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net: fec: make rx skb handling more robust

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Allocate, and then map the receive skb before writing any data to the
ring descriptor or storing the skb.  When freeing the receive ring
entries, unmap and free the skb, and then clear the stored skb pointer.

This means we have ring data and skb pointer in one of two states:
either both fully setup, or nothing setup.

This simplifies the cleanup, as we can use just the skb pointer to
indicate whether the descriptor is setup, and thus avoids potentially
calling dma_unmap_single() on a DMA error value.

Acked-by: Fugang Duan <B38611@freescale.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Russell King 2014-07-08 00:23:14 +01:00 committed by David S. Miller
parent 5d165c5543
commit 730ee3602f
1 changed files with 11 additions and 6 deletions
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17
drivers/net/ethernet/freescale/fec_main.c
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@ -2066,12 +2066,12 @@ static void fec_enet_free_buffers(struct net_device *ndev)
bdp = fep->rx_bd_base;
for (i = 0; i < fep->rx_ring_size; i++) {
skb = fep->rx_skbuff[i];
if (bdp->cbd_bufaddr)
fep->rx_skbuff[i] = NULL;
if (skb) {
dma_unmap_single(&fep->pdev->dev, bdp->cbd_bufaddr,
FEC_ENET_RX_FRSIZE, DMA_FROM_DEVICE);
if (skb)
dev_kfree_skb(skb);
}
bdp = fec_enet_get_nextdesc(bdp, fep);
}
@ -2089,21 +2089,26 @@ static int fec_enet_alloc_buffers(struct net_device *ndev)
bdp = fep->rx_bd_base;
for (i = 0; i < fep->rx_ring_size; i++) {
dma_addr_t addr;
skb = netdev_alloc_skb(ndev, FEC_ENET_RX_FRSIZE);
if (!skb) {
fec_enet_free_buffers(ndev);
return -ENOMEM;
}
fep->rx_skbuff[i] = skb;
bdp->cbd_bufaddr = dma_map_single(&fep->pdev->dev, skb->data,
addr = dma_map_single(&fep->pdev->dev, skb->data,
FEC_ENET_RX_FRSIZE, DMA_FROM_DEVICE);
if (dma_mapping_error(&fep->pdev->dev, bdp->cbd_bufaddr)) {
if (dma_mapping_error(&fep->pdev->dev, addr)) {
dev_kfree_skb(skb);
fec_enet_free_buffers(ndev);
if (net_ratelimit())
netdev_err(ndev, "Rx DMA memory map failed\n");
return -ENOMEM;
}
fep->rx_skbuff[i] = skb;
bdp->cbd_bufaddr = addr;
bdp->cbd_sc = BD_ENET_RX_EMPTY;
if (fep->bufdesc_ex) {