USB: add usbfs snooping for REAP and DISCARD

This patch improves the usbfs_snoop debugging facility by adding
messages for a couple of significant events which, up to now, have not
been logged.  The events are reaping and discarding (i.e.,
cancelling) an URB.  The debugging messages include the userspace
address of the URB being reaped or discarded.

The reaping messages have to be added in four places, in order to
handle blocking and non-blocking reaps in both normal and 32-bit
compatibility mode.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/core/devio.c

@@ -1716,8 +1716,12 @@ static struct async *reap_as(struct usb_dev_state *ps)
 static int proc_reapurb(struct usb_dev_state *ps, void __user *arg)
 {
 	struct async *as = reap_as(ps);
+
 	if (as) {
-		int retval = processcompl(as, (void __user * __user *)arg);
+		int retval;
+
+		snoop(&ps->dev->dev, "reap %p\n", as->userurb);
+		retval = processcompl(as, (void __user * __user *)arg);
 		free_async(as);
 		return retval;
 	}
@@ -1733,6 +1737,7 @@ static int proc_reapurbnonblock(struct usb_dev_state *ps, void __user *arg)
 
 	as = async_getcompleted(ps);
 	if (as) {
+		snoop(&ps->dev->dev, "reap %p\n", as->userurb);
 		retval = processcompl(as, (void __user * __user *)arg);
 		free_async(as);
 	} else {
@@ -1859,8 +1864,12 @@ static int processcompl_compat(struct async *as, void __user * __user *arg)
 static int proc_reapurb_compat(struct usb_dev_state *ps, void __user *arg)
 {
 	struct async *as = reap_as(ps);
+
 	if (as) {
-		int retval = processcompl_compat(as, (void __user * __user *)arg);
+		int retval;
+
+		snoop(&ps->dev->dev, "reap %p\n", as->userurb);
+		retval = processcompl_compat(as, (void __user * __user *)arg);
 		free_async(as);
 		return retval;
 	}
@@ -1876,6 +1885,7 @@ static int proc_reapurbnonblock_compat(struct usb_dev_state *ps, void __user *ar
 
 	as = async_getcompleted(ps);
 	if (as) {
+		snoop(&ps->dev->dev, "reap %p\n", as->userurb);
 		retval = processcompl_compat(as, (void __user * __user *)arg);
 		free_async(as);
 	} else {
@@ -2280,7 +2290,7 @@ static long usbdev_do_ioctl(struct file *file, unsigned int cmd,
 #endif
 
 	case USBDEVFS_DISCARDURB:
-		snoop(&dev->dev, "%s: DISCARDURB\n", __func__);
+		snoop(&dev->dev, "%s: DISCARDURB %p\n", __func__, p);
 		ret = proc_unlinkurb(ps, p);
 		break;