usbmon: don't call mon_dmapeek if DMA isn't being used

This patch (as755b) fixes a bug in usbmon.  Rather than assuming all
USB host controllers use DMA, the code will check the usb_bus data
structure.  If DMA isn't used, we don't want to try peeking into a
non-existent DMA buffer!

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

1 files changed, 1 insertions, 0 deletions

diff --git a/drivers/usb/mon/usb_mon.h b/drivers/usb/mon/usb_mon.h
index 50efc8ee7c21..ab9d02d5df77 100644
--- a/drivers/usb/mon/usb_mon.h
+++ b/drivers/usb/mon/usb_mon.h
@@ -20,6 +20,7 @@ struct mon_bus {
         struct dentry *dent_s;          /* Debugging file */
         struct dentry *dent_t;          /* Text interface file */
         struct usb_bus *u_bus;
+        int uses_dma;
 
         /* Ref */
         int nreaders;                   /* Under mon_lock AND mbus->lock */