USB: cdc-wdm: no need to use usb_alloc_coherent

As Documentation/usb/dma.txt states:

  Most drivers should *NOT* be using these primitives; they don't need
  to use this type of memory (dma-coherent), and memory returned from
  kmalloc() will work just fine.

This driver handle only very low bandwith transfers.  It is not an
obvious candidate for usb_alloc_coherent().

Using these calls only serves to complicate the code for no gain,
as has been shown by multiple bugs related to this allocation path.

Signed-off-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 9 insertions, 30 deletions

diff --git a/drivers/usb/class/cdc-wdm.c b/drivers/usb/class/cdc-wdm.c
index 846dfa603447..8909058b1bb1 100644
--- a/drivers/usb/class/cdc-wdm.c
+++ b/drivers/usb/class/cdc-wdm.c
@@ -256,14 +256,8 @@ static void free_urbs(struct wdm_device *desc)
 
 static void cleanup(struct wdm_device *desc)
 {
-        usb_free_coherent(interface_to_usbdev(desc->intf),
-                          desc->wMaxPacketSize,
-                          desc->sbuf,
-                          desc->validity->transfer_dma);
-        usb_free_coherent(interface_to_usbdev(desc->intf),
-                          desc->bMaxPacketSize0,
-                          desc->inbuf,
-                          desc->response->transfer_dma);
+        kfree(desc->sbuf);
+        kfree(desc->inbuf);
         kfree(desc->orq);
         kfree(desc->irq);
         kfree(desc->ubuf);
@@ -688,19 +682,13 @@ next_desc:
         if (!desc->ubuf)
                 goto err;
 
-        desc->sbuf = usb_alloc_coherent(interface_to_usbdev(intf),
-                                        desc->wMaxPacketSize,
-                                        GFP_KERNEL,
-                                        &desc->validity->transfer_dma);
+        desc->sbuf = kmalloc(desc->wMaxPacketSize, GFP_KERNEL);
         if (!desc->sbuf)
                 goto err;
 
-        desc->inbuf = usb_alloc_coherent(interface_to_usbdev(intf),
-                                         desc->wMaxCommand,
-                                         GFP_KERNEL,
-                                         &desc->response->transfer_dma);
+        desc->inbuf = kmalloc(desc->wMaxCommand, GFP_KERNEL);
         if (!desc->inbuf)
-                goto err2;
+                goto err;
 
         usb_fill_int_urb(
                 desc->validity,
@@ -712,7 +700,6 @@ next_desc:
                 desc,
                 ep->bInterval
         );
-        desc->validity->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
 
         desc->irq->bRequestType = (USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE);
         desc->irq->bRequest = USB_CDC_GET_ENCAPSULATED_RESPONSE;
@@ -731,30 +718,22 @@ next_desc:
                 wdm_in_callback,
                 desc
         );
-        desc->response->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
 
         usb_set_intfdata(intf, desc);
         rv = usb_register_dev(intf, &wdm_class);
         if (rv < 0)
-                goto err3;
+                goto err2;
         else
                 dev_info(&intf->dev, "cdc-wdm%d: USB WDM device\n",
                         intf->minor - WDM_MINOR_BASE);
 out:
         return rv;
-err3:
-        usb_set_intfdata(intf, NULL);
-        usb_free_coherent(interface_to_usbdev(desc->intf),
-                          desc->bMaxPacketSize0,
-                        desc->inbuf,
-                        desc->response->transfer_dma);
 err2:
-        usb_free_coherent(interface_to_usbdev(desc->intf),
-                          desc->wMaxPacketSize,
-                          desc->sbuf,
-                          desc->validity->transfer_dma);
+        usb_set_intfdata(intf, NULL);
 err:
         free_urbs(desc);
+        kfree(desc->inbuf);
+        kfree(desc->sbuf);
         kfree(desc->ubuf);
         kfree(desc->orq);
         kfree(desc->irq);