USB: fix usbmon and DMA mapping for scatter-gather URBs

This patch (as1368) fixes a rather obscure bug in usbmon: When tracing
URBs sent by the scatter-gather library, it accesses the data buffers
while they are still mapped for DMA.

The solution is to move the mapping and unmapping out of the s-g
library and into the usual place in hcd.c.  This requires the addition
of new URB flag bits to describe the kind of mapping needed, since we
have to call dma_map_sg() if the HCD supports native scatter-gather
operation and dma_map_page() if it doesn't.  The nice thing about
having the new flags is that they simplify the testing for unmapping.

The patch removes the only caller of usb_buffer_[un]map_sg(), so those
functions are #if'ed out.  A later patch will remove them entirely.

As a result of this change, urb->sg will be set in situations where
it wasn't set previously.  Hence the xhci and whci drivers are
adjusted to test urb->num_sgs instead, which retains its original
meaning and is nonzero only when the HCD has to handle a scatterlist.

Finally, even when a submission error occurs we don't want to hand
URBs to usbmon before they are unmapped.  The submission path is
rearranged so that map_urb_for_dma() is called only for non-root-hub
URBs and unmap_urb_for_dma() is called immediately after a submission
error.  This simplifies the error handling.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 9 insertions, 0 deletions

diff --git a/include/linux/usb.h b/include/linux/usb.h
index 739f1fd1cc15..99833029e5a8 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -965,10 +965,19 @@ extern int usb_disabled(void);
                                          * needed */
 #define URB_FREE_BUFFER         0x0100  /* Free transfer buffer with the URB */
 
+/* The following flags are used internally by usbcore and HCDs */
 #define URB_DIR_IN              0x0200  /* Transfer from device to host */
 #define URB_DIR_OUT             0
 #define URB_DIR_MASK            URB_DIR_IN
 
+#define URB_DMA_MAP_SINGLE      0x00010000      /* Non-scatter-gather mapping */
+#define URB_DMA_MAP_PAGE        0x00020000      /* HCD-unsupported S-G */
+#define URB_DMA_MAP_SG          0x00040000      /* HCD-supported S-G */
+#define URB_MAP_LOCAL           0x00080000      /* HCD-local-memory mapping */
+#define URB_SETUP_MAP_SINGLE    0x00100000      /* Setup packet DMA mapped */
+#define URB_SETUP_MAP_LOCAL     0x00200000      /* HCD-local setup packet */
+#define URB_DMA_SG_COMBINED     0x00400000      /* S-G entries were combined */
+
 struct usb_iso_packet_descriptor {
         unsigned int offset;
         unsigned int length;            /* expected length */