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xhci: Fix an error in count_sg_trbs_needed()
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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@synopsys.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: stable@kernel.org
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Paul Zimmerman authored and Sarah Sharp committed Feb 20, 2011
1 parent 5807795 commit bcd2fde
Showing 1 changed file with 1 addition and 1 deletion.
2 changes: 1 addition & 1 deletion drivers/usb/host/xhci-ring.c
Original file line number Diff line number Diff line change
Expand Up @@ -2374,7 +2374,7 @@ static unsigned int count_sg_trbs_needed(struct xhci_hcd *xhci, struct urb *urb)
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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