From 288edd19d71d9d092650a569a2ea93f18c81faef Mon Sep 17 00:00:00 2001
From: Hans Petter Selasky <hselasky@FreeBSD.org>
Date: Tue, 29 Mar 2016 10:47:14 +0000
Subject: [PATCH] Verify that all segments in the loaded segment list are back
 to back with regard to the page offset, and not only the two first ones.

---
 sys/dev/usb/usb_busdma.c | 27 ++++++++++++++++-----------
 1 file changed, 16 insertions(+), 11 deletions(-)

diff --git a/sys/dev/usb/usb_busdma.c b/sys/dev/usb/usb_busdma.c
index 821e0fb816eb..75378a2d568b 100644
--- a/sys/dev/usb/usb_busdma.c
+++ b/sys/dev/usb/usb_busdma.c
@@ -472,17 +472,22 @@ usb_pc_common_mem_cb(void *arg, bus_dma_segment_t *segs,
 	pc->page_offset_buf = rem;
 	pc->page_offset_end += rem;
 #ifdef USB_DEBUG
-	if (nseg > 1 &&
-	    ((segs->ds_addr + segs->ds_len) & (USB_PAGE_SIZE - 1)) !=
-	    ((segs + 1)->ds_addr & (USB_PAGE_SIZE - 1))) {
-		/*
-		 * This check verifies there is no page offset hole
-		 * between the first and second segment. See the
-		 * BUS_DMA_KEEP_PG_OFFSET flag.
-		 */
-		DPRINTFN(0, "Page offset was not preserved\n");
-		error = 1;
-		goto done;
+	if (nseg > 1) {
+		int x;
+
+		for (x = 0; x != nseg - 1; x++) {
+			if (((segs[x].ds_addr + segs[x].ds_len) & (USB_PAGE_SIZE - 1)) ==
+			    ((segs[x + 1].ds_addr & (USB_PAGE_SIZE - 1))))
+				continue;
+			/*
+			 * This check verifies there is no page offset
+			 * hole between any of the segments. See the
+			 * BUS_DMA_KEEP_PG_OFFSET flag.
+			 */
+			DPRINTFN(0, "Page offset was not preserved\n");
+			error = 1;
+			goto done;
+		}
 	}
 #endif
 	while (pc->ismultiseg) {