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SubjectRe: [PATCH net-next v2] wan: dscc4: add checks for dma mapping errors
Alexey Khoroshilov <khoroshilov@ispras.ru> :
[...]
> diff --git a/drivers/net/wan/dscc4.c b/drivers/net/wan/dscc4.c
> index 799830f..6a9ffac 100644
> --- a/drivers/net/wan/dscc4.c
> +++ b/drivers/net/wan/dscc4.c
> @@ -518,23 +518,31 @@ static void dscc4_release_ring(struct dscc4_dev_priv *dpriv)
> static inline int try_get_rx_skb(struct dscc4_dev_priv *dpriv,
> struct net_device *dev)
> {
> + struct pci_dev *pdev = dpriv->pci_priv->pdev;
> unsigned int dirty = dpriv->rx_dirty%RX_RING_SIZE;
> struct RxFD *rx_fd = dpriv->rx_fd + dirty;
> const int len = RX_MAX(HDLC_MAX_MRU);

For the edification of the masses, you may follow a strict inverted
xmas tree style (aka longer lines first as long as it does not bug).

[...]
> @@ -1147,14 +1155,22 @@ static netdev_tx_t dscc4_start_xmit(struct sk_buff *skb,
> struct dscc4_dev_priv *dpriv = dscc4_priv(dev);
> struct dscc4_pci_priv *ppriv = dpriv->pci_priv;
> struct TxFD *tx_fd;
> + dma_addr_t addr;
> int next;
>
> + addr = pci_map_single(ppriv->pdev, skb->data, skb->len,
> + PCI_DMA_TODEVICE);

Use a local struct pci_dev *pdev and it fits on a single line.

At some point it will probably be converted to plain dma api and use a 'd' dev.

[...]
> @@ -1887,16 +1903,22 @@ static struct sk_buff *dscc4_init_dummy_skb(struct dscc4_dev_priv *dpriv)
>
> skb = dev_alloc_skb(DUMMY_SKB_SIZE);
> if (skb) {
> + struct pci_dev *pdev = dpriv->pci_priv->pdev;
> int last = dpriv->tx_dirty%TX_RING_SIZE;
> struct TxFD *tx_fd = dpriv->tx_fd + last;
> + dma_addr_t addr;
>
> skb->len = DUMMY_SKB_SIZE;
> skb_copy_to_linear_data(skb, version,
> strlen(version) % DUMMY_SKB_SIZE);
> tx_fd->state = FrameEnd | TO_STATE_TX(DUMMY_SKB_SIZE);
> - tx_fd->data = cpu_to_le32(pci_map_single(dpriv->pci_priv->pdev,
> - skb->data, DUMMY_SKB_SIZE,
> - PCI_DMA_TODEVICE));
> + addr = pci_map_single(pdev, skb->data, DUMMY_SKB_SIZE,
> + PCI_DMA_TODEVICE);
> + if (pci_dma_mapping_error(pdev, addr)) {
> + dev_kfree_skb_any(skb);
> + return NULL;
> + }
> + tx_fd->data = cpu_to_le32(addr);
> dpriv->tx_skbuff[last] = skb;
> }
> return skb;

It isn't technically wrong but please don't update tx_fd before the mapping
succeeds. It will look marginally better.

Thanks.

--
Ueimor

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