mport->inb_msg[mbox].mcback = minb;
 
                rc = mport->ops->open_inb_mbox(mport, dev_id, mbox, entries);
+               if (rc) {
+                       mport->inb_msg[mbox].mcback = NULL;
+                       mport->inb_msg[mbox].res = NULL;
+                       release_resource(res);
+                       kfree(res);
+               }
        } else
                rc = -ENOMEM;
 
  */
 int rio_release_inb_mbox(struct rio_mport *mport, int mbox)
 {
-       if (mport->ops->close_inb_mbox) {
-               mport->ops->close_inb_mbox(mport, mbox);
+       int rc;
 
-               /* Release the mailbox resource */
-               return release_resource(mport->inb_msg[mbox].res);
-       } else
-               return -ENOSYS;
+       if (!mport->ops->close_inb_mbox || !mport->inb_msg[mbox].res)
+               return -EINVAL;
+
+       mport->ops->close_inb_mbox(mport, mbox);
+       mport->inb_msg[mbox].mcback = NULL;
+
+       rc = release_resource(mport->inb_msg[mbox].res);
+       if (rc)
+               return rc;
+
+       kfree(mport->inb_msg[mbox].res);
+       mport->inb_msg[mbox].res = NULL;
+
+       return 0;
 }
 
 /**
                mport->outb_msg[mbox].mcback = moutb;
 
                rc = mport->ops->open_outb_mbox(mport, dev_id, mbox, entries);
+               if (rc) {
+                       mport->outb_msg[mbox].mcback = NULL;
+                       mport->outb_msg[mbox].res = NULL;
+                       release_resource(res);
+                       kfree(res);
+               }
        } else
                rc = -ENOMEM;
 
  */
 int rio_release_outb_mbox(struct rio_mport *mport, int mbox)
 {
-       if (mport->ops->close_outb_mbox) {
-               mport->ops->close_outb_mbox(mport, mbox);
+       int rc;
 
-               /* Release the mailbox resource */
-               return release_resource(mport->outb_msg[mbox].res);
-       } else
-               return -ENOSYS;
+       if (!mport->ops->close_outb_mbox || !mport->outb_msg[mbox].res)
+               return -EINVAL;
+
+       mport->ops->close_outb_mbox(mport, mbox);
+       mport->outb_msg[mbox].mcback = NULL;
+
+       rc = release_resource(mport->outb_msg[mbox].res);
+       if (rc)
+               return rc;
+
+       kfree(mport->outb_msg[mbox].res);
+       mport->outb_msg[mbox].res = NULL;
+
+       return 0;
 }
 
 /**