Staging: gdm724x: gdm_usb: added error checking in do_tx()

Added error checking for alloc_tx_struct in do_tx()

Signed-off-by: Abel Moyo <abelmoyo.ab@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/staging/gdm724x/gdm_usb.c b/drivers/staging/gdm724x/gdm_usb.c
index 483185b..5d44490 100644
--- a/drivers/staging/gdm724x/gdm_usb.c
+++ b/drivers/staging/gdm724x/gdm_usb.c
@@ -682,6 +682,10 @@
 		}
 
 		t = alloc_tx_struct(TX_BUF_SIZE);
+		if (t == NULL) {
+			spin_unlock_irqrestore(&tx->lock, flags);
+			return;
+		}
 		t->callback = NULL;
 		t->tx = tx;
 		t->is_sdu = 1;