Date:	Tue, 20 Mar 2012 09:40:00 +0100
From:	Andreas Fenkart <afenkart@...il.com>
To:	David Miller <davem@...emloft.net>
Cc:	netdev@...r.kernel.org
Subject: Re: [PATCH] ARC VMAC driver.

David,

Am 5. März 2012 21:30 schrieb David Miller <davem@...emloft.net>:
> From: Andreas Fenkart <afenkart@...il.com>
> Date: Mon,  5 Mar 2012 10:59:45 +0100
>
>> +     unsigned mac_lo, mac_hi;
>
> Please never say just "unsigned" but instead use "unsigned int"
> But in this case you're dealing with a fixed sized value so
> "u32" is most appropriate.
>
>> +     unsigned mac_lo, mac_hi;
>
> Same here.
>
>> +static void vmac_mdio_xmit(struct vmac_priv *ap, unsigned val)
>
> Again.  So please fix this up in the entire driver.
>
>> +     int report_change = 0;
>
> Please use 'bool' as the type and 'true' and 'false' as the values.
>
>> +     ap->mii_bus = mdiobus_alloc();
>> +     if (ap->mii_bus == NULL)
>> +             return -ENOMEM;
>
> Use "if (!ap->mii_bus)" for null pointer checks.
>
>> +     ap->mii_bus->irq = kmalloc(sizeof(int) * PHY_MAX_ADDR, GFP_KERNEL);
>> +     if (!ap->mii_bus->irq)
>
> Which inconsistently you do correctly here.
>
>> +     struct vmac_priv *ap = netdev_priv(dev);
>> +     dev_dbg(&ap->pdev->dev, "rx error counter overrun. status = 0x%x\n",
>> +                     status);
>
> Please add an empty line between the function variable declarations and
> the first actual code statement.
>
>> +     if (!fifo_empty(&ap->rx_ring)) {
>> +             dev_err(&ap->pdev->dev, "failed to reclaim %d rx sk_buff\n",
>> +                             fifo_used(&ap->rx_ring));
>> +     }
>
> You don't need openning and closing braces for a single line basic
> block.  It just takes up an unnecessary extra line in the source.
>
>> +     /* locking: fct owns rx_ring tail to current DMA read position, alias
>> +      * 'received packets'. rx_refill owns area outside rx_ring, doesn't
>> +      * modify tail */
>
> Code comments:
>
>        /* Like
>         * this.
>         */
>
>         /* Or like this. */
>
>         /* But not
>          * like this. */
>
>
> There are other instances of this issue in the driver, please fix those
> too.
>
>> +     unsigned long tmp;
>
> This is a 32-bit value not a long which is a non-fixed-sized type
> and might be 64-bit.  You definitely want to use "u32" for these.
>
>> +static void vmac_toggle_rxint_unlocked(struct net_device *dev, int enable)
>
> Use 'bool' for all the places where you do this "enable" argument in
> functions.
>
>> +     if ((status & RXINT_MASK) && (vmac_readl(ap, ENABLE) && RXINT_MASK) &&
>
> All of these register bit tests are wrong, you're using "&&
> RXINT_MASK" instead of "& RXINT_MASK".
>
>> +     if ((status & TXINT_MASK) && (vmac_readl(ap, ENABLE) && TXINT_MASK)) {
>
> Same bug.
>
>> +static int vmac_tx_reclaim_unlocked(struct net_device *dev, int force)
>> +{
>> +     struct vmac_priv *ap = netdev_priv(dev);
>> +     int released = 0;
>
> Use 'bool' and true/false for 'force' and 'released'.
>
>> +             dev_kfree_skb_any(skb);
>
> You only need to use the significantly more expensive dev_kfree_skb_any() if this
> code can run in a hardware interrupt handler.
>
> This is a NAPI driver and therefore it should only do reclaim from
> NAPI poll and thus software interrupt context.  Therefore you can use
> dev_kfree_skb() which is 10 times faster than dev_kfree_skb_any()
> which results in a new software interrupt getting queued up.
>
>> +     if (unlikely(skb->len < ETH_ZLEN)) {
>> +             struct sk_buff *short_skb;
>> +             short_skb = netdev_alloc_skb(dev, ETH_ZLEN);
>> +             if (!short_skb)
>> +                     return NETDEV_TX_LOCKED;
>> +
>> +             memset(short_skb->data, 0, ETH_ZLEN);
>> +             memcpy(skb_put(short_skb, ETH_ZLEN), skb->data, skb->len);
