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    SubjectRe: [PATCH] drivers/net/usb/asix: resync from vendor's copy
    On 11-11-09 12:31 PM, Ben Hutchings wrote:
    > On Wed, 2011-11-09 at 12:20 -0500, Mark Lord wrote:
    >> On 11-11-09 11:57 AM, Mark Lord wrote:
    >>> On 11-11-09 11:47 AM, Mark Lord wrote:
    >>> ..
    >>>> Note: I'm looking at smsc95xx.c and smsc75xx.c for examples,
    >>>> and they both have the same problem I'll have here:
    >>>>
    >>>> How to update the csum settings atomically.
    >>>> A spinlock is no good, because config register access is over USB.
    >>>
    >>> Nevermind.. a slight change in the logic and all is well again.
    >> ..
    >>
    >> Or even simpler (below). I don't think this method requires any
    >> extra locking, but I'm still open to persuasion. :)
    >
    > Looks reasonable, but...
    >
    >> static int ax88772b_set_features(struct net_device *netdev, u32 features)
    >> {
    >> struct usbnet *dev = netdev_priv(netdev);
    >> struct ax88772b_data *priv = (struct ax88772b_data *)dev->driver_priv;
    >> u16 tx_csum = 0, rx_csum = 0;
    >>
    >> priv->features = features & (NETIF_F_HW_CSUM | NETIF_F_RXCSUM);
    >
    > ...why do you need priv->features at all?


    There's code elsewhere that takes action under some conditions
    based on the current setting of the NETIF_F_RXCSUM flag.

    I don't claim to fully understand what's going on,
    but it doesn't care much about races on set/clear of the flag.

    Cheers


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