From b748d9e3b80dc7e6ce6bf7399f57964b99a4104c Mon Sep 17 00:00:00 2001 From: Neil Horman Date: Fri, 20 Apr 2007 09:54:58 -0400 Subject: sis900: Allocate rx replacement buffer before rx operation The sis900 driver appears to have a bug in which the receive routine passes the skbuff holding the received frame to the network stack before refilling the buffer in the rx ring. If a new skbuff cannot be allocated, the driver simply leaves a hole in the rx ring, which causes the driver to stop receiving frames and become non-recoverable without an rmmod/insmod according to reporters. This patch reverses that order, attempting to allocate a replacement buffer first, and receiving the new frame only if one can be allocated. If no skbuff can be allocated, the current skbuf in the rx ring is recycled, dropping the current frame, but keeping the NIC operational. Signed-off-by: Neil Horman Signed-off-by: Jeff Garzik --- drivers/net/sis900.c | 44 ++++++++++++++++++++------------------------ 1 file changed, 20 insertions(+), 24 deletions(-) diff --git a/drivers/net/sis900.c b/drivers/net/sis900.c index b3750f284279..b2a3b19d773a 100644 --- a/drivers/net/sis900.c +++ b/drivers/net/sis900.c @@ -1755,6 +1755,24 @@ static int sis900_rx(struct net_device *net_dev) } else { struct sk_buff * skb; + pci_unmap_single(sis_priv->pci_dev, + sis_priv->rx_ring[entry].bufptr, RX_BUF_SIZE, + PCI_DMA_FROMDEVICE); + + /* refill the Rx buffer, what if there is not enought + * memory for new socket buffer ?? */ + if ((skb = dev_alloc_skb(RX_BUF_SIZE)) == NULL) { + /* + * Not enough memory to refill the buffer + * so we need to recycle the old one so + * as to avoid creating a memory hole + * in the rx ring + */ + skb = sis_priv->rx_skbuff[entry]; + sis_priv->stats.rx_dropped++; + goto refill_rx_ring; + } + /* This situation should never happen, but due to some unknow bugs, it is possible that we are working on NULL sk_buff :-( */ @@ -1768,9 +1786,6 @@ static int sis900_rx(struct net_device *net_dev) break; } - pci_unmap_single(sis_priv->pci_dev, - sis_priv->rx_ring[entry].bufptr, RX_BUF_SIZE, - PCI_DMA_FROMDEVICE); /* give the socket buffer to upper layers */ skb = sis_priv->rx_skbuff[entry]; skb_put(skb, rx_size); @@ -1783,33 +1798,14 @@ static int sis900_rx(struct net_device *net_dev) net_dev->last_rx = jiffies; sis_priv->stats.rx_bytes += rx_size; sis_priv->stats.rx_packets++; - - /* refill the Rx buffer, what if there is not enought - * memory for new socket buffer ?? */ - if ((skb = dev_alloc_skb(RX_BUF_SIZE)) == NULL) { - /* not enough memory for skbuff, this makes a - * "hole" on the buffer ring, it is not clear - * how the hardware will react to this kind - * of degenerated buffer */ - if (netif_msg_rx_status(sis_priv)) - printk(KERN_INFO "%s: Memory squeeze," - "deferring packet.\n", - net_dev->name); - sis_priv->rx_skbuff[entry] = NULL; - /* reset buffer descriptor state */ - sis_priv->rx_ring[entry].cmdsts = 0; - sis_priv->rx_ring[entry].bufptr = 0; - sis_priv->stats.rx_dropped++; - sis_priv->cur_rx++; - break; - } + sis_priv->dirty_rx++; +refill_rx_ring: skb->dev = net_dev; sis_priv->rx_skbuff[entry] = skb; sis_priv->rx_ring[entry].cmdsts = RX_BUF_SIZE; sis_priv->rx_ring[entry].bufptr = pci_map_single(sis_priv->pci_dev, skb->data, RX_BUF_SIZE, PCI_DMA_FROMDEVICE); - sis_priv->dirty_rx++; } sis_priv->cur_rx++; entry = sis_priv->cur_rx % NUM_RX_DESC; -- cgit v1.2.3-59-g8ed1b