linux-kernel - [PATCH v2 2/3] USB: ehci-tegra: fix inefficient copy of unaligned buffers

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Date:	Thu, 23 Apr 2015 16:06:51 +0200
From:	Johan Hovold <johan@...nel.org>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Felipe Balbi <balbi@...com>,
	Alan Stern <stern@...land.harvard.edu>
Cc:	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
	Stephen Warren <swarren@...dotorg.org>,
	Thierry Reding <thierry.reding@...il.com>,
	Alexandre Courbot <gnurou@...il.com>,
	linux-tegra@...r.kernel.org, Johan Hovold <johan@...nel.org>
Subject: [PATCH v2 2/3] USB: ehci-tegra: fix inefficient copy of unaligned buffers

Make sure only to copy any actual data rather than the whole buffer,
when releasing the temporary buffer used for unaligned non-isochronous
transfers.

Compile-tested only.

Signed-off-by: Johan Hovold <johan@...nel.org>
---
 drivers/usb/host/ehci-tegra.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/host/ehci-tegra.c b/drivers/usb/host/ehci-tegra.c
index ff9af29b4e9f..4031b372008e 100644
--- a/drivers/usb/host/ehci-tegra.c
+++ b/drivers/usb/host/ehci-tegra.c
@@ -304,6 +304,7 @@ struct dma_aligned_buffer {
 static void free_dma_aligned_buffer(struct urb *urb)
 {
 	struct dma_aligned_buffer *temp;
+	size_t length;
 
 	if (!(urb->transfer_flags & URB_ALIGNED_TEMP_BUFFER))
 		return;
@@ -311,9 +312,14 @@ static void free_dma_aligned_buffer(struct urb *urb)
 	temp = container_of(urb->transfer_buffer,
 		struct dma_aligned_buffer, data);
 
-	if (usb_urb_dir_in(urb))
-		memcpy(temp->old_xfer_buffer, temp->data,
-		       urb->transfer_buffer_length);
+	if (usb_urb_dir_in(urb)) {
+		if (usb_pipeisoc(urb->pipe))
+			length = urb->transfer_buffer_length;
+		else
+			length = urb->actual_length;
+
+		memcpy(temp->old_xfer_buffer, temp->data, length);
+	}
 	urb->transfer_buffer = temp->old_xfer_buffer;
 	kfree(temp->kmalloc_ptr);
 
-- 
2.0.5

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