[PATCH] net: asix: handle packets crossing URB boundaries

[Rolf Evers-Fischer <embedded24@evers-fischer.de>]

From: Lucas Stach <dev@lynxeye.de>

ASIX AX88772B started to pack data even more tightly. Packets and the ASIX packet
header may now cross URB boundaries. To handle this we have to introduce
some state between individual calls to asix_rx_fixup().

Signed-off-by: Lucas Stach <dev@lynxeye.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
[ Rolf: ported from kernel to barebox 2014.09.0 ]
Signed-off-by: Rolf Evers-Fischer <embedded24@evers-fischer.de>
---
 drivers/net/usb/asix.c | 123 ++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 91 insertions(+), 32 deletions(-)

diff --git a/drivers/net/usb/asix.c b/drivers/net/usb/asix.c
index d6ac322..14a8c76 100644
--- a/drivers/net/usb/asix.c
+++ b/drivers/net/usb/asix.c
@@ -7,6 +7,7 @@
 #include <errno.h>
 #include <malloc.h>
 #include <asm/byteorder.h>
+#include <asm/unaligned.h>
 
 /* ASIX AX8817X based USB 2.0 Ethernet Devices */
 
@@ -134,6 +135,8 @@
 
 #define FLAG_EEPROM_MAC		(1UL << 0) /* init device MAC from eeprom */
 
+#define RX_FIXUP_SIZE	1514
+
 /* This structure cannot exceed sizeof(unsigned long [5]) AKA 20 bytes */
 struct asix_data {
 	u8 multi_filter[AX_MCAST_FILTER_SIZE];
@@ -150,6 +153,18 @@ struct ax88172_int_data {
 	__le16 res3;
 } __attribute__ ((packed));
 
+struct asix_rx_fixup_info {
+	u32 header;
+	u16 size;
+	u16 offset;
+	bool split_head;
+	unsigned char ax_skb[RX_FIXUP_SIZE];
+};
+
+struct asix_common_private {
+	struct asix_rx_fixup_info rx_fixup_info;
+};
+
 static int asix_read_cmd(struct usbnet *dev, u8 cmd, u16 value, u16 index,
 			    u16 size, void *data)
 {
@@ -409,49 +424,87 @@ static int ax88172_get_ethaddr(struct eth_device *edev, unsigned char *adr)
 	return 0;
 }
 
-static int asix_rx_fixup(struct usbnet *dev, void *buf, int len)
+int asix_rx_fixup_internal(struct usbnet *dev, void *buf, int len,
+			   struct asix_rx_fixup_info *rx)
 {
-	unsigned int header;
-	unsigned short size;
-
-	memcpy(&header, (void*) buf, sizeof(header));
-	le32_to_cpus(&header);
-	buf += 4;
-	len -= 4;
-
-	while (len > 0) {
-		if ((header & 0x07ff) != ((~header >> 16) & 0x07ff))
-			dev_err(&dev->edev.dev, "asix_rx_fixup() Bad Header Length\n");
-
-		/* get the packet length */
-		size = (unsigned short) (header & 0x07ff);
-
-		if (size > 1514) {
-			dev_err(&dev->edev.dev, "asix_rx_fixup() Bad RX Length %d\n", size);
-			return 0;
+	int offset = 0;
+
+	while (offset + sizeof(u16) < len) {
+		u16 remaining = 0;
+
+		if (!rx->size) {
+			if ((len - offset == sizeof(u16)) ||
+			    rx->split_head) {
+				if (!rx->split_head) {
+					rx->header = get_unaligned_le16(
+							buf + offset);
+					rx->split_head = true;
+					offset += sizeof(u16);
+					break;
+				} else {
+					rx->header |= (get_unaligned_le16(
+							buf + offset)
+							<< 16);
+					rx->split_head = false;
+					offset += sizeof(u16);
+				}
+			} else {
+				rx->header = get_unaligned_le32(buf +
+								offset);
+				offset += sizeof(u32);
+			}
+			rx->offset = 0U;
+
+			/* get the packet length */
+			rx->size = (u16) (rx->header & 0x7ff);
+			if (rx->size != ((~rx->header >> 16) & 0x7ff)) {
+				dev_err(&dev->edev.dev, "asix_rx_fixup() Bad Header Length 0x%x, offset %d\n",
+					   rx->header, offset);
+				rx->size = 0;
+				return -1;
+			}
 		}
+		if (rx->size > RX_FIXUP_SIZE) {
+			dev_err(&dev->edev.dev, "asix_rx_fixup() Bad RX Length %d\n",
+				   rx->size);
+			rx->offset = 0U;
+			rx->size = 0U;
 
