[3.16.y-ckt stable] Patch "net: mvneta: fix DMA buffer unmapping in mvneta_rx()" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    net: mvneta: fix DMA buffer unmapping in mvneta_rx()

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt19.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 72ec9d919bc29c4cfa8425427a2a28eeb4a14373 Mon Sep 17 00:00:00 2001
From: Simon Guinot <simon.guinot at sequanux.org>
Date: Tue, 15 Sep 2015 22:41:21 +0200
Subject: net: mvneta: fix DMA buffer unmapping in mvneta_rx()

commit daf158d0d544cec80b7b30deff8cfc59a6e17610 upstream.

This patch fixes a regression introduced by the commit a84e32894191
("net: mvneta: fix refilling for Rx DMA buffers"). Due to this commit
the newly allocated Rx buffers are DMA-unmapped in place of those passed
to the networking stack. Obviously, this causes data corruptions.

This patch fixes the issue by ensuring that the right Rx buffers are
DMA-unmapped.

Reported-by: Oren Laskin <oren at igneous.io>
Signed-off-by: Simon Guinot <simon.guinot at sequanux.org>
Fixes: a84e32894191 ("net: mvneta: fix refilling for Rx DMA buffers")
Tested-by: Oren Laskin <oren at igneous.io>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/net/ethernet/marvell/mvneta.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
index 109908574224..03ab691ad683 100644
--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c
@@ -1450,6 +1450,7 @@ static int mvneta_rx(struct mvneta_port *pp, int rx_todo,
 		struct mvneta_rx_desc *rx_desc = mvneta_rxq_next_desc_get(rxq);
 		struct sk_buff *skb;
 		unsigned char *data;
+		dma_addr_t phys_addr;
 		u32 rx_status;
 		int rx_bytes, err;

@@ -1457,6 +1458,7 @@ static int mvneta_rx(struct mvneta_port *pp, int rx_todo,
 		rx_status = rx_desc->status;
 		rx_bytes = rx_desc->data_size - (ETH_FCS_LEN + MVNETA_MH_SIZE);
 		data = (unsigned char *)rx_desc->buf_cookie;
+		phys_addr = rx_desc->buf_phys_addr;

 		if (!mvneta_rxq_desc_is_first_last(rx_status) ||
 		    (rx_status & MVNETA_RXD_ERR_SUMMARY)) {
@@ -1505,7 +1507,7 @@ static int mvneta_rx(struct mvneta_port *pp, int rx_todo,
 		if (!skb)
 			goto err_drop_frame;

-		dma_unmap_single(dev->dev.parent, rx_desc->buf_phys_addr,
+		dma_unmap_single(dev->dev.parent, phys_addr,
 				 MVNETA_RX_BUF_SIZE(pp->pkt_size), DMA_FROM_DEVICE);

 		rcvd_pkts++;