[68/68] xhci: Fix an error in count_sg_trbs_needed()

From: Greg KH
Date: Mon Feb 28 2011 - 11:38:34 EST

2.6.32-longterm review patch. If anyone has any objections, please let us 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>

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

--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -1496,7 +1496,7 @@ static unsigned int count_sg_trbs_needed

/* 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) {
running_total += TRB_MAX_BUFF_SIZE;

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