-		net_receive(&dev->edev, buf, size);
+			return -1;
+		}
 
-		buf += ((size + 1) & 0xfffe);
-		len -= ((size + 1) & 0xfffe);
+		if (rx->size > (len - offset)) {
+			remaining = rx->size - (len - offset);
+			rx->size = len - offset;
+		}
 
-		if (len == 0)
-			break;
+		memcpy(rx->ax_skb + rx->offset, buf + offset, rx->size);
+		rx->offset += rx->size;
+		if (!remaining)
+			net_receive(&dev->edev, rx->ax_skb,
+						(u16) (rx->header & 0x7ff));
 
-		memcpy(&header, (void*) buf, sizeof(header));
-		le32_to_cpus(&header);
-		buf += 4;
-		len -= 4;
+		offset += ((rx->size + 1) & 0xfffe);
+		rx->size = remaining;
 	}
 
-	if (len < 0) {
-		dev_err(&dev->edev.dev,"asix_rx_fixup() Bad SKB Length %d\n", len);
+	if (len != offset) {
+		dev_err(&dev->edev.dev, "asix_rx_fixup() Bad SKB Length %d, %d\n",
+			   len, offset);
 		return -1;
 	}
+
 	return 0;
 }
 
+static int asix_rx_fixup_common(struct usbnet *dev, void *buf, int len)
+{
+	struct asix_common_private *dp = dev->driver_priv;
+	struct asix_rx_fixup_info *rx = &dp->rx_fixup_info;
+
+	return asix_rx_fixup_internal(dev, buf, len, rx);
+}
+
 static int asix_tx_fixup(struct usbnet *dev,
 				void *buf, int len,
 				void *nbuf, int *nlen)
@@ -632,6 +685,11 @@ static int ax88772_bind(struct usbnet *dev)
 		dev->rx_urb_size = 2048;
 	}
 
+	dev->driver_priv = kzalloc(sizeof(struct asix_common_private),
+				GFP_KERNEL);
+	if (!dev->driver_priv)
+		return -ENOMEM;
+
 	return 0;
 
 out:
@@ -641,6 +699,7 @@ out:
 static void asix_unbind(struct usbnet *dev)
 {
 	mdiobus_unregister(&dev->miibus);
+	kfree(dev->driver_priv);
 }
 
 static struct driver_info ax8817x_info = {
@@ -688,7 +747,7 @@ static struct driver_info ax88772_info = {
 	.bind = ax88772_bind,
 	.unbind = asix_unbind,
 	.flags = FLAG_ETHER | FLAG_FRAMING_AX,
-	.rx_fixup = asix_rx_fixup,
+	.rx_fixup = asix_rx_fixup_common,
 	.tx_fixup = asix_tx_fixup,
 };
 
@@ -697,7 +756,7 @@ static struct driver_info ax88772b_info = {
 	.bind = ax88772_bind,
 	.unbind = asix_unbind,
 	.flags = FLAG_ETHER | FLAG_FRAMING_AX,
-	.rx_fixup = asix_rx_fixup,
+	.rx_fixup = asix_rx_fixup_common,
 	.tx_fixup = asix_tx_fixup,
 	.data = FLAG_EEPROM_MAC,
 };
-- 
1.9.1


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