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Commit 815b97c6 authored by Andy Fleming's avatar Andy Fleming Committed by Jeff Garzik
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gianfar: Fix skb allocation strategy 



gianfar was unable to handle failed skb allocation for rx buffers, so
we were spinning until it succeeded.  Actually, it was worse--we were
spinning for a long time, and then silently failing.  Instead, we take
Stephen Hemminger's suggestion to try the allocation earlier, and drop the
packet if it failed.

We also make a couple of tweaks to how buffer descriptors are set up.

Signed-off-by: default avatarAndy Fleming <afleming@freescale.com>
Signed-off-by: default avatarJeff Garzik <jgarzik@redhat.com>
parent 8d74849b

drivers/net/gianfar.c

+65 −35
Original line number Diff line number Diff line
@@ -98,7 +98,6 @@ 
#include "gianfar_mii.h"



#define TX_TIMEOUT      (1*HZ)

#define SKB_ALLOC_TIMEOUT 1000000

#undef BRIEF_GFAR_ERRORS

#undef VERBOSE_GFAR_ERRORS
@@ -115,7 +114,9 @@ static int gfar_enet_open(struct net_device *dev); 
static int gfar_start_xmit(struct sk_buff *skb, struct net_device *dev);

static void gfar_timeout(struct net_device *dev);

static int gfar_close(struct net_device *dev);

struct sk_buff *gfar_new_skb(struct net_device *dev, struct rxbd8 *bdp);

struct sk_buff *gfar_new_skb(struct net_device *dev);

static void gfar_new_rxbdp(struct net_device *dev, struct rxbd8 *bdp,

		struct sk_buff *skb);

static int gfar_set_mac_address(struct net_device *dev);

static int gfar_change_mtu(struct net_device *dev, int new_mtu);

static irqreturn_t gfar_error(int irq, void *dev_id);
@@ -783,14 +784,21 @@ int startup_gfar(struct net_device *dev) 


	rxbdp = priv->rx_bd_base;

	for (i = 0; i < priv->rx_ring_size; i++) {

		struct sk_buff *skb = NULL;

		struct sk_buff *skb;



		rxbdp->status = 0;

		skb = gfar_new_skb(dev);



		skb = gfar_new_skb(dev, rxbdp);

		if (!skb) {

			printk(KERN_ERR "%s: Can't allocate RX buffers\n",

					dev->name);



			goto err_rxalloc_fail;

		}



		priv->rx_skbuff[i] = skb;



		gfar_new_rxbdp(dev, rxbdp, skb);



		rxbdp++;

	}
@@ -916,6 +924,7 @@ rx_irq_fail: 
tx_irq_fail:

	free_irq(priv->interruptError, dev);

err_irq_fail:

err_rxalloc_fail:	

rx_skb_fail:

	free_skb_resources(priv);

tx_skb_fail:
@@ -1328,18 +1337,37 @@ static irqreturn_t gfar_transmit(int irq, void *dev_id) 
	return IRQ_HANDLED;

}



struct sk_buff * gfar_new_skb(struct net_device *dev, struct rxbd8 *bdp)

static void gfar_new_rxbdp(struct net_device *dev, struct rxbd8 *bdp,

		struct sk_buff *skb)

{

	struct gfar_private *priv = netdev_priv(dev);

	u32 * status_len = (u32 *)bdp;

	u16 flags;



	bdp->bufPtr = dma_map_single(&dev->dev, skb->data,

			priv->rx_buffer_size, DMA_FROM_DEVICE);



	flags = RXBD_EMPTY | RXBD_INTERRUPT;



	if (bdp == priv->rx_bd_base + priv->rx_ring_size - 1)

		flags |= RXBD_WRAP;



	eieio();



	*status_len = (u32)flags << 16;

}





struct sk_buff * gfar_new_skb(struct net_device *dev)

{

	unsigned int alignamount;

	struct gfar_private *priv = netdev_priv(dev);

	struct sk_buff *skb = NULL;

	unsigned int timeout = SKB_ALLOC_TIMEOUT;



	/* We have to allocate the skb, so keep trying till we succeed */

	while ((!skb) && timeout--)

		skb = dev_alloc_skb(priv->rx_buffer_size + RXBUF_ALIGNMENT);

	skb = netdev_alloc_skb(dev, priv->rx_buffer_size + RXBUF_ALIGNMENT);



	if (NULL == skb)

	if (!skb)

		return NULL;



	alignamount = RXBUF_ALIGNMENT -
@@ -1350,15 +1378,6 @@ struct sk_buff * gfar_new_skb(struct net_device *dev, struct rxbd8 *bdp) 
	 */

	skb_reserve(skb, alignamount);



	bdp->bufPtr = dma_map_single(&dev->dev, skb->data,

			priv->rx_buffer_size, DMA_FROM_DEVICE);



	bdp->length = 0;



	/* Mark the buffer empty */

	eieio();

	bdp->status |= (RXBD_EMPTY | RXBD_INTERRUPT);



	return skb;

}
@@ -1544,10 +1563,31 @@ int gfar_clean_rx_ring(struct net_device *dev, int rx_work_limit) 
	bdp = priv->cur_rx;



	while (!((bdp->status & RXBD_EMPTY) || (--rx_work_limit < 0))) {

		struct sk_buff *newskb;

		rmb();



		/* Add another skb for the future */

		newskb = gfar_new_skb(dev);



		skb = priv->rx_skbuff[priv->skb_currx];



		if ((bdp->status & RXBD_LAST) && !(bdp->status & RXBD_ERR)) {

		/* We drop the frame if we failed to allocate a new buffer */

		if (unlikely(!newskb || !(bdp->status & RXBD_LAST) ||

				 bdp->status & RXBD_ERR)) {

			count_errors(bdp->status, dev);



			if (unlikely(!newskb))

				newskb = skb;



			if (skb) {

				dma_unmap_single(&priv->dev->dev,

						bdp->bufPtr,

						priv->rx_buffer_size,

						DMA_FROM_DEVICE);



				dev_kfree_skb_any(skb);

			}

		} else {

			/* Increment the number of packets */

			dev->stats.rx_packets++;

			howmany++;
@@ -1558,23 +1598,14 @@ int gfar_clean_rx_ring(struct net_device *dev, int rx_work_limit) 
			gfar_process_frame(dev, skb, pkt_len);



			dev->stats.rx_bytes += pkt_len;

		} else {

			count_errors(bdp->status, dev);



			if (skb)

				dev_kfree_skb_any(skb);



			priv->rx_skbuff[priv->skb_currx] = NULL;

		}



		dev->last_rx = jiffies;



		/* Clear the status flags for this buffer */

		bdp->status &= ~RXBD_STATS;

		priv->rx_skbuff[priv->skb_currx] = newskb;



		/* Add another skb for the future */

		skb = gfar_new_skb(dev, bdp);

		priv->rx_skbuff[priv->skb_currx] = skb;

		/* Setup the new bdp */

		gfar_new_rxbdp(dev, bdp, newskb);



		/* Update to the next pointer */

		if (bdp->status & RXBD_WRAP)
@@ -1584,9 +1615,8 @@ int gfar_clean_rx_ring(struct net_device *dev, int rx_work_limit) 


		/* update to point at the next skb */

		priv->skb_currx =

		    (priv->skb_currx +

		     1) & RX_RING_MOD_MASK(priv->rx_ring_size);



		    (priv->skb_currx + 1) &

		    RX_RING_MOD_MASK(priv->rx_ring_size);

	}



	/* Update the current rxbd pointer to be the next one */