NTB: variable dereferenced before check

commit 186f27ff upstream.

Correct instances of variable dereferencing before checking its value on
the functions exported to the client drivers.  Also, add sanity checks
for all exported functions.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jon Mason <jon.mason@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/ntb/ntb_transport.c

@@ -1210,12 +1210,14 @@ EXPORT_SYMBOL_GPL(ntb_transport_create_queue);
  */
 void ntb_transport_free_queue(struct ntb_transport_qp *qp)
 {
-	struct pci_dev *pdev = ntb_query_pdev(qp->ndev);
+	struct pci_dev *pdev;
 	struct ntb_queue_entry *entry;
 
 	if (!qp)
 		return;
 
+	pdev = ntb_query_pdev(qp->ndev);
+
 	cancel_delayed_work_sync(&qp->link_work);
 
 	ntb_unregister_db_callback(qp->ndev, qp->qp_num);
@@ -1371,12 +1373,13 @@ EXPORT_SYMBOL_GPL(ntb_transport_link_up);
  */
 void ntb_transport_link_down(struct ntb_transport_qp *qp)
 {
-	struct pci_dev *pdev = ntb_query_pdev(qp->ndev);
+	struct pci_dev *pdev;
 	int rc, val;
 
 	if (!qp)
 		return;
 
+	pdev = ntb_query_pdev(qp->ndev);
 	qp->client_ready = NTB_LINK_DOWN;
 
 	rc = ntb_read_local_spad(qp->ndev, QP_LINKS, &val);
@@ -1408,6 +1411,9 @@ EXPORT_SYMBOL_GPL(ntb_transport_link_down);
  */
 bool ntb_transport_link_query(struct ntb_transport_qp *qp)
 {
+	if (!qp)
+		return false;
+
 	return qp->qp_link == NTB_LINK_UP;
 }
 EXPORT_SYMBOL_GPL(ntb_transport_link_query);
@@ -1422,6 +1428,9 @@ EXPORT_SYMBOL_GPL(ntb_transport_link_query);
  */
 unsigned char ntb_transport_qp_num(struct ntb_transport_qp *qp)
 {
+	if (!qp)
+		return 0;
+
 	return qp->qp_num;
 }
 EXPORT_SYMBOL_GPL(ntb_transport_qp_num);
@@ -1436,6 +1445,9 @@ EXPORT_SYMBOL_GPL(ntb_transport_qp_num);
  */
 unsigned int ntb_transport_max_size(struct ntb_transport_qp *qp)
 {
+	if (!qp)
+		return 0;
+
 	return qp->tx_max_frame - sizeof(struct ntb_payload_header);
 }
 EXPORT_SYMBOL_GPL(ntb_transport_max_size);