[PATCH] [157/275] xhci: Fix an error in count_sg_trbs_needed()

[Andi Kleen]

2.6.35-longterm review patch.  If anyone has any objections, please let me know.

------------------
From: Paul Zimmerman <Paul.Zimmerman@xxxxxxxxxxxx>

commit bcd2fde05341cef0052e49566ec88b406a521cf3 upstream.

The expression

	while (running_total < sg_dma_len(sg))

does not take into account that the remaining data length can be less
than sg_dma_len(sg). In that case, running_total can end up being
greater than the total data length, so an extra TRB is counted.
Changing the expression to

	while (running_total < sg_dma_len(sg) && running_total < temp)

fixes that.

This patch should be queued for stable kernels back to 2.6.31.

Signed-off-by: Paul Zimmerman <paulz@xxxxxxxxxxxx>
Signed-off-by: Sarah Sharp <sarah.a.sharp@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>

---
 drivers/usb/host/xhci-ring.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: linux-2.6.35.y/drivers/usb/host/xhci-ring.c
===================================================================
--- linux-2.6.35.y.orig/drivers/usb/host/xhci-ring.c	2011-03-29 23:03:01.504261681 -0700
+++ linux-2.6.35.y/drivers/usb/host/xhci-ring.c	2011-03-29 23:54:12.392685328 -0700
@@ -1896,7 +1896,7 @@
 			num_trbs++;
 
 		/* How many more 64KB chunks to transfer, how many more TRBs? */
-		while (running_total < sg_dma_len(sg)) {
+		while (running_total < sg_dma_len(sg) && running_total < temp) {
 			num_trbs++;
 			running_total += TRB_MAX_BUFF_SIZE;
 		}
--
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