Allow the number of capabilities to be increased at runtime (#3729)

At present the number of capabilities can only be *increased*, not
decreased.  The latter presents a few more challenges!

1 files changed, 28 insertions, 0 deletions

diff --git a/rts/Task.c b/rts/Task.c
index d72d8a9085..36dd0a94b9 100644
--- a/rts/Task.c
+++ b/rts/Task.c
@@ -325,6 +325,34 @@ discardTasksExcept (Task *keep)
     RELEASE_LOCK(&all_tasks_mutex);
 }
 
+//
+// After the capabilities[] array has moved, we have to adjust all
+// (Capability *) pointers to point to the new array.  The old array
+// is still valid at this point.
+//
+void updateCapabilityRefs (void)
+{
+    Task *task;
+    InCall *incall;
+
+    ACQUIRE_LOCK(&all_tasks_mutex);
+
+    for (task = all_tasks; task != NULL; task=task->all_link) {
+        if (task->cap != NULL) {
+            task->cap = &capabilities[task->cap->no];
+        }
+
+        for (incall = task->incall; incall != NULL; incall = incall->prev_stack) {
+            if (incall->suspended_cap != NULL) {
+                incall->suspended_cap = &capabilities[incall->suspended_cap->no];
+            }
+        }
+    }
+
+    RELEASE_LOCK(&all_tasks_mutex);
+}
+
+
 void
 taskTimeStamp (Task *task USED_IF_THREADS)
 {