[PATCH, RFC] usbmon: correct computing of the ISO packets with mmap

["Németh Márton" <nm127@freemail.hu>]

From: Márton Németh <nm127@freemail.hu>

The length of the isochronous packets were not computed correctly in case of memory
mapped operation because the gaps between the isodesc data were not taken into
account. The last data byte can be found at offset+actual_length of the
last ISO description.

This patch fixes the problem described at https://bugzilla.kernel.org/show_bug.cgi?id=22182 .

Signed-off-by: Márton Németh <nm127@freemail.hu>
---
--- linux-2.6.37-rc1/drivers/usb/mon/mon_bin.c.orig	2010-10-20 22:30:22.000000000 +0200
+++ linux-2.6.37-rc1/drivers/usb/mon/mon_bin.c	2010-11-13 22:29:09.000000000 +0100
@@ -515,6 +515,26 @@ static void mon_bin_event(struct mon_rea
 	}

 	if (rp->mmap_active) {
+		if (usb_endpoint_xfer_isoc(epd) &&
+		    ((usb_urb_dir_in(urb) && ev_type == 'C') ||
+		     (usb_urb_dir_out(urb) && ev_type == 'S'))) {
+			int i;
+
+			/* Search for the last ISO descritor with OK status
+			 * and non-zero length
+			 */
+			length = 0;
+			i = urb->number_of_packets - 1;
+			while (0 <= i &&
+			       (urb->iso_frame_desc[i].status != 0 ||
+			        urb->iso_frame_desc[i].actual_length == 0)) {
+				i--;
+			}
+			if (0 <= i) {
+				length = urb->iso_frame_desc[i].offset +
+					 urb->iso_frame_desc[i].actual_length;
+			}
+		}
 		offset = mon_buff_area_alloc_contiguous(rp,
 						 length + PKT_SIZE + lendesc);
 	} else {