sky2: fix VLAN receive processing (resend)

The length check for truncated frames was not correctly handling
the case where VLAN acceleration had already read the tag.
Also, the Yukon EX has some features that use high bit of status
as security tag.
Signed-off-by: Pierre-Yves Ritschard <pyr@spootnik.org>
Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/net/sky2.c

@@ -2103,6 +2103,13 @@ static struct sk_buff *sky2_receive(struct net_device *dev,
  	struct sky2_port *sky2 = netdev_priv(dev);
 	struct rx_ring_info *re = sky2->rx_ring + sky2->rx_next;
 	struct sk_buff *skb = NULL;
+	u16 count = (status & GMR_FS_LEN) >> 16;
+
+#ifdef SKY2_VLAN_TAG_USED
+	/* Account for vlan tag */
+	if (sky2->vlgrp && (status & GMR_FS_VLAN))
+		count -= VLAN_HLEN;
+#endif
 
 	if (unlikely(netif_msg_rx_status(sky2)))
 		printk(KERN_DEBUG PFX "%s: rx slot %u status 0x%x len %d\n",
@@ -2117,7 +2124,8 @@ static struct sk_buff *sky2_receive(struct net_device *dev,
 	if (!(status & GMR_FS_RX_OK))
 		goto resubmit;
 
-	if (status >> 16 != length)
+	/* if length reported by DMA does not match PHY, packet was truncated */
+	if (length != count)
 		goto len_mismatch;
 
 	if (length < copybreak)
@@ -2133,6 +2141,10 @@ static struct sk_buff *sky2_receive(struct net_device *dev,
 	/* Truncation of overlength packets
 	   causes PHY length to not match MAC length */
 	++sky2->net_stats.rx_length_errors;
+	if (netif_msg_rx_err(sky2) && net_ratelimit())
+		pr_info(PFX "%s: rx length mismatch: length %d status %#x\n",
+			dev->name, length, status);
+	goto resubmit;
 
 error:
 	++sky2->net_stats.rx_errors;

drivers/net/sky2.h

@@ -1668,7 +1668,7 @@ enum {
 
 /* Receive Frame Status Encoding */
 enum {
-	GMR_FS_LEN	= 0xffff<<16, /* Bit 31..16:	Rx Frame Length */
+	GMR_FS_LEN	= 0x7fff<<16, /* Bit 30..16:	Rx Frame Length */
 	GMR_FS_VLAN	= 1<<13, /* VLAN Packet */
 	GMR_FS_JABBER	= 1<<12, /* Jabber Packet */
 	GMR_FS_UN_SIZE	= 1<<11, /* Undersize Packet */