tulip: Fix for MTU problems with 802.1q tagged frames

The original patch was submitted last year but wasn't discussed or applied
because of missing maintainer's CCs. I only fixed some formatting errors,
but as I saw tulip is very badly formatted and needs further work.

Original description:
This patch fixes MTU problem, which occurs when using 802.1q VLANs. We
should allow receiving frames of up to 1518 bytes in length, instead of
1514.

Based on patch written by Ben McKeegan for 2.4.x kernels. It is archived
at http://www.candelatech.com/~greear/vlan/howto.html#tulip
I've adjusted a few things to make it apply on 2.6.x kernels.

Tested on D-Link DFE-570TX quad-fastethernet card.

Signed-off-by: Tomasz Lemiech <szpajder@staszic.waw.pl>
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Signed-off-by: Ben McKeegan <ben@netservers.co.uk>
Acked-by: Grant Grundler <grundler@parisc-linux.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 55 insertions, 29 deletions

diff --git a/drivers/net/tulip/interrupt.c b/drivers/net/tulip/interrupt.c
index 9f946d421088..c8d220cf2cce 100644
--- a/drivers/net/tulip/interrupt.c
+++ b/drivers/net/tulip/interrupt.c
@@ -140,6 +140,7 @@ int tulip_poll(struct napi_struct *napi, int budget)
                /* If we own the next entry, it is a new packet. Send it up. */
                while ( ! (tp->rx_ring[entry].status & cpu_to_le32(DescOwned))) {
                        s32 status = le32_to_cpu(tp->rx_ring[entry].status);
+		       short pkt_len;
 
                        if (tp->dirty_rx + RX_RING_SIZE == tp->cur_rx)
                                break;
@@ -151,8 +152,28 @@ int tulip_poll(struct napi_struct *napi, int budget)
 		       if (++work_done >= budget)
                                goto not_done;
 
-                       if ((status & 0x38008300) != 0x0300) {
-                               if ((status & 0x38000300) != 0x0300) {
+		       /*
+			* Omit the four octet CRC from the length.
+			* (May not be considered valid until we have
+			* checked status for RxLengthOver2047 bits)
+			*/
+		       pkt_len = ((status >> 16) & 0x7ff) - 4;
+
+		       /*
+			* Maximum pkt_len is 1518 (1514 + vlan header)
+			* Anything higher than this is always invalid
+			* regardless of RxLengthOver2047 bits
+			*/
+
+		       if ((status & (RxLengthOver2047 |
+				      RxDescCRCError |
+				      RxDescCollisionSeen |
+				      RxDescRunt |
+				      RxDescDescErr |
+				      RxWholePkt)) != RxWholePkt
+			   || pkt_len > 1518) {
+			       if ((status & (RxLengthOver2047 |
+					      RxWholePkt)) != RxWholePkt) {
                                 /* Ingore earlier buffers. */
                                        if ((status & 0xffff) != 0x7fff) {
                                                if (tulip_debug > 1)
@@ -161,30 +182,23 @@ int tulip_poll(struct napi_struct *napi, int budget)
                                                               dev->name, status);
                                                tp->stats.rx_length_errors++;
                                        }
-                               } else if (status & RxDescFatalErr) {
+			       } else {
                                 /* There was a fatal error. */
                                        if (tulip_debug > 2)
                                                printk(KERN_DEBUG "%s: Receive error, Rx status %8.8x.\n",
                                                       dev->name, status);
                                        tp->stats.rx_errors++; /* end of a packet.*/
-                                       if (status & 0x0890) tp->stats.rx_length_errors++;
+				       if (pkt_len > 1518 ||
+					   (status & RxDescRunt))
+					       tp->stats.rx_length_errors++;
+
                                        if (status & 0x0004) tp->stats.rx_frame_errors++;
                                        if (status & 0x0002) tp->stats.rx_crc_errors++;
                                        if (status & 0x0001) tp->stats.rx_fifo_errors++;
                                }
                        } else {
-                               /* Omit the four octet CRC from the length. */
-                               short pkt_len = ((status >> 16) & 0x7ff) - 4;
                                struct sk_buff *skb;
 
