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Commit f7ea3337 authored by Paul Janzen's avatar Paul Janzen Committed by Jeff Garzik
Browse files

[PATCH] mv643xx_eth: Fix handling of small, unaligned fragments 



Fix handling of small, unaligned fragments.
It also solves a potential deadlock if skb_linearize() returns -ENOMEM.

Signed-off-by: default avatarPaul Janzen <pcj@linux.sez.to>
Signed-off-by: default avatarDale Farnsworth <dale@farnsworth.org>

 mv643xx_eth.c |   54 +++++++++++++++++++++++++++++++-----------------------
 1 file changed, 31 insertions(+), 23 deletions(-)
Signed-off-by: default avatarJeff Garzik <jgarzik@pobox.com>
parent b44cd572

drivers/net/mv643xx_eth.c

+31 −23
Original line number Diff line number Diff line
@@ -1093,6 +1093,25 @@ static int mv643xx_poll(struct net_device *dev, int *budget) 
}

#endif



/* Hardware can't handle unaligned fragments smaller than 9 bytes.

 * This helper function detects that case.

 */



static inline unsigned int has_tiny_unaligned_frags(struct sk_buff *skb)

{

        unsigned int frag;

        skb_frag_t *fragp;



        for (frag = 0; frag < skb_shinfo(skb)->nr_frags; frag++) {

                fragp = &skb_shinfo(skb)->frags[frag];

                if (fragp->size <= 8 && fragp->page_offset & 0x7)

                        return 1;



        }

        return 0;

}





/*

 * mv643xx_eth_start_xmit

 *
@@ -1136,12 +1155,19 @@ static int mv643xx_eth_start_xmit(struct sk_buff *skb, struct net_device *dev) 
		return 1;

	}



#ifdef MV643XX_CHECKSUM_OFFLOAD_TX

	if (has_tiny_unaligned_frags(skb)) {

		if ((skb_linearize(skb, GFP_ATOMIC) != 0)) {

			stats->tx_dropped++;

			printk(KERN_DEBUG "%s: failed to linearize tiny "

					"unaligned fragment\n", dev->name);

			return 1;

		}

	}



	spin_lock_irqsave(&mp->lock, flags);



	/* Update packet info data structure -- DMA owned, first last */

#ifdef MV643XX_CHECKSUM_OFFLOAD_TX

	if (!skb_shinfo(skb)->nr_frags) {

linear:

		if (skb->ip_summed != CHECKSUM_HW) {

			/* Errata BTS #50, IHL must be 5 if no HW checksum */

			pkt_info.cmd_sts = ETH_TX_ENABLE_INTERRUPT |
@@ -1183,26 +1209,6 @@ static int mv643xx_eth_start_xmit(struct sk_buff *skb, struct net_device *dev) 
	} else {

		unsigned int frag;



		/* Since hardware can't handle unaligned fragments smaller

		 * than 9 bytes, if we find any, we linearize the skb

		 * and start again.  When I've seen it, it's always been

		 * the first frag (probably near the end of the page),

		 * but we check all frags to be safe.

		 */

		for (frag = 0; frag < skb_shinfo(skb)->nr_frags; frag++) {

			skb_frag_t *fragp;



			fragp = &skb_shinfo(skb)->frags[frag];

			if (fragp->size <= 8 && fragp->page_offset & 0x7) {

				skb_linearize(skb, GFP_ATOMIC);

				printk(KERN_DEBUG "%s: unaligned tiny fragment"

						"%d of %d, fixed\n",

						dev->name, frag,

						skb_shinfo(skb)->nr_frags);

				goto linear;

			}

		}



		/* first frag which is skb header */

		pkt_info.byte_cnt = skb_headlen(skb);

		pkt_info.buf_ptr = dma_map_single(NULL, skb->data,
@@ -1288,6 +1294,8 @@ static int mv643xx_eth_start_xmit(struct sk_buff *skb, struct net_device *dev) 
		}

	}

#else

	spin_lock_irqsave(&mp->lock, flags);



	pkt_info.cmd_sts = ETH_TX_ENABLE_INTERRUPT | ETH_TX_FIRST_DESC |

							ETH_TX_LAST_DESC;

	pkt_info.l4i_chk = 0;