RDMA/cxgb3: Clean up properly on FW mismatch failures

FW mismatches can cause a crash in the iw_cxgb3 event handler.

- NULL the t3cdev->ulp pointer on failures in cxio_rdev_open()
- Silently ignore events when the ulp ptr is NULL in iwch_err_handler()
Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/hw/cxgb3/cxio_hal.c

@@ -1034,6 +1034,7 @@ err3:
 err2:
 	cxio_hal_destroy_ctrl_qp(rdev_p);
 err1:
+	rdev_p->t3cdev_p->ulp = NULL;
 	list_del(&rdev_p->entry);
 	return err;
 }

drivers/infiniband/hw/cxgb3/iwch.c

@@ -165,10 +165,13 @@ static void close_rnic_dev(struct t3cdev *tdev)
 static void iwch_event_handler(struct t3cdev *tdev, u32 evt, u32 port_id)
 {
 	struct cxio_rdev *rdev = tdev->ulp;
-	struct iwch_dev *rnicp = rdev_to_iwch_dev(rdev);
+	struct iwch_dev *rnicp;
 	struct ib_event event;
 	u32    portnum = port_id + 1;
 
+	if (!rdev)
+		return;
+	rnicp = rdev_to_iwch_dev(rdev);
 	switch (evt) {
 	case OFFLOAD_STATUS_DOWN: {
 		rdev->flags = CXIO_ERROR_FATAL;