diff --git a/drivers/usb/usb-skeleton.c b/drivers/usb/usb-skeleton.c
index 5ffa3e2..768fda9 100644
--- a/drivers/usb/usb-skeleton.c
+++ b/drivers/usb/usb-skeleton.c
@@ -399,9 +399,16 @@
 		goto exit;
 
 	/* limit the number of URBs in flight to stop a user from using up all RAM */
-	if (down_interruptible(&dev->limit_sem)) {
-		retval = -ERESTARTSYS;
-		goto exit;
+	if (!file->f_flags & O_NONBLOCK) {
+		if (down_interruptible(&dev->limit_sem)) {
+			retval = -ERESTARTSYS;
+			goto exit;
+		}
+	} else {
+		if (down_trylock(&dev->limit_sem)) {
+			retval = -EAGAIN;
+			goto exit;
+		}
 	}
 
 	spin_lock_irq(&dev->err_lock);