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Message-ID: <ca0148c30805300552u7eb5da43tfc75127a2e819d1@mail.gmail.com>
Date: Fri, 30 May 2008 15:52:59 +0300
From: "Matti Linnanvuori" <mattilinn@...il.com>
To: "Krzysztof Halasa" <khc@...waw.pl>
Cc: jgarzik@...ox.com, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1.2.26] wan: new driver retina
2008/5/28 Krzysztof Halasa <khc@...waw.pl>:
> "Matti Linnanvuori" <mattilinn@...il.com> writes:
>
>> +/* net device related stuff: */
>> +#define FEPCI_NETDEV_IOCTL_STREAM_BUFSIZE 0x89F1
>> +#define FEPCI_NETDEV_IOCTL_STREAM_UNITSIZE 0x89F2
>> +#define FEPCI_NETDEV_IOCTL_STREAM_OPEN 0x89F3
>> +#define FEPCI_NETDEV_IOCTL_STREAM_START 0x89F4
>> +#define FEPCI_NETDEV_IOCTL_STREAM_CLOSE 0x89F6
>
> * THESE IOCTLS ARE _DEPRECATED_ AND WILL DISAPPEAR IN 2.5.X -DaveM
> */
>
> #define SIOCDEVPRIVATE 0x89F0 /* to 89FF */
>
> They haven't disappered yet but I'd rather use something else.
> Personally, sysfs stuff, unless you need to do it frequently/fast.
I would not like to change a legacy driver much.
>> +#define MAX_DEVICES 32u
>
> Why such artificial limit?
I have removed that.
>> +/* need to update MODULE_PARM also */
>> +#define MAX_INTERFACES (CHANNELS * MAX_DEVICES)
>
> Doesn't seem to be used anywhere.
I have removed that.
>> +#include <asm/pgtable.h>
>
> I'm not sure SetPageReserved() etc. belong to drivers.
I have removed that.
>> +module_param(retina_noarp_with_ptp, bool, S_IRUGO);
>> +MODULE_PARM_DESC(retina_noarp_with_ptp,
>> + "0 to disable NOARP, 1 to enable NOARP");
>
> Why not use a dynamic setting? ip link set XXX arp on|off?
I have removed that parameter.
>> + /* Process ID of the current mailbox user (for whom it is reserved) */
>> + unsigned int ioctl_saved_pid;
>
> Is this PID checking needed at all? It sure creates many problems,
> such as process' death and number wrapping.
I have replaced that with a mutex.
>> +/* global variables (common to whole driver, all the cards): */
>> +static int major; /* char device major number */
>> +static struct fepci_card_private card_privates[MAX_DEVICES];
>
> Why not dynamic?
I have made it dynamic.
>> +static int fepci_char_open(struct inode *inode, struct file *filp)
>> +{
>> + unsigned int minor = MINOR(inode->i_rdev);
>> + if (unlikely(minor >= find_cnt || card_privates[minor].pci_dev == NULL))
>> + return -ENXIO;
>> + filp->f_op = &fepci_char_fops;
>> + if (unlikely(!try_module_get(THIS_MODULE)))
>> + return -EBUSY;
>
> That won't work race-free, use owner field.
You mean the f_op assignment? I have removed that.
>> + if (offset == STREAM_BUFFER_POINTER_AREA) {
>> + virtual_address = stream_pointers;
>> + if (virtual_address == 0) {
>> + printk(KERN_WARNING "%s: mmap: internal error.\n",
>> + fepci_name);
>> + return -ENOMEM;
>> + }
>
> Why not just BUG_ON(!virtual_address)?
I just removed that because it seemed impossible.
>> + switch (get_semafore(real_mailbox)) {
>> + case 0x40:
>> + case 0x20:
>> + case 0x21:
>> + /* copy the mailbox */
>> + retval = fepci_copy_from_user(ioaddr +
>> + FEPCI_MAILBOX_OFFSETT + 4,
>> + arg + 2, _IOC_SIZE(cmd) - 2, 1);
>> + /* semafore -> 10 */
>> + set_semafore(real_mailbox, 0x10);
>> + mod_timer(&card_privates[minor].mailbox_timer,
>> + jiffies + 20 * HZ);
>> + break;
>> + case 0x10:
>> + case 0x11:
>> + case 0x80:
>
> Some comments about real_mailbox values maybe?
I have replaced them with enumerated values.
>> +static ssize_t fepci_char_read(struct file *filp, char __user *buf,
>> + size_t count, loff_t *f_pos)
>> +{
>> + if (count > 1)
>> + count = 1;
>> + if (unlikely(copy_to_user(buf, "\n", count)))
>> + return -EFAULT;
>> + return count;
>> +}
>
> So why exactly is the above useful?
I have removed that.
>> +static int fepci_stream_open_down(struct net_device *dev,
>> + struct fepci_ch_private *fp)
>> +{
>> + unsigned tx_pages, rx_pages, tx_order, rx_order;
>> + unsigned page_number;
>> + unsigned int i;
>> +
>> + if (unlikely(fp->in_eth_mode)) {
>> + dev_warn(&dev->dev,
>> + "Interface is in Ethernet mode, "
>> + "cannot open stream interface\n");
>> + return -EBUSY;
>> + }
>
> Some locking maybe? That seems like a great recipe for races.
> I'd check the recent discussions about the big kernel lock too.
Private net device ioctls are locked with rtnl_lock, so I see no race there.