>> +             dev_kfree_skb(skb);
>> +             skb = short_skb;
>> +     }
>
> Don't reinvent the wheel, use skb_pad() or similar, which is much more efficient
> than this open-coded version.
>
>> +     desc->data = dma_map_single(&ap->pdev->dev, skb->data, skb->len,
>> +                     DMA_TO_DEVICE);
>
> Align the argument up to the openning parenthesis on the previous line:
>
>        desc->data = dma_map_single(&ap->pdev->dev, skb->data, skb->len,
>                                    DMA_TO_DEVICE);
>
>> +     ap->rxbd = dma_alloc_coherent(&ap->pdev->dev, size,
>> +                     &ap->rxbd_dma,
>> +                     GFP_KERNEL);
>
> Same problem.
>
>> +     if (ap->rxbd == NULL)
>
> Test with "if (!ptr)" not "if (ptr == NULL)"
>
>> +     ap->txbd = dma_alloc_coherent(&ap->pdev->dev, size,
>> +                     &ap->txbd_dma,
>> +                     GFP_KERNEL);
>
> Argument alignment.
>
>> +     dma_free_coherent(&ap->pdev->dev, sizeof(*ap->txbd) * ap->tx_ring.size,
>> +                     ap->txbd, ap->txbd_dma);
>  ...
>> +     dma_free_coherent(&ap->pdev->dev, sizeof(*ap->rxbd) * ap->rx_ring.size,
>> +                     ap->rxbd, ap->rxbd_dma);
>
> Again and again.
>
>> +     dma_free_coherent(&ap->pdev->dev, sizeof(ap->txbd) * ap->tx_ring.size,
>> +                     ap->txbd, ap->txbd_dma);
>> +     dma_free_coherent(&ap->pdev->dev, sizeof(ap->rxbd) * ap->rx_ring.size,
>> +                     ap->rxbd, ap->rxbd_dma);
>
> More of the same.
>
>> +     if (ap == NULL)
>
> Test "if (!ap)" instad.
>
>> +             dev_err(&ap->pdev->dev, "Unable to request IRQ %d (error %d)\n",
>> +                             dev->irq, err);
>
> Argument alignment.
>
>> +     temp |= ERR_MASK | TXCH_MASK | MSER_MASK | RXCR_MASK | RXFR_MASK | \
>> +                                     RXFL_MASK;
>
> There is no reason to escape the newline with a "\" here, get rid of that.
>
>> +     dev_info(&ap->pdev->dev, "PHY driver [%s] (mii_bus:phy_addr=%s, irq=%d)\n",
>> +            phydev->drv->name, dev_name(&phydev->dev), phydev->irq);
>
> Argument alignment.
>
>> +     unsigned int temp;
>
> Use "u32" for the type.
>
>> +static void create_multicast_filter(struct net_device *dev,
>> +     int32_t *bitmask)
>
> Argument alignment.
>
>> +     int promisc, reg;
>
> Use 'bool' for 'promisc', use 'u32' for 'reg'.
>
>> +     int32_t bitmask[2];
>
> Don't use int32_t in the kernel, use 'u32' instead.
>
>> +     if (dma_get_mask(&pdev->dev) > DMA_BIT_MASK(32) ||
>> +                     pdev->dev.coherent_dma_mask > DMA_BIT_MASK(32)) {
>
> Align things properly:
>
>        if (dma_get_mask(&pdev->dev) > DMA_BIT_MASK(32) ||
>            pdev->dev.coherent_dma_mask > DMA_BIT_MASK(32)) {
>
>> +     dev->flags |= IFF_MULTICAST;
>
> Why in the world do you need to do this?  The ethernet generic setup takes
> care of this for you.
>
>> +     if (!is_valid_ether_addr(dev->dev_addr))
>> +             random_ether_addr(dev->dev_addr);
>
> Use dev_hw_addr_random() which will properly set the NET_ADDR_RANDOM attribute
> properly too.
>
>> +     dev_info(&pdev->dev, "ARC VMAC at 0x%pP irq %d %pM\n", &mem->start,
>> +         dev->irq, dev->dev_addr);
>
> Align the arguments properly.
>
>> +struct       vmac_priv {
>
> Get rid of that ugly tab, use a single space instead.
>
>> +static inline int fifo_empty(struct dma_fifo *f)
>
> Return 'bool'.
>
>> +static inline int fifo_full(struct dma_fifo *f)
>
> Return 'bool'.
>> +     pr_info("fifo: head %d, tail %d, size %d\n", fifo->head,
>> +                     fifo->tail,
>> +                     fifo->size);
>
> Align arguments properly.

Thanks. I fixed and I'll be sending out a rev 2 shortly.

Regards
Andi
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