The check printing out the "WARN Wrong bounce buffer write length:"
uses incorrect values when comparing bytes written from scatterlist
to bounce buffer. Actual copied lengths are fine.

The used seg->bounce_len will be set to equal new_buf_len a few lines later
in the code, but is incorrect when doing the comparison.

The patch which added this false warning was backported to 4.8+ kernels
so this should be backported as far as well.

Cc: <> # v4.8+
Fixes: 597c56e372da ("xhci: update bounce buffer with correct sg num")
Signed-off-by: Mathias Nyman <>
 drivers/usb/host/xhci-ring.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 9741cdeea9d7..85ceb43e3405 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -3202,10 +3202,10 @@ static int xhci_align_td(struct xhci_hcd *xhci, struct 
urb *urb, u32 enqd_len,
        if (usb_urb_dir_out(urb)) {
                len = sg_pcopy_to_buffer(urb->sg, urb->num_sgs,
                                   seg->bounce_buf, new_buff_len, enqd_len);
-               if (len != seg->bounce_len)
+               if (len != new_buff_len)
                                "WARN Wrong bounce buffer write length: %zu != 
-                               len, seg->bounce_len);
+                               len, new_buff_len);
                seg->bounce_dma = dma_map_single(dev, seg->bounce_buf,
                                                 max_pkt, DMA_TO_DEVICE);
        } else {

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