Commit 2d38caba authored by Lennert Buytenhek's avatar Lennert Buytenhek Committed by Jeff Garzik
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[PATCH] ep93xx_eth: fix RX/TXstatus ring full handling 



Ray Lehtiniemi reported that an incoming UDP packet flood can lock up
the ep93xx ethernet driver.  Herbert Valerio Riedel noted that due to
the way ep93xx_eth manages the RX/TXstatus rings, it cannot distinguish
a full ring from an empty one, and correctly suggested that this was
likely to be causing this lockup to occur.

Instead of looking at the hardware's RX/TXstatus ring write pointers
to determine when to stop reading from those rings, we should just check
every individual RX/TXstatus descriptor's valid bit instead, since there
is no other way to distinguish an empty ring from a full ring, and if
there is a descriptor waiting, we take the hit of reading the descriptor
from memory anyway.

Signed-off-by: default avatarLennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: default avatarJeff Garzik <jeff@garzik.org>
parent d5b9b787

drivers/net/arm/ep93xx_eth.c

+9 −26
Original line number Diff line number Diff line
@@ -193,12 +193,9 @@ static struct net_device_stats *ep93xx_get_stats(struct net_device *dev) 
static int ep93xx_rx(struct net_device *dev, int *budget)

{

	struct ep93xx_priv *ep = netdev_priv(dev);

	int tail_offset;

	int rx_done;

	int processed;



	tail_offset = rdl(ep, REG_RXSTSQCURADD) - ep->descs_dma_addr;



	rx_done = 0;

	processed = 0;

	while (*budget > 0) {
@@ -211,28 +208,23 @@ static int ep93xx_rx(struct net_device *dev, int *budget) 


		entry = ep->rx_pointer;

		rstat = ep->descs->rstat + entry;

		if ((void *)rstat - (void *)ep->descs == tail_offset) {



		rstat0 = rstat->rstat0;

		rstat1 = rstat->rstat1;

		if (!(rstat0 & RSTAT0_RFP) || !(rstat1 & RSTAT1_RFP)) {

			rx_done = 1;

			break;

		}



		rstat0 = rstat->rstat0;

		rstat1 = rstat->rstat1;

		rstat->rstat0 = 0;

		rstat->rstat1 = 0;



		if (!(rstat0 & RSTAT0_RFP))

			printk(KERN_CRIT "ep93xx_rx: buffer not done "

					 " %.8x %.8x\n", rstat0, rstat1);

		if (!(rstat0 & RSTAT0_EOF))

			printk(KERN_CRIT "ep93xx_rx: not end-of-frame "

					 " %.8x %.8x\n", rstat0, rstat1);

		if (!(rstat0 & RSTAT0_EOB))

			printk(KERN_CRIT "ep93xx_rx: not end-of-buffer "

					 " %.8x %.8x\n", rstat0, rstat1);

		if (!(rstat1 & RSTAT1_RFP))

			printk(KERN_CRIT "ep93xx_rx: buffer1 not done "

					 " %.8x %.8x\n", rstat0, rstat1);

		if ((rstat1 & RSTAT1_BUFFER_INDEX) >> 16 != entry)

			printk(KERN_CRIT "ep93xx_rx: entry mismatch "

					 " %.8x %.8x\n", rstat0, rstat1);
@@ -301,13 +293,8 @@ err: 


static int ep93xx_have_more_rx(struct ep93xx_priv *ep)

{

	struct ep93xx_rstat *rstat;

	int tail_offset;



	rstat = ep->descs->rstat + ep->rx_pointer;

	tail_offset = rdl(ep, REG_RXSTSQCURADD) - ep->descs_dma_addr;



	return !((void *)rstat - (void *)ep->descs == tail_offset);

	struct ep93xx_rstat *rstat = ep->descs->rstat + ep->rx_pointer;

	return !!((rstat->rstat0 & RSTAT0_RFP) && (rstat->rstat1 & RSTAT1_RFP));

}



static int ep93xx_poll(struct net_device *dev, int *budget)
@@ -379,10 +366,8 @@ static int ep93xx_xmit(struct sk_buff *skb, struct net_device *dev) 
static void ep93xx_tx_complete(struct net_device *dev)

{

	struct ep93xx_priv *ep = netdev_priv(dev);

	int tail_offset;

	int wake;



	tail_offset = rdl(ep, REG_TXSTSQCURADD) - ep->descs_dma_addr;

	wake = 0;



	spin_lock(&ep->tx_pending_lock);
@@ -393,15 +378,13 @@ static void ep93xx_tx_complete(struct net_device *dev) 


		entry = ep->tx_clean_pointer;

		tstat = ep->descs->tstat + entry;

		if ((void *)tstat - (void *)ep->descs == tail_offset)

			break;



		tstat0 = tstat->tstat0;

		if (!(tstat0 & TSTAT0_TXFP))

			break;



		tstat->tstat0 = 0;



		if (!(tstat0 & TSTAT0_TXFP))

			printk(KERN_CRIT "ep93xx_tx_complete: buffer not done "

					 " %.8x\n", tstat0);

		if (tstat0 & TSTAT0_FA)

			printk(KERN_CRIT "ep93xx_tx_complete: frame aborted "

					 " %.8x\n", tstat0);

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