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Date: Tue, 22 Apr 2008 17:18:29 -0500
From: Andy Fleming <afleming@...escale.com>
To: jgarzik@...ox.com
Cc: shemminger@...tta.com, netdev@...r.kernel.org,
Andy Fleming <afleming@...escale.com>
Subject: [PATCH v2.6.26] 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: Andy Fleming <afleming@...escale.com>
---
drivers/net/gianfar.c | 100 ++++++++++++++++++++++++++++++++-----------------
1 files changed, 65 insertions(+), 35 deletions(-)
diff --git a/drivers/net/gianfar.c b/drivers/net/gianfar.c
index c8c3df7..015ce3e 100644
--- a/drivers/net/gianfar.c
+++ b/drivers/net/gianfar.c
@@ -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 */
--
1.5.4.GIT
--
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