binfmt/nxflat.c: Update to last NxFLAT change: The logic must respect…

… the reference count before freeing the dspace memory region.

binfmt/nxflat.c

@@ -246,17 +246,27 @@ static int nxflat_unloadbinary(FAR struct binary_s *binp)
 
   if (dspace != NULL)
     {
-      /* Free dspace region */
+      /* Check if this is the last reference to dspace.  It may still be
+       * needed by other threads.  In that case, it must persist after this
+       * thread terminates.
+       */
 
-      kumm_free(dspace->region);
-      dspace->region = 0;
-    }
+      if (dspace->crefs == 1)
+         {
+          /* Free the dspace region */
+
+          kumm_free(dspace->region);
+          dspace->region = NULL;
 
-  /* Mark alloc[0] (dspace) as freed */
+          /* Mark alloc[0] (dspace) as freed */
 
- binp->alloc[0] = NULL;
+           binp->alloc[0] = NULL;
 
- /* dspace container will be freed in sched/sched_releasetcb */
+          /* The reference count will be decremented to zero and the dspace
+           * container will be freed in sched/sched_releasetcb.c
+           */
+        }
+    }
 
  return OK;
 }

sched/sched/sched_releasetcb.c

@@ -168,7 +168,7 @@ int sched_releasetcb(FAR struct tcb_s *tcb, uint8_t ttype)
 #ifdef CONFIG_PIC
       /* Delete the task's allocated DSpace region (external modules only) */
 
-      if (tcb->dspace)
+      if (tcb->dspace != NULL)
         {
           if (tcb->dspace->crefs <= 1)
             {