1 files changed, 90 insertions, 4 deletions

diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
index 0b4685aad2d5..fca7735fc660 100644
--- a/drivers/usb/core/usb.c
+++ b/drivers/usb/core/usb.c
@@ -695,15 +695,16 @@ struct usb_device *usb_alloc_dev(struct usb_device *parent,
 		device_set_of_node_from_dev(&dev->dev, bus->sysdev);
 		dev_set_name(&dev->dev, "usb%d", bus->busnum);
 	} else {
+		int n;
+
 		/* match any labeling on the hubs; it's one-based */
 		if (parent->devpath[0] == '0') {
-			snprintf(dev->devpath, sizeof dev->devpath,
-				"%d", port1);
+			n = snprintf(dev->devpath, sizeof(dev->devpath), "%d", port1);
 			/* Root ports are not counted in route string */
 			dev->route = 0;
 		} else {
-			snprintf(dev->devpath, sizeof dev->devpath,
-				"%s.%d", parent->devpath, port1);
+			n = snprintf(dev->devpath, sizeof(dev->devpath), "%s.%d",
+				     parent->devpath, port1);
 			/* Route string assumes hubs have less than 16 ports */
 			if (port1 < 15)
 				dev->route = parent->route +
@@ -712,6 +713,11 @@ struct usb_device *usb_alloc_dev(struct usb_device *parent,
 				dev->route = parent->route +
 					(15 << ((parent->level - 1)*4));
 		}
+		if (n >= sizeof(dev->devpath)) {
+			usb_put_hcd(bus_to_hcd(bus));
+			usb_put_dev(dev);
+			return NULL;
+		}
 
 		dev->dev.parent = &parent->dev;
 		dev_set_name(&dev->dev, "%d-%s", bus->busnum, dev->devpath);
@@ -1024,6 +1030,86 @@ void usb_free_coherent(struct usb_device *dev, size_t size, void *addr,
 }
 EXPORT_SYMBOL_GPL(usb_free_coherent);
 
+/**
+ * usb_alloc_noncoherent - allocate dma-noncoherent buffer for URB_NO_xxx_DMA_MAP
+ * @dev: device the buffer will be used with
+ * @size: requested buffer size
+ * @mem_flags: affect whether allocation may block
+ * @dma: used to return DMA address of buffer
+ * @dir: DMA transfer direction
+ * @table: used to return sg_table of allocated memory
+ *
+ * To explicit manage the memory ownership for the kernel vs the device by
+ * USB core, the user needs save sg_table to urb->sgt. Then USB core will
+ * do DMA sync for CPU and device properly.
+ *
+ * When the buffer is no longer used, free it with usb_free_noncoherent().
+ *
+ * Return: Either null (indicating no buffer could be allocated), or the
+ * cpu-space pointer to a buffer that may be used to perform DMA to the
+ * specified device.  Such cpu-space buffers are returned along with the DMA
+ * address (through the pointer provided).
+ */
+void *usb_alloc_noncoherent(struct usb_device *dev, size_t size,
+			    gfp_t mem_flags, dma_addr_t *dma,
+			    enum dma_data_direction dir,
+			    struct sg_table **table)
+{
+	struct device *dmadev;
+	struct sg_table *sgt;
+	void *buffer;
+
+	if (!dev || !dev->bus)
+		return NULL;
+
+	dmadev = bus_to_hcd(dev->bus)->self.sysdev;
+
+	sgt = dma_alloc_noncontiguous(dmadev, size, dir, mem_flags, 0);
+	if (!sgt)
+		return NULL;
+
+	buffer = dma_vmap_noncontiguous(dmadev, size, sgt);
+	if (!buffer) {
+		dma_free_noncontiguous(dmadev, size, sgt, dir);
+		return NULL;
+	}
+
+	*table = sgt;
+	*dma = sg_dma_address(sgt->sgl);
+
+	return buffer;
+}
+EXPORT_SYMBOL_GPL(usb_alloc_noncoherent);
+
+/**
+ * usb_free_noncoherent - free memory allocated with usb_alloc_noncoherent()
+ * @dev: device the buffer was used with
+ * @size: requested buffer size
+ * @addr: CPU address of buffer
+ * @dir: DMA transfer direction
+ * @table: describe the allocated and DMA mapped memory,
+ *
+ * This reclaims an I/O buffer, letting it be reused.  The memory must have
+ * been allocated using usb_alloc_noncoherent(), and the parameters must match
+ * those provided in that allocation request.
+ */
+void usb_free_noncoherent(struct usb_device *dev, size_t size,
+			  void *addr, enum dma_data_direction dir,
+			  struct sg_table *table)
+{
+	struct device *dmadev;
+
+	if (!dev || !dev->bus)
+		return;
+	if (!addr)
+		return;
+
+	dmadev = bus_to_hcd(dev->bus)->self.sysdev;
+	dma_vunmap_noncontiguous(dmadev, addr);
+	dma_free_noncontiguous(dmadev, size, table, dir);
+}
+EXPORT_SYMBOL_GPL(usb_free_noncoherent);
+
 /*
  * Notifications of device and interface registration
  */