[PATCH 03/10] usb: catch attempts to submit urbs with a vmalloc'd transfer buffer

[Mathias Nyman <mathias.nyman@linux.intel.com>]

From: Dan Williams <dan.j.williams@intel.com>

Save someone else the debug cycles of figuring out why a driver's
transfer request is failing or causing undefined system behavior.
Buffers submitted for dma must come from GFP allocated / DMA-able
memory.

Return -EAGAIN matching the return value for dma_mapping_error() cases.

Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
---
 drivers/usb/core/hcd.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index 9c4e292..adddc66 100644
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -1502,6 +1502,9 @@ int usb_hcd_map_urb_for_dma(struct usb_hcd *hcd, struct urb *urb,
 					ret = -EAGAIN;
 				else
 					urb->transfer_flags |= URB_DMA_MAP_PAGE;
+			} else if (is_vmalloc_addr(urb->transfer_buffer)) {
+				WARN_ONCE(1, "transfer buffer not dma capable\n");
+				ret = -EAGAIN;
 			} else {
 				urb->transfer_dma = dma_map_single(
 						hcd->self.controller,
-- 
1.8.3.2