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>

3 files changed, 9 insertions, 6 deletions

diff --git a/drivers/usb/mon/mon_main.c b/drivers/usb/mon/mon_main.c
index e0ed36cdfd8b..394bbf2f68d4 100644
--- a/drivers/usb/mon/mon_main.c
+++ b/drivers/usb/mon/mon_main.c
@@ -301,6 +301,7 @@ static void mon_bus_init(struct dentry *mondir, struct usb_bus *ubus)
          */
         mbus->u_bus = ubus;
         ubus->mon_bus = mbus;
+        mbus->uses_dma = ubus->uses_dma;
 
         rc = snprintf(name, NAMESZ, "%dt", ubus->busnum);
         if (rc <= 0 || rc >= NAMESZ)
diff --git a/drivers/usb/mon/mon_text.c b/drivers/usb/mon/mon_text.c
index 775e374a960c..7a2346c53284 100644
--- a/drivers/usb/mon/mon_text.c
+++ b/drivers/usb/mon/mon_text.c
@@ -75,13 +75,13 @@ static void mon_text_ctor(void *, kmem_cache_t *, unsigned long);
  */
 
 static inline char mon_text_get_setup(struct mon_event_text *ep,
-    struct urb *urb, char ev_type)
+    struct urb *urb, char ev_type, struct mon_bus *mbus)
 {
 
         if (!usb_pipecontrol(urb->pipe) || ev_type != 'S')
                 return '-';
 
-        if (urb->transfer_flags & URB_NO_SETUP_DMA_MAP)
+        if (mbus->uses_dma && (urb->transfer_flags & URB_NO_SETUP_DMA_MAP))
                 return mon_dmapeek(ep->setup, urb->setup_dma, SETUP_MAX);
         if (urb->setup_packet == NULL)
                 return 'Z';     /* '0' would be not as pretty. */
@@ -91,7 +91,7 @@ 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)
+    int len, char ev_type, struct mon_bus *mbus)
 {
         int pipe = urb->pipe;
 
@@ -117,7 +117,7 @@ static inline char mon_text_get_data(struct mon_event_text *ep, struct urb *urb,
          * contain non-NULL garbage in case the upper level promised to
          * set DMA for the HCD.
          */
-        if (urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP)
+        if (mbus->uses_dma && (urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP))
                 return mon_dmapeek(ep->data, urb->transfer_dma, len);
 
         if (urb->transfer_buffer == NULL)
@@ -161,8 +161,9 @@ static void mon_text_event(struct mon_reader_text *rp, struct urb *urb,
         /* Collecting status makes debugging sense for submits, too */
         ep->status = urb->status;
 
-        ep->setup_flag = mon_text_get_setup(ep, urb, ev_type);
-        ep->data_flag = mon_text_get_data(ep, urb, ep->length, ev_type);
+        ep->setup_flag = mon_text_get_setup(ep, urb, ev_type, rp->r.m_bus);
+        ep->data_flag = mon_text_get_data(ep, urb, ep->length, ev_type,
+                        rp->r.m_bus);
 
         rp->nevents++;
         list_add_tail(&ep->e_link, &rp->e_list);
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 */