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

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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>
This commit is contained in:
Alan Stern
2010-04-02 13:27:28 -04:00
committed by Greg Kroah-Hartman
parent 0ff8d1b3c8
commit ff9c895f07
9 changed files with 139 additions and 109 deletions
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9
include/linux/usb.h
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@ -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 */