-#ifndef final_version
-                               if (pkt_len > 1518) {
-                                       printk(KERN_WARNING "%s: Bogus packet size of %d (%#x).\n",
-                                              dev->name, pkt_len, pkt_len);
-                                       pkt_len = 1518;
-                                       tp->stats.rx_length_errors++;
-                               }
-#endif
                                /* Check if the packet is long enough to accept without copying
                                   to a minimally-sized skbuff. */
                                if (pkt_len < tulip_rx_copybreak
@@ -356,14 +370,35 @@ static int tulip_rx(struct net_device *dev)
 	/* If we own the next entry, it is a new packet. Send it up. */
 	while ( ! (tp->rx_ring[entry].status & cpu_to_le32(DescOwned))) {
 		s32 status = le32_to_cpu(tp->rx_ring[entry].status);
+		short pkt_len;
 
 		if (tulip_debug > 5)
 			printk(KERN_DEBUG "%s: In tulip_rx(), entry %d %8.8x.\n",
 				   dev->name, entry, status);
 		if (--rx_work_limit < 0)
 			break;
-		if ((status & 0x38008300) != 0x0300) {
-			if ((status & 0x38000300) != 0x0300) {
+
+		/*
+		  Omit the four octet CRC from the length.
+		  (May not be considered valid until we have
+		  checked status for RxLengthOver2047 bits)
+		*/
+		pkt_len = ((status >> 16) & 0x7ff) - 4;
+		/*
+		  Maximum pkt_len is 1518 (1514 + vlan header)
+		  Anything higher than this is always invalid
+		  regardless of RxLengthOver2047 bits
+		*/
+
+		if ((status & (RxLengthOver2047 |
+			       RxDescCRCError |
+			       RxDescCollisionSeen |
+			       RxDescRunt |
+			       RxDescDescErr |
+			       RxWholePkt))        != RxWholePkt
+		     || pkt_len > 1518) {
+			if ((status & (RxLengthOver2047 |
+			     RxWholePkt))         != RxWholePkt) {
 				/* Ingore earlier buffers. */
 				if ((status & 0xffff) != 0x7fff) {
 					if (tulip_debug > 1)
@@ -372,31 +407,22 @@ static int tulip_rx(struct net_device *dev)
 							   dev->name, status);
 					tp->stats.rx_length_errors++;
 				}
-			} else if (status & RxDescFatalErr) {
+			} else {
 				/* There was a fatal error. */
 				if (tulip_debug > 2)
 					printk(KERN_DEBUG "%s: Receive error, Rx status %8.8x.\n",
 						   dev->name, status);
 				tp->stats.rx_errors++; /* end of a packet.*/
-				if (status & 0x0890) tp->stats.rx_length_errors++;
+				if (pkt_len > 1518 ||
+				    (status & RxDescRunt))
+					tp->stats.rx_length_errors++;
 				if (status & 0x0004) tp->stats.rx_frame_errors++;
 				if (status & 0x0002) tp->stats.rx_crc_errors++;
 				if (status & 0x0001) tp->stats.rx_fifo_errors++;
 			}
 		} else {
-			/* Omit the four octet CRC from the length. */
-			short pkt_len = ((status >> 16) & 0x7ff) - 4;
 			struct sk_buff *skb;
 
-#ifndef final_version
-			if (pkt_len > 1518) {
-				printk(KERN_WARNING "%s: Bogus packet size of %d (%#x).\n",
-					   dev->name, pkt_len, pkt_len);
-				pkt_len = 1518;
-				tp->stats.rx_length_errors++;
-			}
-#endif
-
 			/* Check if the packet is long enough to accept without copying
 			   to a minimally-sized skbuff. */
 			if (pkt_len < tulip_rx_copybreak