>> + for (page_number = 0; page_number < rx_pages; page_number++)
>> + /* make pages reserved to allow remappping pages
>> + with io_remap_pfn_range */
>> + SetPageReserved(virt_to_page
>> + ((unsigned long)fp->rx_buffer +
>> + (page_number << PAGE_SHIFT)));
>> + for (page_number = 0; page_number < tx_pages; page_number++)
>> + /* make pages reserved to allow remappping pages
>> + with io_remap_pfn_range */
>> + SetPageReserved(virt_to_page
>> + ((unsigned long)fp->tx_buffer +
>> + (page_number << PAGE_SHIFT)));
>
> Looks dangerous.
I have removed that.
>> +static inline void fepci_stream_stop(struct net_device *dev,
>> + struct fepci_ch_private *fp)
>> +{
>> + uint8_t __iomem *ioaddr = (uint8_t __iomem *)dev->base_addr;
>> + fp->stream_on = 0;
>> + /* Stop Rx and Tx channels. */
>> + writel(0x0, ioaddr + fp->reg_rxctrl);
>> + writel(0x0, ioaddr + fp->reg_txctrl);
>> +
>> + /* Disable interrupts by clearing the interrupt mask. */
>> + set_int_mask(fp->channel_number, 0x0, fp->this_card_priv);
>> +
>> + /* unregister irq */
>> + free_irq(dev->irq, dev);
>> +
>> + {
>> + unsigned i = min(RX_RING_SIZE, TX_RING_SIZE) - 1;
>> + do {
>> + if (likely(!pci_dma_mapping_error(
>> + pci_unmap_addr(fp->rx + i, address))))
>> + pci_unmap_single(fp->this_card_priv->
>> + pci_dev,
>> + pci_unmap_addr(fp->rx + i,
>> + address),
>> + fp->unit_sz,
>> + PCI_DMA_FROMDEVICE);
>> + if (likely(!pci_dma_mapping_error(
>> + pci_unmap_addr(fp->tx + i, address))))
>> + pci_unmap_single(fp->this_card_priv->
>> + pci_dev,
>> + pci_unmap_addr(fp->tx + i,
>> + address),
>> + fp->unit_sz, PCI_DMA_TODEVICE);
>> + } while (i--);
>> + }
>> +}
>
> If you move this "unsigned i" (or better unsigned v or something as
> "i" is usually used for pure ints) to the start of this function,
> the code will look much better.
I have removed the block.
>> +static int fepci_rebuild_header(struct sk_buff *skb)
>> +{
>> + return 0;
>> +}
>
> Unneeded?
I have removed that.
>> +static int __devinit fepci_init_one(struct pci_dev *pdev,
>> + const struct pci_device_id *ent)
>> +{
>
> + if (PCI_FUNC(pdev->devfn) != 0)
>> + return -ENXIO;
>
> Don't you plan multi-function cards? :-)
No, I don't. I got some erroneous multi-function values once.
>> + /* HW_ADDR is got using the mailbox: */
>> + {
>> + struct fepci_real_mailbox __iomem *real_mailbox =
>> + (struct fepci_real_mailbox __iomem *)
>> + (ioaddr + FEPCI_MAILBOX_OFFSETT);
>
> Same comment about moving variable to the start (of the parent block
> maybe). If you want it to be a separate function then do that.
I changed that, too.
>> +static int fepci_open(struct net_device *dev)
>> +{
>> + struct fepci_ch_private *fp = netdev_priv(dev);
>> + if (unlikely(fp->in_stream_mode))
>> + fepci_stream_close_down(dev, fp);
>
> Wouldn't it be better to return -EBUSY instead?
I think it is better to allow a user more freedom.
>> +static int fepci_start_xmit(struct sk_buff *skb, struct net_device *dev)
>> +{
>> + struct fepci_ch_private *fp;
>> + unsigned cur_tx;
>> + unsigned next;
>> + unsigned tx_length;
>> + dma_addr_t bus_address;
>> +
>> + if (unlikely(skb_padto(skb, ETH_ZLEN)))
>> + return NETDEV_TX_OK;
>
> Statistics maybe?
I have added statistics increase.
>> +static inline void fepci_rx(struct fepci_ch_private *fp, struct
>> net_device *dev)
>> +{
>> + if (!(desc_b & transfer_not_done)) { /* transfer done */
>> + fp->cur_rx = (i + 1) & (RX_RING_SIZE - 1);
>> + if (unlikely(desc_b & (fifo_error | size_error |
>> + crc_error | octet_error |
>> + line_error))) {
>> + if (desc_b & fifo_error)
>> + fp->stats.rx_frame_errors++;
>> + else if (desc_b & size_error)
>> + fp->stats.rx_over_errors++;
>> + else if (desc_b & crc_error)
>> + fp->stats.rx_crc_errors++;
>> +ENABLE_TRANSFER: writel(enable_transfer, &rx_desc->desc_b);
>> + fp->stats.rx_errors++;
>> + continue;
>> + } else {
>
> You don't need "else" due to "continue", right? More space for you.
Done.
>> +static struct net_device_stats *fepci_get_stats(struct net_device *dev)
>> +{
>> + struct fepci_ch_private *fp = netdev_priv(dev);
>> + return &fp->stats;
>> +}
>
> If you use the built-in net_device_stats you don't need the function.
I have moved to built-in.
>> +static void set_rx_mode(struct net_device *dev)
>> +{
>> + dev_dbg(&dev->dev, "set_rx_mode\n");
>> +}
>
> Seems unused.
Removed.
A new patch is at http://groups.google.com/group/pcidriver
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