[PATCH 2/2] USB: ehci-tegra: fix inefficient copy of unaligned buffers

From: Johan Hovold
Date: Tue Apr 07 2015 - 05:48:50 EST

Make sure only to copy any actual data rather than the whole buffer,
when releasing the temporary buffer used for unaligned transfer buffers.

Note that the corresponding fix of musb also fixes a lockup on
disconnect, where repeated failed transfers would starve the hub
workqueue from processing the disconnect, which would have prevented the
urbs from being resubmitted. In this case there is no data to forward,
but the full buffer length was being copied nonetheless.

Compile-tested only.

Fixes: fbf9865c6d96 ("USB: ehci: tegra: Align DMA transfers to 32 bytes")
Cc: stable <stable@xxxxxxxxxxxxxxx> # v2.6.39
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
drivers/usb/host/ehci-tegra.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/host/ehci-tegra.c b/drivers/usb/host/ehci-tegra.c
index ff9af29b4e9f..dfe2a7abc36d 100644
--- a/drivers/usb/host/ehci-tegra.c
+++ b/drivers/usb/host/ehci-tegra.c
@@ -313,7 +313,7 @@ static void free_dma_aligned_buffer(struct urb *urb)

if (usb_urb_dir_in(urb))
memcpy(temp->old_xfer_buffer, temp->data,
- urb->transfer_buffer_length);
+ urb->actual_length);
urb->transfer_buffer = temp->old_xfer_buffer;


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