Improve handling of USB device re-open in the LibUSB v1.x API.

Make sure the "device_is_gone" flag is cleared after every successful open,
so that the "device_is_gone" flag doesn't persist forever.

Found by:	sergii.dmytruk@3mdeb.com
PR:		256296
MFC after:	1 week
Sponsored by:	Mellanox Technologies // NVIDIA Networking

lib/libusb/libusb10.c

@@ -529,6 +529,15 @@ libusb_open(libusb_device *dev, libusb_device_handle **devh)
 		libusb_unref_device(dev);
 		return (LIBUSB_ERROR_NO_MEM);
 	}
+
+	/*
+	 * Clear the device gone flag, in case the device was opened
+	 * after a re-attach, to allow new transaction:
+	 */
+	CTX_LOCK(ctx);
+	dev->device_is_gone = 0;
+	CTX_UNLOCK(ctx);
+
 	libusb10_add_pollfd(ctx, &dev->dev_poll, pdev, libusb20_dev_get_fd(pdev), POLLIN |
 	    POLLOUT | POLLRDNORM | POLLWRNORM);
 

lib/libusb/libusb10_io.c

@@ -165,8 +165,16 @@ libusb10_handle_events_sub(struct libusb_context *ctx, struct timeval *tv)
 				err = libusb20_dev_process(ppdev[i]);
 
 				if (err) {
-					/* set device is gone */
-					dev->device_is_gone = 1;
+					/*
+					 * When the device is opened
+					 * set the "device_is_gone"
+					 * flag. This prevents the
+					 * client from submitting new
+					 * USB transfers to a detached
+					 * device.
+					 */
+					if (ppdev[i]->is_opened)
+						dev->device_is_gone = 1;
 
 					/* remove USB device from polling loop */
 					libusb10_remove_pollfd(dev->ctx, &dev->dev_poll);

lib/libusb/libusb20.c

@@ -608,6 +608,11 @@ libusb20_dev_close(struct libusb20_device *pdev)
 
 	pdev->is_opened = 0;
 
+	/*
+	 * Make sure libusb20_tr_get_pointer() fails:
+	 */
+	pdev->nTransfer = 0;
+
 	/* 
 	 * The following variable is only used by the libusb v0.1
 	 * compat layer: