USB: add scatter-gather support to usbmon

[safe/jmp/linux-2.6] / drivers / usb / mon / mon_text.c

diff --git a/drivers/usb/mon/mon_text.c b/drivers/usb/mon/mon_text.c
index 9f1a922..047568f 100644 (file)
--- a/drivers/usb/mon/mon_text.c
+++ b/drivers/usb/mon/mon_text.c
@@ -10,6 +10,7 @@
 #include <linux/time.h>
 #include <linux/mutex.h>
 #include <linux/debugfs.h>
+#include <linux/scatterlist.h>
 #include <asm/uaccess.h>
 
 #include "usb_mon.h"
@@ -137,6 +138,8 @@ static inline char mon_text_get_setup(struct mon_event_text *ep,
 static inline char mon_text_get_data(struct mon_event_text *ep, struct urb *urb,
     int len, char ev_type, struct mon_bus *mbus)
 {
+       void *src;
+
        if (len <= 0)
                return 'L';
        if (len >= DATA_MAX)
@@ -150,10 +153,24 @@ static inline char mon_text_get_data(struct mon_event_text *ep, struct urb *urb,
                        return '>';
        }
 
-       if (urb->transfer_buffer == NULL)
-               return 'Z';     /* '0' would be not as pretty. */
+       if (urb->num_sgs == 0) {
+               src = urb->transfer_buffer;
+               if (src == NULL)
+                       return 'Z';     /* '0' would be not as pretty. */
+       } else {
+               struct scatterlist *sg = urb->sg->sg;
+
+               /* If IOMMU coalescing occurred, we cannot trust sg_page */
+               if (urb->sg->nents != urb->num_sgs ||
+                               PageHighMem(sg_page(sg)))
+                       return 'D';
+
+               /* For the text interface we copy only the first sg buffer */
+               len = min_t(int, sg->length, len);
+               src = sg_virt(sg);
+       }
 
-       memcpy(ep->data, urb->transfer_buffer, len);
+       memcpy(ep->data, src, len);
        return 0;
 }