
+void freeTaskManager (void);
 
 // Create a new Task for a bound thread
 // Requires: sched_mutex.