diff mbox

[PATCHv3,9/9] net: fec: fix regression on i.MX28 introduced by rx_copybreak support

Message ID 1414502584-10583-10-git-send-email-LW@KARO-electronics.de
State Changes Requested, archived
Delegated to: David Miller
Headers show

Commit Message

Lothar Waßmann Oct. 28, 2014, 1:23 p.m. UTC
commit 1b7bde6d659d ("net: fec: implement rx_copybreak to improve rx performance")
introduced a regression for i.MX28. The swap_buffer() function doing
the endian conversion of the received data on i.MX28 may access memory
beyond the actual packet size in the DMA buffer. fec_enet_copybreak()
does not copy those bytes, so that the last bytes of a packet may be
filled with invalid data after swapping.
This will likely lead to checksum errors on received packets.
E.g. when trying to mount an NFS rootfs:
UDP: bad checksum. From 192.168.1.225:111 to 192.168.100.73:44662 ulen 36

Do the byte swapping and copying to the new skb in one go if
necessary.

Signed-off-by: Lothar Waßmann <LW@KARO-electronics.de>
---
 drivers/net/ethernet/freescale/fec_main.c |   22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

Comments

Stefan Wahren Nov. 3, 2014, 10:58 p.m. UTC | #1
Hi Lothar,

> Lothar Waßmann <LW@KARO-electronics.de> hat am 28. Oktober 2014 um 14:23
> geschrieben:
>
>
> commit 1b7bde6d659d ("net: fec: implement rx_copybreak to improve rx
> performance")
> introduced a regression for i.MX28. The swap_buffer() function doing
> the endian conversion of the received data on i.MX28 may access memory
> beyond the actual packet size in the DMA buffer. fec_enet_copybreak()
> does not copy those bytes, so that the last bytes of a packet may be
> filled with invalid data after swapping.
> This will likely lead to checksum errors on received packets.
> E.g. when trying to mount an NFS rootfs:
> UDP: bad checksum. From 192.168.1.225:111 to 192.168.100.73:44662 ulen 36

i think i experience the same problem with 3.18-rc2 on my mx28 board. I get
strange warnings about unexpected bytes from ping on my mx28 board and ping to
my mx28 board fails because of no response.

After applying the complete patch series these problems disappear. I'm looking
forward to see V4.

Thanks Stefan
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diff mbox

Patch

diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index e52864c..5ee4912 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -294,7 +294,16 @@  static void swap_buffer(void *bufaddr, int len)
 
 	for (i = 0; i < len; i += 4, buf++)
 		swab32s(buf);
+}
+
+static void swap_buffer2(void *dst_buf, void *src_buf, int len)
+{
+	int i;
+	unsigned int *src = src_buf;
+	unsigned int *dst = dst_buf;
 
+	for (i = 0; i < len; i += 4, src++, dst++)
+		*dst = swab32p(src);
 }
 
 static void fec_dump(struct net_device *ndev)
@@ -1292,7 +1301,7 @@  fec_enet_new_rxbdp(struct net_device *ndev, struct bufdesc *bdp, struct sk_buff
 }
 
 static bool fec_enet_copybreak(struct net_device *ndev, struct sk_buff **skb,
-			       struct bufdesc *bdp, u32 length)
+			       struct bufdesc *bdp, u32 length, bool swap)
 {
 	struct  fec_enet_private *fep = netdev_priv(ndev);
 	struct sk_buff *new_skb;
@@ -1307,7 +1316,10 @@  static bool fec_enet_copybreak(struct net_device *ndev, struct sk_buff **skb,
 	dma_sync_single_for_cpu(&fep->pdev->dev, bdp->cbd_bufaddr,
 				FEC_ENET_RX_FRSIZE - fep->rx_align,
 				DMA_FROM_DEVICE);
-	memcpy(new_skb->data, (*skb)->data, length);
+	if (!swap)
+		memcpy(new_skb->data, (*skb)->data, length);
+	else
+		swap_buffer2(new_skb->data, (*skb)->data, length);
 	*skb = new_skb;
 
 	return true;
@@ -1335,6 +1347,7 @@  fec_enet_rx_queue(struct net_device *ndev, int budget, u16 queue_id)
 	u16	vlan_tag;
 	int	index = 0;
 	bool	is_copybreak;
+	bool	need_swap = fep->quirks & FEC_QUIRK_SWAP_FRAME;
 
 #ifdef CONFIG_M532x
 	flush_cache_all();
@@ -1398,7 +1411,8 @@  fec_enet_rx_queue(struct net_device *ndev, int budget, u16 queue_id)
 		 * include that when passing upstream as it messes up
 		 * bridging applications.
 		 */
-		is_copybreak = fec_enet_copybreak(ndev, &skb, bdp, pkt_len - 4);
+		is_copybreak = fec_enet_copybreak(ndev, &skb, bdp, pkt_len - 4,
+						  need_swap);
 		if (!is_copybreak) {
 			skb_new = netdev_alloc_skb(ndev, FEC_ENET_RX_FRSIZE);
 			if (unlikely(!skb_new)) {
@@ -1413,7 +1427,7 @@  fec_enet_rx_queue(struct net_device *ndev, int budget, u16 queue_id)
 		prefetch(skb->data - NET_IP_ALIGN);
 		skb_put(skb, pkt_len - 4);
 		data = skb->data;
-		if (fep->quirks & FEC_QUIRK_SWAP_FRAME)
+		if (!is_copybreak && need_swap)
 			swap_buffer(data, pkt_len);
 
 		/* Extract the enhanced buffer descriptor */